THIS BOOK IS FROM
THE LIBRARY OF

Richard Haven Backus

?^^^^^^^^^^^^

1930

Gift of

Richard H. Backus

May, 1988

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ANIMAL COMMUNITIES IN
TEMPERATE AMERICA

THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS

THE BAKER & TAYLOR COMPANY
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THE GEOGRAPHIC SOCIETY OF CHICAGO

Bulletin No. 5

ANIMAL COMMUNITIES
IN TEMPERATE AMERICA

AS ILLUSTRATED IN THE
CHICAGO REGION

A STUDY IN ANIMAL ECOLOGY

By
VICTOR E. SHELFORD

The University of Illinois

'

I.

PUBLISHED FOR THE GEOGRAPHIC SOCIETY OF CHICAGO

BY

THE UNIVERSITY OF CHICAGO PRESS
CHICAGO • ILLINOIS

1

COPYRIGHT I9I3 AND I937 BY THE GEOGRAPHIC
SOCIETY OF CHICAGO. ALL RIGHTS RESERVED. PUB-
LISHED OCTOBER I913. SECOND EDITION MAY I937

COMPOSED AND PRINTED BY THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS, U.S.A.

PREFACE

Courses in field zoology usually lack the convenient background of
organization which one finds in the doctrine of evolution when presenting
the animal series from a structural standpoint. The need of some
logical and philosophical background for the organization of natural
history instruction into something more unified than haphazard dis-
cussions of such animals as were encountered in chance localities, was
keenly felt at the beginning of the author's experience as a teacher of
field zoology. Evolutionary background was tried, but failed and was
rejected; genetics and faunistics proved inadequate. Behavior as
presented and studied by zoologists was incomplete. Plant ecological
methods were, when unadapted, applicable only in part, while much
of physiology dealt with organs and internal processes.

The organization of the data here presented is the result of many
attempts and failures which at times made the task seem hopeless. The
literature relating to this subject has been written almost exclusively
from points of view which are very different from the one here presented.
It is scattered, and the bibliography has never been brought together.
Accordingly its incorporation here has called for the expenditure of
much time, and often for reinterpretation, which is always fraught with
danger of error. The time consumed in working over the literature has
been great, but, for the reason stated, the amount covered has been rela-
tively small, and the literature in foreign languages has not received its
share of attention. Furthermore, since the bulletin is not written
primarily for investigators, much of the literature not in English has
been omitted from the Bibliography but some of it will be found in the
papers cited. To present such a subject as we have before us without
constant reference to the writings of such naturalists as Buffon, White,
Darwin, Wallace, Bates, Belt, Hudson, Romanes, Audubon, Brehm,
Fabre, Claude Bernard, Huber, Giard, Forel, Schmarda, Janet, Haase,
Mobius, Dahl, and others (35a) seems at first thought quite unjustified,
but a complete study of the works of such men would be almost a life's
work in itself. The writer does not claim to have a detailed knowledge
of all the articles written by these men. He knows them only in part.
Their facts, in so far as they are known to him and relate to the questions
at hand, tend to support the main contentions. But the successful
organization of such a subject depends more upon the investigation of

vi ANIMAL COMMUNITIES

the particular species and localities covered than upon work done from
different points of view in remote localities. This bulletin is not intended
as a textbook. Several years of work would be necessary to give it the
completeness and form which a textbook should have, and the physiology
which should be included in such a textbook is almost entirely omitted.

The organization here presented has in the main grown out of three
lines of thought: (a) the physiology of organisms as opposed to the
physiology of organs (51) 1 ; (b) the phenomena of behavior and physi-
ology, as illustrated by the studies of Loeb (72), much of the data of
which can be related to natural environments; and (c) the organized
comparable data of plant ecology, as set forth by Cowles (58) and
Warming (12). The results of these five years of labor will not be
pleasing to many zoologists because the principles of evolution, heredity,
etc., have not been correlated. Their omission, however, has not been
due to any prejudice against their introduction, but rather to the fact
that they can only occasionally be related to this line of organization.
It was thought also that the complexity of the problems and concepts
here treated made separation a necessity to clearness.

The number of problems thrown open by the investigation is infinite.
Naturalistic observation and survey work could be carried much farther
along the lines here blocked out. The chief lesson which the author has
drawn from his labors is that experimental study, conducted with due
reference to the relations of the animals to natural environments, with
conditions carefully controlled, and a single factor varied at a time, is
one of the stepping-stones to future progress. We are confronted with
centuries of animal and human geography, with only inference or specu-
lation as to controlling factors for a background, and the experimental
study of factors in the case of man and other land animals only at its
beginnings. Though man is a land inhabitant, all the best work along
these and many other lines has been done upon aquatic animals. The
writer's course in the future will probably be determined by the needs
of the science, and will be turned from the purely naturalistic method
of study to a method made up of naturalistic observations and con-
trolled experiments.

In undertaking a new line of work, one must have first, inspiration,
next, method and motive, and finally, in the case of ecological work, the
assistance of a large number of persons in various departments of
knowledge. For such assistance I wish to express my indebtedness to

1 Numbers in parentheses, scattered through this work, refer to references in the
Bibliography at the end (pp. 325-36).

PREFACE vii

the following: to Professor C. M. Child, of the University of Chicago,
for my first serious inspiration in natural history, and for my oppor-
tunity to develop ecology; he has also rendered important assistance
in connection with the preparation of this work, by giving information
regarding animals about Chicago; his assistance with the worms and
other lower invertebrates has been of particular importance; to Dr. H. C.
Cowles, of the University of Chicago, for constant assistance with the
plants and all matters relating to plant ecology. Various graduate
students and assistants at the University of Chicago have also aided
materially in the preservation of notes, specimens, and records. Mr.
Beniah H. Dimmot, Dr. W. C. Allee, Mr. G. D. Allen, Mr. S. S. Visher,
and Mr. M. M. Wells should be mentioned especially. Mabel Brown
Shelford collected the data on the former occurrence of animals now
extinct, and on other historical matters.

The following have furnished identifications and important advice
in connection with the various groups in which they are specialists:

Dr. N. A. Harvey, Ypsilanti, Mich., Sponges.

Dr. R. C. Osburn, Columbia University, Polyzoa.

Dr. J. P. Moore, University of Pennsylvania, Leeches.

Mr. F. C. Baker, Chicago Academy of Sciences, Mollusca.

Dr. C. D. Marsh, U.S. Department of Agriculture, Copepods.

Mr. Richard W. Sharpe, Brooklyn Institute, Ostracoda.

Dr. Chauncey Juday, University of Wisconsin, Cladocera.

Dr. E. A. Ortmann, Carnegie Museum, Crayfishes.

Miss A. L. Weckel, Oak Park, 111., Amphipods.

Miss Harriet Richardson, U.S. National Museum, Isopods.

Mr. O. F. Cook, U.S. Department of Agriculture, Myriopods.

Dr. R. H. Wolcott, University of Nebraska, Water Mites.

Mr. Nathan Banks, U.S. Department of Agriculture, Spiders.

Mr. C. A. Hart, University of Illinois. All groups of insects.

Dr. J. G. Needham, Cornell University, Aquatic insects.

Dr. Cornelius Betten, Lake Forest University, Caddis-flies.

Mr. W. J. Gerhard, Field Museum, Hemiptera and general entomology.

Mr. A. B. Wolcott, Field Museum, Beetles.

Prof. H. F. Wickham, University of Iowa, Beetles.

Dr. Joseph Hancock, Chicago, Orthoptera.

Mr. W. S. Blatchley, Indianapolis, Orthoptera.

Dr. A. D. MacGillivray, University of Illinois, Sawflies and insect larvae.

Dr. S. E. Meek and Mr. S. F. Hildebrand, Field Museum, Vertebrates.

Mr. Alexander Kwiat, Chicago, Lepidoptera.

Miss Clara Cunningham, South Bend, Tamarack Swamps.

Dr. Frank Smith, University of Illinois, Annelids.

viii ANIMAL COMMUNITIES

Mr. S. S. Visher and Mr. Ralph Chaney contributed most of the habitat data
on birds. Dr. R. M. Strong verified those included here which were
also compared with Butler's account (108). T. C. Stephens supplied the
photographs of nests.

Dr. P. G. Heinemann, University of Chicago, Bacteria.

Dr. Susan P. Nichols, Oberlin College, Algae.

Mrs. Elva Class and Mr. M. M. Wells of the University of Chicago, and Dr.
W. C. Allee, of the University of Illinois, Gas analysis.

Mariner and Hoskins, Commercial Chemists, Analysis of Water.

The original records upon which the work is largely based could not
all be presented. Those placed at the end of the chapters are believed
to be representative, in that they include some characteristic animals,
some which are numerous but occur elsewhere also, and some of wide dis-
tribution. The records in the text are also largely original, except in the
case of mammals, the habitat locations of which are based upon literature.
Mr. W. H. Osgood of the Field Museum has assisted in the editing of the
data on mammals. Original records in this group are especially indicated.
Data on the nesting habits of birds have likewise depended upon compila-
tion, though the locality records are those of the persons mentioned.
Mr. W. S. Stahl, assistant United States attorney, edited the paragraphs
on the legal restrictions upon field study and collection of animals.

The matter of scientific names is one presenting unusual difficulties
because of the scattered and incomplete character of catalogues. The
work of identification having occupied several years 2 changes in nomen-
clature may have led to some confusion and duplication of records under
different names. The matter of correcting spelling is unusually difficult
because of numerous w r orks which it is necessary to consult for verification
in dealing with representatives of nearly all groups from Protozoa to
mammals. The specialists on the different groups have been very kind
in answering any question, but the final responsibility rests with the
author. In the main the nomenclature in the following works has
been followed (numbers refer to Bibliography at the end of this work) :
mammals, 21; birds, 108; reptiles, 157, 157a/ Amphibia, 139 and 152;
fishes, 79; flies, Aldrich's ('00) Catalogue (N.A.); beetles, 156 and
Samuel Henshaw's ('85) checklist; Hemiptera (Heteroptera), Bank's ('n)
Catalogue; aquatic insects, 95 and 96; ants, 54; insects not included
in the special lists, 177; Hymenoptera not in 177, E. T. Cresson's ('87)
Synopsis; spiders, 159; Phalangidae and land mites, 172 and 184; water-
mites, 149; myriopods, 183; mollusks, F. C. Baker's ('06) Catalogue
for Illinois; leeches, 91a; crayfishes, 101, 101a; amphipods, 102; isopods,

PREFACE ix

182; copepods, 146, 146a; ostracods, 147; other Entomostraca, Herrick
and Turner's ('95) synopsis for Minnesota.

In the case of several names not included in any of these works there
are contradictory spellings, authors, etc., and we have used some name
which we believe will be understood.

In bringing together the illustrations, material assistance has been
rendered as follows:

Dr. S. W. Williston, loan of Figs. 30, 31, 32, 126, 132, 174, 186, 187, 188, 210,
267, 269, 270, 271, 272, 273, 274, 275, 282, 283, 284, 285, 286, from his
Manual of North American Diptera.

Dr. F. R. Lillie and the Biological Bulletin, loan of Figs. 66, 67, 68, 69, 8s, 84,
85, 101, 251, 252, 253, previously published by the author in the Biological
Bulletin.

Professor S. A. Forbes, the Illinois State Laboratory, and the State Ento-
mologist's Office, loan of Figs. 35, 36, 44, 45, 46, and 72, which appeared in
Vol. Ill of the Natural History Survey of Illinois, and for electrotypes of
Figs. 261, 262, 264, 265, 288, 289, 290, 291, 292, 296, 297, 301, 302, 303, 304,
305, 306, which appeared originally in the Annual Reports and Bulletins
of the State Entomologist and other state and national publications.

Professor S. E. Meek and the Field Museum, loan of Fig. 37.

Professor J. M. Coulter and the Botanical Gazette, loan of Fig. 115.

Professor F. L. Washburn and the Minnesota State Entomologist's Office for
electrotypes of Figs. 136, 137, 156, 189, 194, 211, 212, 213, 229, 256, 263,
266, 268, 276, 277, 278, 293, 298, 299, 300.

Professor Vernon L. Kellogg, privilege of using Figs. 188, 270, 271, 274 from
North American Insects, which appear also in Williston's Manual of
North American Diptera.

Professor J. H. Emerton, privilege of using Figs. 207, 208, 224, 225 ixom.Com-
mon Spiders.

Figures after Lugger appeared originally in Bulletins $f, 66, and 6g and the
Fourth Annual Report of the Minnesota Agricultural Experiment Station.

Figures after Marlatt, Riley, and Chittenden appeared originally in publica-
tions of the U.S. Department of Agriculture; after Gorham, Smith,
Jennings, and Reighard, in publications of the U.S. Fish Commission.

The author is also indebted to Dr. J. P. Goode, Dr. Otis W. Caldwell,
Dr. H. C. Cowles, Professor R. D. Salisbury, Professor C. M. Child,
and Mr. M. M. Wells for assistance in editing the manuscript and read-
ing proof. Mr. W. J. Gerhard rendered special assistance in the reading
of the proof of the scientific names.

It is evident from the number of persons who have assisted in the
working over of material and the accumulation of the data on which this

X ANIMAL COMMUNITIES

work is based, that the survey aspect of ecology is a subject for co-
operative investigation. Because of the complexity of the problems, it
has been deemed advisable to publish this work even in its present
preliminary and necessarily incomplete form, in order to make the
material accessible as soon as possible to teachers, investigators, and
others who are interested.

Department of Zoology

University of Chicago

September 9, 1912

PREFACE TO THE SECOND IMPRESSION

The second impression of this book is unchanged except for the
correction of typographical and clerical errors. An annotated Biblio-
graphical Appendix has been added which will enable the reader to go
on with the subject. The community nomenclature has changed
materially in the twenty-five years which have elapsed since the book
was written. These changes are, however, not serious and it has been
possible to provide for the correction of them in a table. These cor-
rections were previously published in the journal Ecology. The taxo-
nomic nomenclature has been left in the original form. In many cases
the species mentioned have been separated as two or more, and the
natural areas on which the book is based have, to a considerable extent,
been destroyed so that it would not be possible to discover the relation
of species now recognized. The termites afford an example of this
kind since several species now take the place of what was considered
one in 191 2. Their arrangement, however, makes even a better case
of distribution correlated with succession than was indicated by the
supposed single species.

The author is indebted to Dr. W. C. Allee and Dr. A. E. Emerson
of the University of Chicago for suggestions regarding the Bibliographical
Appendix and to the Illinois Natural History Survey for the loan of a
halftone block. Dr. Allee also provided notes on the stations described
on pages 52-56. Station 30a has an automobile road through its center
and is partially filled and Stations 37, 44, and 49 are no longer available
for study, while Station 42 is now occupied by buildings.

Department of Zoology

University of Illinois

March 4, 1937

TABLE OF CONTENTS

PAOE

Introduction i

CHAPTER

I. Man and Animals 5

I. Introduction 5

II. The Struggle in Nature 6

III. Man's Relation to Nature : . . . 8

IV. The Economic Importance of Animals 20

II. The Animal Organism and Its Environmental Relations 22

I. Nature of Living Substance 22

II. The Relation of Form or Structure to Function .... 22

III. The Basis for the Organization of Ecology 23

IV. Scope and Meaning of Ecology 32

V. Communities and Biota S3

III. The Animal Environment: Its General Nature and Its
Character in the Area of Study 42

I. Nature and Classification of Environments 42

II. The Important Factors and Their Control in Nature . . 43

III. History of the Region about Lake Michigan .... 44

IV. Extent and Topography of the Area Considered ... 48
V. Climate and Vegetation of the Area 49

VI. Localities of Study (Guide) 50

VII. Legal Aspects of Field-Study 56

IV. Conditions of Existence of Aquatic Animals .... 58

I. Introduction: Comparison of Land and Aquatic Animals 58

II. Chemical Conditions 58

III. Physical Conditions 60

IV. Elementary Food Substances 65

V. Quantity of Life in Water 67

V. Animal Communities of Large Lakes (Lake Michigan) . 73

I. Conditions 73

II. Communities of the Lake 73

III. Summary 81

VI. Animal Communities of Streams 86

I. Introduction 86

II. Communities of Streams 86

III. Special Stream Problems 105

xi

Xli ANIMAL COMMUNITIES

CHAPTER PAGE

VII. Animal Communities of Small Lakes 124

I. Introduction 124

II. Communities of Small Lakes 125

III. Succession in Lakes 133

VIII. Animal Communities of Ponds 136

I. Introduction 136

II. Area of Special Study 136

III. Communities of Ponds 140

IV. Succession 151

IX. Conditions of Existence of Land Animals 157

I. Introduction 157

II. Soil 157

III. Atmosphere 159

IV. Combinations or Complexes of Factors 161

V. Quantity of Life on Land 166

X. Animal Communities of the Tension Lines between Land

and Water 169

I. Introduction 169

II. Communities 169

III. General Discussion 183

XI. Animal Communities of Swamp and Flood-Plain Forests 189

I. Introduction 189

II. Swamp Forest Formations and Associations 189

XII. Animal Communities of Dry and Mesophytic Forests . 209

I. Introduction 209

II. Forest Communities on Clay 209

III. Forest Communities on Rock 217

IV. Forest Communities on Sand 218

V. Mesophytic Forest Formation 233

VI. General Discussion 247

XIII. Animal Communities of Thickets and Forest Margins . 262

I. Introduction 262

II. Low Forest Margin Sub-Formations 262

III. High Forest Margin Sub-Formations 268

IV. General Discussion 274

XIV. Prairie Animal Communities 278

I. Introduction 278

II. Prairie Formations 278

III. General Discussion 295

CONTENTS xiii

CHAPTER

PAGE

XV. General Discussion 299

I. Introduction 299

II. Application of the Laws Governing Animal Activities to

World and Regional Problems 299

III. Agreement between Plants and Animals 304

IV. Relations of Communities 308

V. General Relation of Communities of the Same Climate . 311

VI. Relations of Ecology to Other Biological Subjects . . . 315

VII. Relations of Ecology to Geography 318

Appendix: Methods of Study 321

Bibliography 325

Bibliographical Appendlx 337

Index of Authors and Collaborators 345

Index of Subjects 349

INTRODUCTION

Just at the beginning of the present century, there seems to have
been a revival of interest in plants and animals in relation to their
environments, and various workers have turned from the study of
anatomy and classification in the laboratory to the study of organisms in
nature. In this, the botanists have preceded the zoologists, in success
if not in time. In 1901 Dr. H. C. Cowles published a bulletin on the
Plant Societies of the Chicago Area. This was one of the first attempts of
an American biologist to treat all the plants of a given area in a strictly
ecological manner. This study of all the organisms of an area, from the
point of view of their relations to each other and to their environment,
is still a new or at least a renewed idea. Zoologists have devoted most
of their attention to the study of animals from the standpoint of a single
individual and of single species. Practically all of the more general
study has been comparative. We have comparative anatomy, compara-
tive embryology, comparative physiology, and comparative psychology.
These are comparisons of the structure or physiology of one species, or
group of species, with that of another species or group of species.

Our point of view is very different. We shall deal with many species
from the standpoint of their dependence upon each other and their
relations to their environments. We shall attempt to present what has
been learned upon this subject during several years of investigation and
field teaching. In the spring of 1903, the writer made his first field
excursion in the Chicago area, and from that time has been engaged in
further study of the subject.

The study of organisms in relation to environment is entitled ecology.
The definition of ecology, like that of any growing science, is a thing to
be modified as the science itself is modified, crystallized, and limited. At
present, ecology is that branch of general physiology which deals with the
organism as a whole, with its general life processes, as distinguished from
the more special physiology of organs (51), and which also considers the
organism with particular reference to its usual environment.

Undertaking such a study from the point of view of many organisms
involves matters of both ecological and taxonomic classification. Classi-
fication of animals is difficult because animals are so exceedingly numer-
ous. There are probably from 10,000 to 20,000 species of animals which
the naturalist may encounter in the area which we are treating, while

2 ANIMAL COMMUNITIES

in the same area the botanist would probably find only about 2,000
conspicuous plant species. Representatives of all animal species must
be submitted to specialists for identification, that is, the specialist
gives the correct scientific name to the animal. Scientific names are
definitely arranged as below, if man is taken as an example.

Phylum - Chordata or Vertebrata

Class ----__ Mammalia

Order Primates

Family - Hominidae

Genus - Homo

Species ------- sapiens

The young of many insects and of some other animals cannot be
placed in the proper species because animal life histories are very imper-
fectly known. Such animals are merely placed in the proper genus or
family. The common names of animals rarely apply to single species
but to whole genera, families, or even orders. " Caddis-worm " is a name
applied to a whole order of insect larvae and as these are very imper-
fectly known the term caddis-worm is applied to many species, and,
applied in this way, appears in many places in the text.

Because of the large number of animals and the difficulty in naming
them, it is quite impossible to deal with the data in the specific way that
might be possible with plants. Furthermore, while the data for plant
distribution are not well known, those for animal distribution are much
less well known. Therefore in most cases it is necessary to speak in
general terms. It is impossible and undesirable to discuss each com-
munity of animals in detail. The facts are not known, and even if they
were known, their volume would be such as to exclude the great majority
of them from the limits of this treatise. In most cases it is best to make
a statement of the leading facts, and a few statements about the specific
situations to give an idea of the kinds of animals that are characteristic
or common there. It should be noted also that the most characteristic
animals are often not generally known and are in some cases rare.

The scientific names of characteristic and common animals are
included, not so much for geographers at present, as to form a basis for
further work and comparison by zoologists and zoogeographers. Where
given in the form of tables they present the actual scientific background
for the facts here stated. Much greater detail would be needed for a
full zoological treatment. Scientific names are usually used where the
common names apply to many species. The names of authors of species
are added in the text and description of figures only where they do not

INTRODUCTION 3

appear in either the lists and tables or in the descriptions of figures. No
attempt has been made to include the same animals in the text, tables,
and illustrations, as the only aim has been to make each part as useful
as possible.

While the amount of work that might have been done along the lines
here represented is infinite, this work represents only a general survey.
The data are incomplete, but we believe them to be adequate for the
purpose of illustrating the principles involved. Considerable experi-
mental work has been conducted with reference to animal communities, 1
but it has served only as a background, and in comparing them we
have relied upon comparison of (a) habitats and (b) species. The latter
is fraught with many dangers, for it assumes, in the absence of evidence
to the contrary, that the physiological character of a species is the same
in the different situations in which it is taken. Observation has shown
this to be true for most species within rather uncertain limits. There
are, however, many well-known exceptions to this, some of which are cited
in the text. Such use of species is certainly to be avoided in the study
of the extensive or geographic distribution of animals, and it remains
to be seen how far it may be employed locally. Certainly ecology cannot
reach its best development if it relies upon such a method. Whatever
further investigation may prove on this point, it is hoped at least that
we may be able to suggest problems which may be attacked from new
points of view. Should this object be accomplished, the work will have
served its purpose.

J The term community, as used here, refers to all the animals living in the same
surroundings.

CHAPTER I

MAN AND ANIMALS
I. Introduction

I. CULTURE AND NATURE

In this discussion we are concerned with nature and our relations to
nature.

Nature is an enormous aggregation of things — objects — each having cer-
tain metes and bounds, certain qualities and powers, beyond which it cannot
go. Now, knowledge of nature, sanity toward nature, consists exactly not only
in ever increasing the extent of our inventory of these objects, but of recog-
nizing, without addition or subtraction, that is, accurately and justly, the
forms, the qualities, and the forces of these objects — what they are and what
they are not; what they can do and what they cannot do.

Is there anything worse than mild folly in the belief in the "sea serpent" ?
That depends. If the belief involves the notion "monster," then yes, decidedly,
for the belief is of the self -same kind that has prevented men from being sane,
that has rilled them with dread, in all ages. It is a question, not of nature, but
of state of mind. The person whose mental attitude is such that he easily and
unwittingly puts into the sea from his own consciousness a creature that does
not exist in the sea, and holds it to be as real as those that do exist there, is
also in a state of mind to attribute to all sorts of innocent creatures and persons
qualities and powers they do not have and hold these powers to be as real as
the ones they actually do possess. — Ritter (i). 1

We have all heard of the octopus or devil-fish, with its long arms
covered with powerful suckers, which is always waiting to seize the
unsuspecting, choke and bite him, always grasping with another arm
when the grip of one of them is loosened — suitable symbol of the trust.

A person wading in the water among rocks where there are devil fishes is
about as likely to be attacked and bitten by one of the animals as he is to be
injured by the explosion of a watermelon, when walking through a melon patch.
Both things are possible.

The octopus secretes a great quantity of black fluid and makes use of this
by squirting it into the water to envelop itself in "pitch darkness" against
the approach of enemies. But the fluid is not poisonous, nor the leastwise
injurious to anybody or to any creature, so far as we know.

1 Numbers in parentheses, scattered through this work, refer to references in the
Bibliography at the end (pp. 325-36).

6 MAN AND ANIMALS

In short, the animal is not a "horrid thing," as it is painted in story and
in many a dimly lighted imagination. There is nothing devilish about it.

And here is the moral of the "devil fish ": If there is a corner of your mind
that wants to attribute to the octopus malevolent qualities and powers that it
does not possess, and is content to overlook or deny to it qualities and powers
of interest and beauty that it does possess, mark my word, the same corner of
your mind will tend to treat such at least of your fellow-men as you do not know
well, in the same way. This unfortunate corner of your mind will, like all
other corners, be true to itself — to its own qualities. It is the old impossibility
of blowing hot and blowing cold at the same time. — Ritter (i).

We may accept this as one of our relations to nature and general
culture, and sanity toward nature as one of the benefits to be derived
from study of science and nature.

2. SCIENCE AND NATURE

All biological problems are problems of nature. Evolution became a
problem only when a large knowledge regarding the number and diversity
of animal species had been acquired. This has been the problem around
which most zoological facts have been accumulated. Indeed, most
zoologists have little interest in problems not throwing light on evolution.
The development of zoology has therefore been one-sided. Had geology
clung as closely to the origin of the earth as zoology to evolution, it
would not be the unified science w T hich w r e see it today. The lack of
unity in zoology has been caused in part by the neglect of the aspects
which we are to take up here. In this connection, Thompson (2) has
said of Brehm, one of the older students of natural history: " He [Brehm]
had unusual power as an observer of the habits of animals. His
particular excellence is his power of observing and picturing animal
life as it is lived in nature, without taking account of wdiich, biology is
a mockery, and any theory of evolution a one-sided dogma." It follows
also that sanity in science is dependent upon a knowledge of nature.
Our first steps in the task before us must accordingly be a consideration
of wild nature as it really is. This can perhaps best be accomplished by
comparing the reality with some of our conceptions of it.

II. The Struggle in Nature

The first step toward an understanding of our relation to nature,
or rather the animals and animal communities of natural conditions, is
to acquire a knowledge of the conditions of animals in a state of nature.
There is much literature on this subject, but our conception of the
struggle for existence and the survival of the fittest is too often entirely

STRUGGLE IN NATURE 7

forgotten when we are considering our relation to animals. Nature is
cruel and heartless, and to die to become food of another organism is the
fate of the vast majority of animals. Mr. Roosevelt has said :

Watching the game, one was struck by the intensity and evanescence of
their emotions. Civilized man now usually passes his life under conditions
which eliminate the intensity of terror felt by his ancestors when death by
violence was their normal end, and threatened them during every hour of the
day and night. It is only in nightmares that the average dweller in civilized
countries now undergoes the hideous horror which was the regular and frequent
portion of his ages-vanished forefathers, and which is still an everyday incident
in the lives of most wild creatures. But the dread is short-lived, and its
horror vanishes with instantaneous rapidity. In these wilds the game dreaded
the lion and the other flesh-eating beasts rather than man. We saw innumer-
able kills of all the buck and of zebra, the neck usually being dislocated, it
being evident that none of the lion's victims, not even the truculent wildebeeste
or huge eland, had been able to make any fight against him. The game is
ever on the alert against this greatest of foes, and every herd, almost every
individual, is in imminent and deadly peril every few days or nights, and of
course suffers in addition from countless false alarms. But no sooner is the
danger over than the animals resume their feeding, or love-making, or their
fighting among themselves. Two bucks will do battle the minute the herd has
stopped running from the foe that has seized one of its number, and a buck
resumes his love-making with ardor, in the brief interval between the first and
second alarm from hunter or lion. Zebras will make much noise when one of
their number has been killed; but their fright has vanished when once they
begin their barking calls.

Death by violence, death by cold, death by starvation — these are the
normal endings of the stately and beautiful creatures of the wilderness. The
sentimentalists who prattle about the peaceful life of nature do not realize its
utter mercilessness; although all they would have to do would be to look at
the birds in the winter woods, or even at the insects on a cold morning or cold
evening. Life is hard and cruel for all the lower creatures, and for man also
in what the sentimentalists call a "state of nature." The savage of today
shows us what the fancied age of gold of our ancestors was really like; it was
an age when hunger, cold, violence, and iron cruelty were the ordinary accom-
paniments of life. If Matthew Arnold, when he expressed the wish to know
the thoughts of earth's "vigorous, primitive" tribes of the past, had really
desired an answer to his question, he would have done well to visit the homes of
the existing representatives of his "vigorous, primitive" ancestors, and to
watch them feasting on blood and guts; while as for the "pellucid and pure"
feelings of his imaginary primitive maiden, they were those of any meek, cow-
like creature who accepted marriage by purchase or of convenience, as a matter
of course. — From African Game Trails, by Theodore Roosevelt; Copyright,
1910, by Charles Scribner's Sons (3).

8 MAN AND ANIMALS

III. Man's Relation to Nature

Mr. Roosevelt's statement is quite different from much of the poetry
about nature, still it is a true picture. We live in a man-made nature
from which the conspicuous animals and their deadly struggles have
been eliminated (4, 5). Of the admirers of the beauties of nature I
fancy that many, perhaps the majority, think of it as a series of lawn-
like pastures, well-trimmed hedges, such as finds its ideal expression in
some of the older countries like England.

The trees, round, woolly, ready to be clipped;
And if you seek for any wilderness
You find, at best, a park, a Nature tamed
And grown domestic like a barnyard fowl.

— E. B. Browning, "Aurora Leigh."

The close observer of nature, even in such man-made conditions as in
Bedfordshire or in the Chicago parks, sees all the struggle which Mr.
Roosevelt has depicted for the birds and mammals of primeval conditions.
To kill is nature's first law.

1. man's conduct toward animals
There is much sentimental nonsense about nature, about animals
and cruelty to animals, as well as much actual cruelty and wanton
destruction of useful animals. With some people birds obscure all else
in the animal world. The destruction of squirrels, which are equally if
not more interesting than birds, is sometimes advocated because of their
alleged destruction of birds' eggs. The friend of the squirrel would
plead equally hard for the destruction of certain hawks and owls as
enemies of the squirrel. Certainly all lovers of the insect world might
advocate the destruction of birds to protect their particular zoological
pets.

That birds save the harvests of every season is believed by many.
The student of mammals is equally sure that certain mammals are the
balance wheel, while the herpetologist is convinced of the importance of
snakes, and the entomologist's economic world turns about predatory and
parasitic insects and spiders. The fact is that each view, even thus
extremely stated, contains its elements of truth. The whole truth is
hardly knowable. Each animal is dependent upon many others. The
dependences are so numerous that we find it necessary to isolate par-
ticular animals and construct them into a society of real but limited
relations for purposes of discussion (see p. 170). Still there are a few
things that we can be reasonably sure of. The first is that we cannot

MAN AND NATURE g

interfere with any animals or the habitats of any animals without inter-
fering with many others. The second is that all animals are of some
economic importance. The third, that few animals can be said to be
either wholly beneficial or wholly noxious, excepting those reared or
preserved for their direct utility, and those directly and perniciously
attacking the necessities of man's existence.

Considering the first, we note that civilized man's operations interfere
with animals and animal habitats. His first work is to destroy all large,
dangerous animals. He clears and cultivates the land, bringing death
and destruction to many more, and gradually substitutes domestic ani-
mals for wild game (5a). Vegetarians often argue for the exclusive use
of vegetable food on the ground that animals should not be killed, but
to secure more plants for this purpose they of necessity would clear more
land to grow more corn and thus destroy myriads of animals by methods
more cruel than those of the butcher and huntsman. Our relations to
animals are not simple, but very complex and our conduct often inconsist-
ent. We cease wearing aigrettes because the collecting of them often
leaves young birds to die, and kill every mouse and mole that happens
to come our way, though their young must die as do those of the birds.
Some of us wear leather shoes while arguing for a vegetarian diet because
animals should not be cruelly slaughtered.

Turning to the second and third ideas stated above, we note that
few animals which feed upon a variety of foods, both plant and animal,
can be said to be of any great usefulness, except when the plants eaten
are useless to man. In other words, the good done the farmer by an
animal which eats many insects, including noxious ones, may be offset
by a destruction of grain. Birds eat a variety of food. Those feeding
upon useful plants are not rated as of great economic importance. The
bobolink, for example, eats grain and weed seeds in the spring when
insects are scarce; soft-bodied insects in June and July when seeds are
not available. In August the insects mature and are hard shelled. The
birds now reject them for the grain seeds. This bird, furthermore, eats
that which is available and most easily secured during the different
seasons. This is also true of many, probably the vast majority of
animals. The food of fishes is to a considerable extent determined by
the kind of food available where they are living (6). Ruthven (7) has
found this true of garter-snakes; the same is true of men.

Many animals, birds (8), mammals, reptiles (9), toads (10), and
insects destroy quantities of noxious insects, but along with them many
insects that are enemies and parasites of the noxious ones are also

IO MAN AND ANIMALS

destroyed. The parasites, especially, are often more beneficial to man's
interests than the animals which devour them, and which take good and
bad without the slightest discrimination from our economic point of
view. Because of their destruction of parasitic insects Severin (8) argues
that birds should not be protected. Certain mammals and reptiles often
show a decided superiority over certain birds in this respect, in that they
are strictly predatory and are not directly noxious at any time of year
as are some birds which feed upon grain.

Many animals feed extensively upon insect pests when they are
numerous and accordingly threaten a crop. This is true of spiders,
insects (n), amphibians, reptiles, mammals, and birds (8), especially
those that are largely predatory. This fact is the only sure guaranty
of the economic value of many birds, and is perhaps overworked by the
fanciers of the group. This value belongs equally to certain insects,
so that if birds were not devouring such insects along with pests, these
hexapods would probably be able to put the pests down. The other
vertebrates also would probably be able to put down the pest without
the aid of the birds; Forbes has said that a balance would finally be
reached if all the vertebrates were exterminated (see 26).

In the preceding pages we mention " sanity toward nature."
Sanity toward nature is based upon a full knowledge of available facts.
Partial knowledge, if fully depended upon, is as dangerous as falsehood,
for it leads to false interpretations. We must know nature, not a part,
but the whole, if we wish to treat the simplest everyday problem of
our relations to animals intelligently and justly.

Why protect birds? Is the present attempt justified? In the
answer to these questions all sentimentalism should be laid aside. It
is sometimes urged that birds have a greater aesthetic value than other
animals. This it seems is unjustified unless the songs of some constitute
the justification. Persons with only a small acquaintance with insects,
mollusks, fishes, amphibians, reptiles, and mammals find as much beauty
in these groups as the bird fancier does in his. All groups should be
preserved for their aesthetic value as the appreciation of it depends
entirely upon temperament, 1 training, and especially a knowledge of the

1 A few persons known to the writer are repelled by birds because of their claws,
scaly legs, and other reptilian characters. Many admirers of nature and animals are
not attracted by birds because as a rule they must be seen from a distance. Inquiry
at close range necessitates either shooting or capturing the bird and neither is a par-
ticularly aesthetic operation. In the case of capture, only a short period of necessary
neglect usually renders the surroundings and often also the bird not only not aesthetic

MAN AND NATURE II

group in question. From the economic viewpoint there is not a compiete
agreement as to bird protection. France does not co-operate with Eng-
land in bird protection because her leaders in economic thought (Severin
and others) have ably opposed it on economic grounds; still France is
more progressive than England in agricultural matters. Other things
being equal there are but two more reasons for special measures for the
preservation of birds than for the preservation of reptiles, amphibians,
or insects. First, birds are subject to destruction by reckless gunners.
Second, they are less dependent upon natural conditions on the ground
and are better able to survive after land has been put under cultivation
than some other groups. Many other animals whose diets are varied
have been exterminated or will be so by agriculture, leaving the birds
as the most easy point for protective effort. The protection of birds
should not be urged at the expense of the extermination of other animals
because of their alleged occasional attacks upon birds. The great
danger of acting on partial truth regarding animal interdependences
makes societies for the protection of birds alone scientifically and educa-
tionally unjustified. The protection of all groups should be urged, in
particular through the preservation of the natural features upon which
they depend. It is well to protect fishes from seiners and birds from
gunners but this often only delays their fate. We must also consider
where they will breed a few years hence.

When one comes to love an animal or a group of animals, he is in
no position to draw scientific conclusions regarding it. For this reason
bird enthusiasts are not always to be trusted. It was the persistent
efforts of such "benefactors" which gave us that detestable avian rat,
the English sparrow, the feeding or sheltering of which is now a misde-
meanor in some of our states.

Should we slaughter animals ? As members of a system of nature in
which to kill is the first law, we must answer in the affirmative. Man is
the master of all destroyers. Where are the bison, the beaver, the elk,
the thousand and one denizens of the primeval forest and prairie ? We
scarcely walk over a path or lawn without bringing " death " and "suffer-
ing" to animals of some sort. The crime of their destruction can be no

but malodorous and repulsive. Thus to those who wish to examine objects closely
other animals have a greater aesthetic value. Claims for a greater aesthetic value for
birds must be based upon impressionistic appreciation of them in connection with
landscape. There is no reason to desire or assume that this interest will decrease
with time, but it is reasonable to suppose that with further dissemination of scientific
ideas and methods among the people a comparable amount of more serious interest
will develop in connection with other groups and perhaps with birds as well.

12 MAN AND ANIMALS

crime at all, in so far as the destruction is absolutely unavoidable. The
wanton and useless destruction of animals not condemned as noxious by
years of investigation, though probably not forbidden by the example
of the animal world, is forbidden by the best sensibilities of every civilized
man and woman. When the value of an animal to us is in question, the
animal should have the benefit of the doubt, and we should hesitate
long before introducing animals of supposed value. Certainly, also,
every animal condemned by careful investigators should be destroyed
whenever opportunity is presented. Mistaken and sentimental ideas
cause the killing of many useful animals and the protection of many
noxious ones. The farmer kills snakes and skunks whenever he has the
opportunity, though they are among the most useful animals. Shrews
are master destroyers of mice. Still many people mistake shrews for
meadow mice and destroy them. Likewise the housewife kills the
house centipede, the enemy of household pests, as a dangerous and
repulsive creature even in the absence of any knowledge of the question-
able charge that it bites young infants. Mistakes are not confined wholly
to uninitiated individuals. Misjudgment by the officials of the Brook-
lyn Institute of Arts and Sciences, possibly influenced by the sentiment
of Longfellow's mistaken poem on the " Birds of Killingworth " brought
about one of the first official introductions of the English sparrow. Thus
we see that the complexity of the problem demands careful study and
conservative action.

2. MAN-MADE COMMUNITIES

Animal communities are divisible into primeval or primary com-
munities, and man-made, or secondary communities (12, 13). As has
been noted when civilized man enters a new territory, he first destroys
all large game which threatens himself and his domestic animals. He
then destroys the natural vegetation and other animals by clearing the
timber, burning all woody debris, and plowing and putting out plants
which are entirely new to the region. Under primeval conditions,
plants are arranged irregularly, as roughly indicated by the letters in
Diagram 1 ; after being put to agricultural purposes, they are arranged as
in Diagram 2. The plants are all of one kind and are arranged in rows.
A grove of the original vegetation is sometimes left. The rate at
which these changes take place is directly related to the rate at which
man occupies and cultivates the new territory. As compared with
natural changes, this process is rapid and is accompanied by an equally
rapid decline of primeval or primary communities.

SECONDARY COMMUNITIES

13

heddeb hei cd efg cbe mi
e mefg nm be de fg fgbn
ghi be co dp eqfr gohifb
bdcviwhxgyfzembndoc e ih
efgxny uinh fgbhjnk nsfg
ghia dftghtyb hfj tkibhc
sdftunmgkiuoht hyfgtrdcg
dfgythufbnjks vdg fhtgry
hfgt fhgty sdswaq nfhjdl
ghtyuwiokp fbndhutbs gtu
vdfxzabjfmua fgh yfs j i
edfgrthfinbghb fgvnzxvcb
erffghtjk vbxzzasxscdfge
thigjszxlkm, j hytfsdtrfb

Diagram i. — Showing the arrange-
ment of plants and animals on a plot of
ground under primeval conditions. The
letters are fortuitously chosen to rep-
resent the fortuitous arrangement of
plants and accordingly the animals as-
sociated with them. Thus m, n, x, and
z may be taken to represent oak, maple,
basswood, and cherry, respectively, and
the animals associated with each. The
other letters may be taken to represent
herbs and shrubs and the animals asso-
ciated with them.

edbeddgjcdbgdcgdcbedcdgebc
f eceiejfadfeedefadfcecdede
cbaaaaaaaaaaaaaacb
edaaaaaaaaaaaaaaed
fg aaaaaaaaaaaaaa fg
dcaaaaaaaaaaaaaadc
eb aaaaaaaaaaaaaa eb
dg aaaaaaaaaaaaaa dg
fd aaaaaaaaaaaaaa fd
dc aaaaaaaaaaaaaa dc
ie aaaaaaaaaaaaaa ie
eg aaaaaaaaaaaaaa eg
fci bedfg beg bdg ded jef gdj fc
cgj cde fdedfdfebfcg

Diagram 2. — Showing the arrange-
ment under agricultural conditions.
Here the plants which are put out in
rows are represented by a's arranged in
rows. There are certain animals asso-
ciated with such plants and the a's rep-
resent these also. Land is not usually
cultivated close to the fences and thus
each field is surrounded by a border of
original shrubs, herbs, and sprouts from
the original trees. These and the ani-
mals associated with them are still for-
tuitously arranged.

3. THE DECLINE OF PRIMEVAL COMMUNITIES AT THE HEAD OF
LAKE MICHIGAN

By Mabel Brown Shelford
When the white man first appeared near Chicago no secondary
community existed, as the aborigines lived almost entirely by hunting
and fishing. They cultivated the land only a little, and are accordingly
to be ranked with the larger animals as a part of the original communities.
The Indians of this region were chiefly Potawatomi, although there
were a few Chippewas and Ottawas (14, 15). Early in 1833 (15) about
5,000 assembled in Chicago to treat for the sale of their entire remaining
possessions in Illinois and Wisconsin. A treaty was finally ratified and
in 1835-36 (14, 15) they left the region forever. They settled in Iowa
for a time, but the advancing tide of civilization drove them
farther and farther west. In 1890 (16) the larger part of the Pota-
watomi, about 950, occupied land in Kansas and Oklahoma. The region
about Chicago was particularly adapted to the life of the Indians, and
it was probably an important region for them, as well as their successors.
The innumerable water courses and ponds afforded an abundance of

14 MAN AND ANIMALS

muskrats, mussels, fish, etc., and the larger game of the land was par-
ticularly abundant and diversified, because of the numerous habitats
represented. Unfortunately, a fragmentary record is all we have of the
decline of the primeval communities and the development of the present
ones. These records apply mainly to the large animals of Cook County.
The time of the disappearance from Southern Michigan, Northern
Indiana, and Lake County, Illinois, was probably much later and, with
the exception of the bison, bear, and elk, the more numerous kinds of
game nearly all still occur in the thinly settled portions of Illinois ($a).

The earliest explorers of this region, Marquette, LaSalle, and others,
speak repeatedly of the great abundance of large game (17, p. 34).
LaSalle, in the autumn of 1679, sailed along the western shore of Lake
Michigan until the end of the lake was reached. Landing, he found deer,
bear, and wild turkeys in great abundance. Grapevines loaded with
clusters of ripe grapes hung from the tall forest trees and provided a rich
feast for the bears. Continuing toward the headwaters of the Kankakee
River, one stray buffalo was found sticking in a marsh. It was the
beginning of winter and the remainder of the herd had probably migrated
South, but on entering the headwaters of the Illinois River, in the autumn
of the following year, LaSalle says that he found the great prairies
"alive with buffalo" (18).

The Indians claimed that bison were very plentiful on the prairies
until the Storm Spirit, becoming angry at the Indians, sent a great
snowfall and very cold weather, which drove the buffaloes away and
they never returned (19). The time of the great storm seems to have
been between 1770 and 1780. There is good evidence, however, that
they were found in considerable numbers in this part of the state as
late as 1800 (20). Soon after this they entirely disappeared. As late
as 1838 traces of them were still to be found in buffalo paths, well-beaten
trails, leading generally from prairies in the interior of the state to margins
of large rivers. These paths were very narrow, showing that the animals
went in single file (20).

In 1800 and for many years afterward, bears, deer, and elk, especially
deer, were very plentiful. For some time deer continued to increase with
the population because of the protection found in the neighborhood of
man from the beasts of prey, and the gradual thinning-out of the animals
which preyed upon them (21). Elk had almost entirely disappeared in
1837, although a few were seen occasionally (22, 20, 20a, 23). John
Reynolds, an early settler of Chicago, tells of being one of a hunting
party that wounded an elk (20a). In 1837 bears were seldom seen (20,

SECONDARY COMMUNITIES 15

20a). Panthers and wildcats were found occasionally in the forests (20a).
Beavers and otters, once numerous, had almost gone (20). Among the
rodents, the varying hare disappeared about 1834.

In 1838 timber wolves and coyotes were still numerous (20a). The
deer was the most common prey of the timber wolf, but these failing, they
attacked sheep, pigs, calves, poultry, and even young colts (20). For
some time the increase of wolves kept pace with the increase of live
stock. Reptiles were most common in the heavily timbered country.
As this was cleared, they disappeared, while the prairie reptiles were
destroyed largely by prairie fires.

The coyote disappeared about 1844, while the timber wolf did not
entirely disappear until about ten years later (22). The red fox, quite
common at one time along Lake Michigan, also disappeared from this
locality, about this time, although still found occasionally throughout
the state. The gray fox, once quite common, was no longer to be seen
after 1854 (22). The black bear and badger had entirely disappeared at
the same date, although the latter was still common farther south (22).
The fisher, formerly seen frequently in the heavy timber along Lake
Michigan, was no longer to be found. The mink, skunk, otter, and
weasel were still common (22).

The pocket gopher and the badger, once very abundant, were very
rare in 1854 (22). The Canada lynx and wildcat were still abundant,
but of the panthers a single individual was known to have been seen in
Cook County previous to 1854 (22). The decline and disappearance of the
carnivores was followed by the greatest abundance of the deer. Accord-
ing to Wood (21) the deer began to disappear from Central Illinois about
1865 and had totally disappeared in 1870. Their disappearance from
Cook County probably antedated this. The opossum, at one time not
uncommon in this vicinity, was now rare except in Southern Illinois.
The only trace left of beavers was the remains of their dams in several
streams (22).

4. RECOGNIZABLE SECONDARY COMMUNITIES

We may recognize the following communities in the order of their
degree of difference from the primeval ones:

a) Communities of roadside, fence-row , and abandoned field vegetation.
— These are composed chiefly of animals which commonly inhabit weeds
and thickets along the edges of woods. Since these are most nearly
like the thicket or forest-margin communities treated in chap, xiii,
they are not discussed here.

16 MAN AND ANIMALS

b) Communities of parks and pastures. — The ground and subterranean
animals of both pastures and lawns are (near Chicago) chiefly such
prairie animals as can live under the conditions of close grazing or close
mowing. This type of community is probably better developed in
the pastures than in the parks and lawns. The thirteen-lined squirrel,
the May beetle grub, and the earthworms are among the common
species. On the lawns a few grass-feeding species have a hazardous
existence. On the pasture land prairie animals are more abundant,
and an occasional prairie bird nests in a clump of weeds which the cattle
have not eaten.

Shrubs, when present, are inhabited by the forest-margin species.
The trees present are inhabited by such forest animals as are able
to live without the characteristic ground conditions of a forest and
under the more severe atmospheric conditions. There are various
facts pointing to a difference in the animals attacking trees differently
located with respect to other trees; for example, trees standing alone
in open pastures probably have a very different fauna from trees of
the same species growing in the woods. This has not been fully investi-
gated, however. The trees of the parks and lawns are often somewhat
different from those of pastures, because of the introduction of many
trees not native to the region. The animal communities of trees fre-
quently include species introduced from Europe.

c) Communities of lands devoted to cultivated annuals. — The communi-
ties of farm lands are made up of animals from the prairies, the forest
margin, and marsh vegetation, together with introduced species, such as
the cabbage butterfly, the wheat aphis, the Hessian fly, etc.

d) Communities of orchards. — The communities of fruit-growing lands
are made up of the animals from the wild haw, wild crab, wild plum, and
other forest trees, the greater number of which are commonest on flood-
plains. There are also a number of introduced species.

e) Communities of buildings. — The communities of barns, factories,
and dwellings include the common bedbug (introduced), the silver fish,
the cockroaches (introduced), various buffalo bugs of which several are
introduced; one (Dermestes lardarius Linn.) is dangerous to stored
materials and has been known to eat holes in lead pipe; while various
spiders, centipedes, and camel crickets occur. The house mouse, the
Norway rat, and the English sparrow have all been introduced. About
75 household species are to be expected in and about Chicago.

/) Communities of polluted waters. — In connection with the building
of cities, we always find the introduction of sewage and industrial wastes

SECONDARY COMMUNITIES 17

(24) into streams, ponds, and lakes. The effect of the industrial wastes
differs with their character. Sewage practically destroys all the life of a
stream or lake near the point of entrance, through the introduction of
many poisonous substances, through the increase of carbon dioxide
and ammonia and through the lowering of oxygen content. Nichols (25)
states that the oxygen above the entrance of the Paris sewer into the
Seine was 9 . 23 c.c. per liter, and immediately below 1 .05 c.c. per liter, a
reduction of almost 90 per cent. The typical swift-water fauna of Thorn
Creek at Thornton was reduced to practically nil by the opening of
the Chicago Heights sewage system. The common isopod (Asellus com-
munis) was the only animal able to withstand the conditions. At a
distance from a point of entrance of sewage the amount of plankton
is increased by its introduction because of the nitrogen and other food
for plants which it contains. Forbes (see 5a) reports that the amount
of plankton near Havana in the Illinois River has doubled since the
opening of the Drainage Canal.

5. EQUILIBRIUM IN THE SECONDARY COMMUNITIES

Equilibration means a restoration of balance in the numbers of
contending organisms of the community. For instance, as has already
been noted, the deer reached their maximum number with the correspond-
ing destruction of the carnivores by man. This indicated that the
primeval balance between the carnivores and the herbivores had been
disturbed. An entirely new balance has now been established through
the complete destruction of both the large hervibores and carnivores,
by man. Most of our knowledge of equilibration in communities has
resulted from the study of the secondary communities of parks and
agricultural lands. Concerning these Forbes (26, p. 15) has said:

There is a general consent that primeval nature, as in the uninhabited forest
or the untilled plain, presents a settled harmony of interaction among organic
groups which is in strong contrast with the many serious maladjustments of
plants and animals found in countries occupied by man. [All our serious out-
breaks of insect pests are instances of these maladjustments.]

To man, as to nature at large, the question of adjustment is of vast impor-
tance, since the eminently destructive species are the widely oscillating ones.
Those insects which are well adjusted to their environments, organic and inor-
ganic, are either harmless or inflict but moderate injury (our ordinary crickets
and grasshoppers are examples); while those that are imperfectly adjusted,
whose numbers are, therefore, subject to wide fluctuations, like the Colorado
grasshopper, the chinch bug, and the army worm, are the enemies which we
have reason to dread. Man should then especially address his efforts, first,

18 MAN AND ANIMALS

to prevent any unnecessary disturbance of the settled order of the life of his
region which will convert relatively stationary species into widely oscillating
ones; second, to destroy or render stationary all the oscillating species injurious
to him; or, failing in this, to restrict their oscillations within the narrowest limits
possible. For example, remembering that every species oscillates to some
extent and is held to relatively constant numbers by the joint action of several
restraining forces, we see that the removal or weakening of any check or barrier
is sufficient to widen and intensify this dangerous oscillation, and may even
convert a perfectly harmless species into a frightful pest.

Forbes mentions that cottony scale, a common pest in our parks,
was rare in natural conditions. The close setting of trees has favored
its increase. Close setting is nearly always a factor which has to be
considered.

How do pests arise ? The recent rise of the wheat aphis may be
taken as an example. The spring of 1907 was very warm in the southern
part of the wheat belt, and the grain aphis, which is said to reproduce
freely at temperatures from ioo° F. to below freezing, was accordingly
able to reproduce without interruption from its parasites and enemies,
which do not become active at such low temperatures as occurred.
When the weather grew warmer and the enemies appeared the aphids
were so numerous that the work of the enemies was hardly appreciable.
But since they too, like the aphids, are rapid reproducers, w r ith such
favorable conditions they were able to increase rapidly. With their great
increase the aphids decreased and soon their numbers were far too great
for the available aphid food. The enemies therefore decreased because
of the absence of sufficient food, and this portion of the society was
accordingly restored to an approximate equilibrium. It is to be under-
stood that such an oscillation in the society is far-reaching in its effects.
It has been noted that such oscillations affect the whole community.
The birds and mammals find certain kinds of food abundant and accord-
ingly eat things different from what they do under different conditions.
Such fluctuations in the animal communities are constantly going on.

The whole process may be summarized as follows :

1. Weather conditions unfavorable to enemies and favorable to plant pest.

2. Increase in pest.

3. Increase in enemies.

4. Decrease in pest.

5. Decrease in enemies.

6. Balance.

SECONDARY COMMUNITIES 19

6. DISTRIBUTION OF SECONDARY COMMUNITIES ABOUT CITIES
AND VILLAGES

The secondary communities of the regions about Chicago are those
typical of the forest-border area; some of them are found throughout
the temperate world. The communities in and about cities are not
particularly different from those discussed in general terms in the pre-
ceding pages. This is a topic for special study and we can give but the
briefest outline here.

When a city is in the village stage the communities of barns and
dwellings are crowded together and the area of cultivated land and park
is proportionally larger than in the country. As a village grows into a
city, usually a central area of business houses, factories, and cheap tene-
ments, dominated by the communities of dwellings, succeeds, practically
all others being excluded. This type usually radiates from this center
for a short distance along the principal lines of railroad and river trans-
portation. Except for these narrow radiations, the central business
section is surrounded by a belt of residences, which are of the park-lawn
type, usually with the garden or cultivated type very much reduced
or entirely eliminated. This type extends outward along all lines of
passenger transportation. Toward the outskirts of this, and often
quite irregularly arranged, are vacant lots and squares allowed to grow
up to weeds and shrubs, and which are usually occupied by forest-
margin animals. Outside of and adjoining these is the area of market
gardening on the lower and better soils. Other types of agricultural
land are usually poorly cultivated in the vicinity of cities.

A succession of conditions dominated by one or another of the second-
ary communities may be seen as the pioneer farm passes into the city
stage. The pioneer-farm type is succeeded by the village type, with its
park-lawn and dwelling combination. The village gives way to the
business center, dominated by the "dwelling" animals. As these pro-
cesses take place, a succession of the various grades of human society is
noticeable. In dwellings probably the first resident pest is the clothes
moth. This is probably succeeded by the silver fish and an occasional
cockroach before the succession of the various grades of society has
begun. Cracks appear in the woodwork as the building becomes
"run down," and the introduction of a lower grade of society begins.
The bedbug next makes its appearance and marks the beginning of a
rapid lowering of standards on the part of occupants. The house mouse
makes its appearance and is followed later by rats and vermin which
mark the final stages in the degeneration into a cheap tenement.

20 MAN AND ANIMALS

IV. The Economic Importance of Animals

Why study bugs ? Why waste your time upon that which can bring
in no money? Why study insects, worms, birds, or snakes? These
are questions which are often asked of the zoologist, especially such as
go into the field to study and collect animals and accordingly meet the
public. They are questions which the zoologist seldom can answer to
the satisfaction of the inquirer, who not infrequently thinks the observer,
if alone, is somewhat insane. Indeed, the conduct of one Chicago
entomologist led to a police inquiry into his sanity. His offense was that
of collecting insects under an electric light. The questions above we
shall not attempt to answer here, except by asking, "Why study any-
thing?"

We have already noted the complexity of the problems of our relation
to nature. We have noted the disturbed balance, the ravages of species
introduced by accident and by official act. We have noted that knowl-
edge is necessary as a basis for " sanity toward nature." We have still
to call attention to some of the economic values of animals.

It follows from the nature of the animal community and the close
interdependence of the various species that every species is of some
importance in the chain of food, space, and other relations, and every
species is therefore of some economic importance. A few are of great
economic importance. In addition to this we have certain definite
practical uses and well-known matters of importance attached to each of
the animal groups. Taking the various groups in their taxonomic order,
we note the following:

The protozoa are one of the important sources of food of larger forms.
Also about a half-dozen human diseases are known (27) to be due to them,
and the list is continually growing. The shells of extinct species are
an important part of chalk.

The uses of sponges are familiar. Aside from their importance as
food of other forms, the coelenterates furnish us with corals of all sorts.
Among the echinoderms the starfish is an important enemy of the oyster
and mussel beds (28). The flatworms are important as parasites, many
species having been recorded in the body of man (29). The round worms
are of considerable importance in the same way, and some are serious
enemies of grain. The earthworms are of much value to the soil (30).
The crustaceans are the most important aquatic invertebrates, the
Entomostraca being, from the standpoint of food supply, to the waters
what rooted plants are on the land, one of the things to which nearly all
food interaction can be traced. Some are used as food (lobsters, shrimps,

USEFUL AND NOXIOUS ANIMALS 21

crabs). Some are quite extensively used as fertilizers (horseshoe crabs).
The mollusks, aside from importance to other animals, give us our pearls,
pearl buttons, shell work of all kinds (31), fertilizers, important food, ink,
cuttlebone, etc. (32).

The insects are of such importance that nearly every state and
civilized country maintains an expensive staff of trained men whose
business it is to advise the public in regard to their treatment and to
investigate the relations of insects to industry. Their ravages or fear
of the same are the basis of some of the speculation which enriches some
and pauperizes other speculators in the necessities of human life. Aside
from this we have the numerous products from insects — tincture of
cantharides, honey, wax, lac (33), carmine (34), and cochineal. Many
are used as human food in the tropics (locusts, water-bugs, flies, larvae
of the palm weevil, etc.) . Some few, such as the scorpions, are poisonous.
Many diseases are known to be carried from person to person by insects
and arachnids (cholera, yellow fever, malaria, sleeping sickness, typhoid,
typhus, bubonic plague, mountain fever, perhaps leprosy) as well as a
great host of larger parasites.

We turn now to the vertebrates, which are familiar and their uses
quite well known. From this group we get our leather, furs, animal
oils (snake oil, fish oil, turtle oil, lard, whale oil, skunk oil, woodchuck
oil, neatsfoot oil), all of which have recognition in the markets and some
of which have peculiar properties which adapt them to particular pur-
poses (32). Glue, gelatin, bone meal, fertilizers, bone black, etc., are
extensively used in industries; meats, dairy products, furs, leather, etc.,
are necessities.

We must not, however, fail to call attention to animals as the basis
for nearly all experimental study of life processes, of heredity, of behavior
and psychology, of diseases and their cure and prevention. The public
should disabuse itself of the idea that biological investigators are wasting
their time on bugs, for lower animals are the only material upon which
the problems of our race can be solved, and until we are prepared to sub-
mit ourselves to be used in the solution of our own problems, biologists
will be compelled to use lower animals as material.

CHAPTER II

THE ANIMAL ORGANISM AND ITS ENVIRONMENTAL RELATIONS

I. Nature of Living Substance

The bodies of living plants and animals are made up of living matter
known as protoplasm (35, chap. ii). Protoplasm is a chemical substance
or a mixture of chemical substances. It is very difficult to distinguish
living and non-living matter by definition. However, we experience
little difficulty in separating living from non-living things. This is
because living things usually possess certain definite forms and ability to
reproduce and move (especially animals). They also possess irritability.
This is the property by virtue of which the force applied to living sub-
stance is not in proportion to the force resulting (35, p. 124). One
strikes a horse with a whip ; the energy which the horse exerts in running
is not proportional to the force of the blow, but is far greater.

In considering the environmental relations of animals, we shall
separate our discussion into that concerned with form and that con-
cerned with movement (motor activity) and other functional manifesta-
tions. The term function is understood to cover all action on the part
of the various parts of the organisms, motor activity included (35a,
chaps, vii, viii, and ix).

II. The Relation of Form or Structure to Function

The term animal calls forth a mental picture of activity and
movement. The animals with which we are most familiar are those of
large size, such as fishes, birds, and mammals. They and the groups
to which they belong represent only a very small part of the animal
kingdom, but we may consider one of these familiar animals as an
example of animals in general. The black bass will serve our purpose.

Such a fish is a complicated, highly organized animal (36, p. 183),
possessing many organs, such as fins, gills, teeth, a stomach, an intestine,
a liver, a heart, and a brain and spinal cord harnessed to the rest of the
body by a series of small nerves which control all the organs. The fins,
which are the external organs of locomotion, are sufficient in number to
control the body and force it forward. The muscles which move the
fins must receive nourishment in order to do their work. The nourish-
ment is carried in blood-vessels, and the fluid which bears the nourish-

22

STRUCTURE AND ENVIRONMENT 23

ment is propelled by the heart, which is an organ possessing definite
form and a certain type of activity. In the case of a complex animal
like the black bass, we might elaborate upon the relations of form and
structure to activity and function almost indefinitely. It is obvious
that the two features are related in the bass. When we consider animals
which possess less elaborate structure, the relations become less obvious
upon mere inspection because organs are less clearly differentiated, but
they are still more easily demonstrable through methods employed by
the biologist.

In both the lower and the higher organisms, structure may be con-
trolled by activity. If one cuts off the posterior end or tail of a flat-
worm, a new tail is formed. Professor Child (37) found that if the
animals were permitted to crawl on the bottom of the containing vessels
while the new part was growing, the tail was pointed. If they were not
allowed to crawl, the tail was rounded. There are many other pieces
of experimental work which show that structure may be modified by
function. In but few cases, however, has the modified structure been
found to be inherited.

At present the relations between function and structure have not
been investigated in many cases, but Child has made their relation
quite clear by comparing the organism to a river. " The relation between
structure and function in the organism is similar in character to the
relation between the river as an energetic process and its banks and
channel. From the moment that the river began to flow it began to
produce structural configurations in its environment, the products of
its activity accumulated in certain places and modified its flow." It
deposits and removes, and thus continually "moulds its banks and
bottom, forming here a bar, there an island, here a bay, there a point
of land, but still flowing on, though its course, its speed, its depth, the
character of the substances which it carries in suspension and in solution
all are altered by the structural conditions which it has built up by its
own past activity" (37a). Thus we see that function and structure are
mutually interactive and mutually interrelated, and, for the sake of
clearness only, we shall separate the two rather sharply in our discussion.

III. The Basis for the Organization or Ecology

We have already noted that ecology deals with animal life as lived in
nature, or, in other words, with the relations of animals to their environ-
ments. The question of what aspects of these relations are most im-
portant and best suited as a basis for the organization of ecology at

24 ENVIRONMENTAL RELATIONS

once confronts us. The selection of the basis for organization is the most
important step before us, because if we may judge from the history of
previous attempts, success or failure depends upon this selection. It
appears from the preceding pages that we must choose between emphasiz-
ing structure and form on the one hand, and function and activity on
the other.

I. FORM AND STRUCTURE IN RELATION TO ENVIRONMENT

Each article of furniture in the room where I am sitting, each gar-
ment which I am wearing, and the watch in my pocket were made for
a purpose, and are adapted to the purpose for which they were made.
This is so generally true of everything with which we have to do in our
daily lives that we come to think of the phenomena of nature in the same
terms, often without stopping to consider whether or not it can be true
of nature.

The reading into nature of the idea of purpose and of adaptation has
been a common thing since the earliest records of science (38, pp. 52-56).
Two centuries ago the idea that animals were created to fit their
particular place in nature, just as a watch is made for a purpose, was the
idea held by scientists; indeed, such is often the idea of non-scientific
people today. Later, Lamarck conceived the idea that the animal was
not necessarily adapted to a given place, but became adapted to such a
place by trying to live in that place, or, while not able to do a certain
thing, became structurally able to do that thing by trying to do it, just
as the flatworm's tail becomes pointed, and the blacksmith's arm becomes
strong through use. Lamarck (38, p. 169; 39, chap, vi) believed that
the changes brought about by the uses which the organism made of its
parts were inherited, but science has found chiefly evidence that such
changes in structure are not inherited, and this idea of the origin of
adaptation has been quite generally rejected.

Following Lamarck came Darwin, who conceived the idea that all
the individuals of a species which came into existence were not equally
adapted to the mode of life that was necessary for them and those best
adapted survived. Their characters, being born with the individual,
were inheritable and the adaptation of species to which the individuals
belong became perfected through the destruction of the unadapted.
The destruction of the poorly adapted and the survival of the best
adapted is called " natural selection" or the "survival of the fittest."

Following Darwin, a large number of investigators set to work to
apply his theory to the phenomena of nature in detail. The ideas of

STRUCTURE AND ENVIRONMENT 25

"protective resemblance," "mimicry," and "warning coloration" were
developed (40). The idea of protective resemblance is as follows: A
certain insect is green and lives on green leaves. The natural-selection
observer at once theorizes to the effect that the animal is green because,
at a time when not all the individuals of that species were green, the
birds secured all those not green and left the green ones because they
were difficult to see; now therefore only green ones occur. In the case
of mimicry, one species of insect (or other animal) resembles another.
The theorist finds or thinks that one of them is distasteful to birds and
other animals. He further discovers or concludes that the species not
having a bad odor or taste is not eaten by enemies because it resembles
the distasteful species. The species having the bad odor or taste is the
model. The species not having the bad odor or taste is the mimic.
The mimic arose and attained its perfection because those individuals of
the mimic species which resembled the model species survived.

In the case of warning coloration, the animal supposed to be dis-
tasteful has bright colors. The birds, learning that certain bright
colors are associated with bad tastes, avoid such strikingly colored forms.
Accordingly, the most brilliantly colored distasteful forms survive.

More detailed study in recent years has tended to show such specula-
tions to be of questionable value. Such ideas must remain matters of
speculation at present, because of the difficulty of applying experimental
methods to their study. Based on a theory with few facts to support it,
and not withstanding critical analysis, the ideas of structural adaptation,
including any of the ideas just mentioned, are not a good basis for the
organization of a science of ecology.

The revival of an old idea that animal species arose in places and
by methods unknown, and by chance found places to which they were
adapted, now constitutes the central idea of the most recent theory of
the origin of adaptation and is to be favored as a working hypothesis,
because it may be tested experimentally (41).

Another reason for the inadvisability of attempting to organize
ecology on the basis of structure lies in the fact that structural changes
resulting from stimulation by the environment are rarely of advantage
or disadvantage to the animal, and further that the structure of motile
animals is not readily modified by the environment. A considerable
number of animals are larger or smaller, lighter or darker, according
to conditions surrounding them during development (42), but few
biologists see any advantage or disadvantage to the animal in these
changes.

26 ENVIRONMENTAL RELATIONS

2. FUNCTION AND ACTIVITIES IN RELATION TO ENVIRONMENT

We have just noted that from the point of view of structural adapta-
tion, structure cannot be separated from function. It is equally true
that from the point of view of physiology, function and behavior cannot
be separated from structure.

Turning again to the black bass, which we have already used to
illustrate some points, we note that for the simple act of swimming, the
digestive tract, gills, heart, blood-vessels, brain, and muscles are neces-
sary. They must all be present to furnish the animal with the necessary
energy and impulses to make motions for swimming. It is obvious that
there is a division of labor between the different organs, and if any of
them are impaired or injured, or interfered with, the work cannot go on
in its proper manner, or perhaps not at all. The organism is a complex
of correlated parts and processes. If we interfere with any of these, e.g.,
the circulation of the blood of the fish, which might be done in many
ways, the whole system of interdependent processes is interfered with.
The fish is a highly organized animal, but the same general laws of
relations of processes, such as respiration, circulation of food materials,
digestion, etc., apply to animals in which there are no special or definite
organs to take care of each separate process. The interdependence of
processes in the organism is sometimes called physiological proportionality
(37a), i.e., the work accomplished by any one set of organs or processes
is proportional to that of another set or all the sets of processes in the
organism. When the processes are going on in perfect accord and in
proper proportionality, the organism is said to be in physiological equilib-
rium. The conception of the organism stated above may best be used
in considering the relations of animal activities and functions to the
environment.

It is generally held that the various animal forms are made up of
different kinds of protoplasm and that the eggs of no two species are
alike as to protoplasmic character. They may differ only slightly in
appearance, as for example the eggs of a frog and of a salamander, but
even if the eggs of these two animals are laid in the same pool at the
same time, and the conditions are essentially the same surrounding the
two masses, one mass of eggs develops into frogs and the other into
salamanders (43, p. 8). The only logical conclusion is that the composi-
tion or protoplasm of the eggs is different.

It must be noted at the outset, therefore, that different organisms are
made up of different kinds of protoplasm; furthermore, combinations of

ACTIVITY AND ENVIRONMENT 27

the same living substances into different special organs would of necessity
give different organisms different properties.

Different chemical substances often behave differently under a given
condition of temperature, pressure, or light, etc. Likewise, if a cockroach
and a house fly are liberated in the center of a room, the fly goes to a
window and the cockroach into a shadow; furthermore, a cold night will
kill the house fly, while to dispose of the cockroach the proverbial two
wooden blocks are necessary. Both differences in physiological char-
acter (behavior) are due to differences in the organisms. Different
organisms often behave differently in the same intensity of the same
physical factor, for example, the same temperature or light, just as the
different chemical substances do. Different chemical substances often
undergo different changes with variations in temperature, pressure, or
light. Each has its characteristic reactions. Still whole groups may be-
have quite similarly. Changes in conditions affect organisms. We have
all noted the effect of a cool day upon the activity of animals such as the
insects. Different organisms usually behave differently in some respects,
while whole communities may behave quite similarly in other respects.

a) The organism as unaffected by the environment. — When all of the
external conditions continue approximately the same, the activities of
the organism are called spontaneous (35, p. 347). As has been stated,
the organism is naturally active. Accordingly, movements may possibly
take place as a manifestation of the released energy inside the animal,
or of disturbances and changes in the organism which are not directly
initiated by the environment. Probably animals often move without
any external stimulation (44, chap. xvi). One who has observed the
wonderful Japanese dancing mice knows that their constant movement
may not be the result of the external conditions, but of the energy which
is expended within the organism.

Jennings (44) stated that these spontaneous movements must be
recognized in the study of behavior, and that many errors have arisen
from their neglect. If we see an animal moving, we should not assume
that it is moving because of some external condition acting on it at the
time. It may be due to previous stimulation or it may be the result
of internal conditions. Growth, maturity, reproduction, and death are
accompanied by changes in behavior, structure, etc. All may take place
without great change in environment.

b) The organism as affected by the environment. — Many organisms are
not sensitive to slight changes in the external environment. Having

28 ENVIRONMENTAL RELATIONS

developed in, and never having been separated from, fluctuating con-
ditions, they do not respond to all environmental fluctuations. The
terms approximately constant and spontaneous used above are then
both relative. Any change in the external conditions sufficient to alter
the internal processes of the organism is called a stimulus. The visible
movement of the organism or other phenomena resulting from stimulation
is called the reaction. The reaction may be : (a) cessation of movement,
(b) initiation of movement, or (c) change in kind or direction of
movement.

Fluctuations in the environmental conditions in nature usually
involve more than one factor. Experiments are necessary to determine
which factor is affecting the activities of the animal. The effect of the
various factors taken singly upon a few animals has been determined.
These factors are pressure, including currents and contact with other
bodies, shock, vibrations and sound, temperature, water, chemicals, light,
etc. For example, if we lower the temperature surrounding an insect
sufficiently, it will become apparently stiff and lifeless (35, p. 396). If the
temperature is raised again, the animal becomes active. The activity is
increased as the temperature is raised until a degree of heat nearly high
enough to kill it is reached, when the animal becomes inactive again. If
the temperature is raised only a little more, the animal dies. In general
changes in any factor produce either excitation or depression, or in
other words, an acceleration or retardation of the activities. In con-
nection with the acceleration or retardation of activity, animals fre-
quently turn toward or away from the source of light or sound, or in the
direction of a current of air or water. Or they congregate at a point
where the temperature or the light or the chemical conditions interfere
least with their internal processes.

Such turnings or congregations are called tropisms or taxes (45). If
the animals turn toward or go toward the source of stimulation they are
said to be positive. If they turn away or go away or congregate at a
distance they are called negative. The names applied to the reactions
are given below. There are various theories as to the exact manner in
which these turnings and congregations are brought about, but, as a
rule, animals congregate where their internal processes are least inter-
fered with, and random movements nearly always play some part in
the process. There are two sets of terms applied to such responses
as described above; they are given in parallel columns below (p. 29).
Taxis means arrangement. Tropism means turning.

ACTIVITY AND ENVIRONMENT

29

Reactions to light are called phototaxis or heliotropism

temperature are called thermotaxis " thermotropism

moisture are called hydrotaxis " hydrotropism

gravitation are called geotaxis " geotropism

chemicals are called chemotaxis " chemotropism

" contact are called thigmotaxis " stereotropism

" pressure are called barotaxis " barotropism

" electric currents galvanotaxis " galvanotropism

current in medium rheotaxis " rheotropism

If we place a number of common pond snails in a dish which is dark
at one end and grades to sunlight at the other, we find that most of the
snails are found after a time in faint light. The explanation of this
phenomenon is that the snails are stimulated by intense light and by
very weak light, i.e., either of these conditions of illumination interferes
with some of the internal processes of the animal, and the random
movements which result bring the animal into various conditions, one of
which (faint light) relieves the disturbance. The animal then ceases to
move at random, because its internal processes are no longer interfered
with by the stimulus. The snail's activity is lessened, or it turns back
from regions of either too strong or too weak light; accordingly, most of
the snails are found in faint light. The internal processes have been
adjusted or regulated. The snails are said to be negatively phototactic to
strong light and positively phototactic to weak light.

The animal lives in an environment which is constantly changing.
Its spontaneous movements are constantly bringing it into different
conditions. It tends to regulate its internal processes by selecting the
point in the environment in which its internal processes are not dis-
turbed. The writer has observed snails in ponds. They move into their
optimum light, i.e., the light which does not disturb them. On dark
days they are found in the light. On sunny days they are found in the
shade of the vegetation. They shift their position according to condi-
tions and their distribution at any given time is a better index of
conditions than the distribution of plants in the same pond.

c) Modifiability of behavior and different physiological states. — We all
know that our actions may be modified by experience. There are but
few people who have not been greatly frightened by some accident
accompanied by a characteristic noise. For days afterward, one starts
at the slightest unexpected noise. His response has been modified.
It is a well-known fact in animal training that an animal may be
" spoiled." A horse may be ruined for some purposes by an accident

3 o ENVIRONMENTAL RELATIONS

which has caused it to run away, for it thereby acquires the habit of
running away. In the lower animals we find the same condition; their
behavior may be modified, but the modifications are less permanent
than in man and other mammals.

Changes within the organism cause approximately fixed environ-
mental conditions to act as stimuli. Changes are going on all the time
within the organism. Such changes may result from growth, maturation
of sexual products, or other causes. The organism may be in physiologi-
cal equilibrium (see p. 26) in a given set of conditions before the devel-
opment of the eggs and spermatozoa begins, but these processes are
accompanied by other great physiological changes, which frequently put
the animal out of adjustment to its surroundings.

The queen ant is in physiological equilibrium in the darkness of the
nest until she becomes sexually mature. She then becomes positively
phototactic, goes toward the light, flies from the nest with the males,
and, being negatively geotactic, stays away from the ground. When fer-
tilized, she at once becomes negatively phototactic, positively geotactic,
and positively thigmotactic. Accordingly she places her body in contact
with the ground, and burrows into it and starts a new colony. The ant
is then in a different physiological state after becoming sexually mature,
and in a third state after fertilization.

3. ENVIRONMENTAL CHANGES

a) Daily changes. — The physiological responses of animals to these
changes have an important bearing on their relation to each other.
Some forms are diurnal, others nocturnal, others crepuscular. Some are
probably active all the time, but move into different positions in the day
and in the night. For example, some pelagic animals (which float or
swim freely in water and are independent of bottom) are numerous near
the surface at night, but migrate to considerable depths during the day,
as a response to light. Many animals bear relations to day and night,
which in some cases may be of an adaptive character. Some forms are
active during the day, and hide themselves during the night, either in
burrows or under suitable objects. Those which simply crawl under
loose objects during the day frequently appear at artificial lights in
the evening.

It is not impossible that there are structures in the bodies of many
animals which are the product of the different conditions of day and night
during critical periods of growth. Thus Riddle (46) has found that the
barrings of the feathers of certain birds are due to low blood pressure at
night (feeble circulation) during the growth of the feathers.

HABITAT PREFERENCE 31

b) Seasonal changes. — These involve great changes in the physio-
logical states. Inactivity is the rule in winter; growth and activity in
the other seasons. The plants and animals of a locality do not all reach
sexual maturity or the greatest growth activity at the same time during
the growing season, but different species succeed each other as the season
advances (47). The food and enemies of a given species, which is present
in an animal community for a large part of the growing season, differ
from time to time.

c) Weather changes. — These constitute fluctuations of conditions
calling forth special types of behavior. Some animals hide when the
wind begins to blow; some burrow into the ground on cool and cloudy
days.

4. HABITAT PREFERENCES

By virtue of being unlike or possessing different properties, the various
animal species require different conditions for the best adjustment
of their internal processes. For example, the carp lives in shallow and
muddy ponds and rivers, while the brook trout lives only in clear swift
streams. These two organisms are able to move about and find places
to which they are suited. The differences between them are clearly
indicated by the differences in the habitats which they prefer.

By observation and by experimentation it has been shown that
animals select their habitats. By this we do not mean that the animal
reasons, but that selection results from regulatory behavior (p. 29).
The animal usually tries a number of situations as a result of random
movements, and stays in the set of conditions in which its physiological
processes are least interfered with. This process is called selection by
trial and error. If animals are placed in situations where a number of
conditions are equally available, they will almost always be found living
in or staying most of the time in one of the places. The only reason to
be assigned for this unequal or local distribution of the animals is that
they are not in physiological equilibrium in all the places. However,
some animals move about so much that it is with some difficulty that we
determine what their true habitats are.

5. THE MOST IMPORTANT ACTIVITIES OF ANIMALS

Animal activities are classified as feeding, breeding, hiding, sleeping,
etc. The strength of a chain is the strength of its weakest link; the
activity which determines the range of conditions under which a species
will be successful is the activity which takes place within the narrowest
limits. This is usually the breeding activity. The breeding instincts

32 ENVIRONMENTAL RELATIONS

are the center about which all other activities of the organism rotate,
and the breeding-place is the axis of the environmental relations of the
organism (6, 48, 49, 50). Migratory birds are our most striking motile
forms. They may migrate great distances, but always come back to the
same kind of area to breed.

Failure to recognize the relative importance of the different activities
is in part responsible for the general unorganized state of our knowledge
of natural history. Investigators have often failed to interpret the
relations of animals to their environments because they have regarded
the records of the occurrence of all stages of the life history as equally
important. They have considered the occurrence of the most motile
stage in the life history as significant, for example the occurrence of an
adult butterfly. Plant ecologists would have met with equal success if
they had studied only the environmental relations and distribution of
wind-disseminated seeds.

We have noted reasons for not putting primary emphasis on structure
and form as a basis for the organization of ecology. The above discus-
sion shows that activities are actually most important, and accordingly
may be used in ecological study. However, since structure and activity
(function) are always correlated, we should never lose sight of the former.

IV. Scope and Meaning of Ecology

I. SPECIES AND ECOLOGY

In practice, species are diagnosed in terms of structures, such as
number and arrangement of bristles, hair, form, color, size, etc. Such
characters are commonly called morphological. In ecology, the morpho-
logical characters of species are of little or no significance. Still, since
habitat preferences are commonly closely correlated with the characters
used to separate species, some progress in ecology can be made by the
study of the distribution and environmental relations of species, but if
this is not carefully checked by experimentation one may constantly
fall into error.

2. MORES — PHYSIOLOGY THE BASIS OF ECOLOGY

As we have already seen, ecology 1 is that branch of general physiology
which deals with the organism as a whole, with its general life processes as

1 The unorganized phases of ecology are sometimes called natural history, biology,
ethology, or bionomics, but usually by men having little understanding of plant ecology
or who for some reason object to the word ecology (see 35a, pp. 18-21). The term
ecology is applied to those phases of natural history and physiology which are organ-
ized or are organizable into a science, but does not include all the unorganizable data

PHYSIOLOGY AND ECOLOGY 33

distinguished from the more special physiology of organs (13, 51). With
these limitations upon the term physiology, what may be termed
physiological life histories (52) covers much of the field. Under this
head fall matters of rate of metabolism, latency of eggs, time and condi-
tion of reproduction, necessary conditions for existence, and especially
behavior in relation to the conditions of existence. Reactions of the
animal maintain it in its normal environment; reactions are dependent
upon rate of metabolism (53 and citations), which may be modified by
external conditions. Behavior reactions throughout the life cycle are a
good index of a physiological life history.

If we knew the physiological life histories of a majority of animals,
most other ecological problems would be easy of solution. The chief
difficulty in ecological work is our lack of knowledge of physiological life
histories. With elaborate facilities these may be worked out in a
laboratory. Ecology, however, considers physiological life histories
primarily in nature, and for this reason the central problem of ecology
is the mores (13) problem. This may be defined as the problem of
physiological life histories in relation to natural environments together
with that of the relations of organisms in communities. The latter is
not a part of physiological life histories, the mores conception being the
broader. An ecological classification is a classification upon a physio-
logical basis, but since structure and physiology are inseparable, we
must not forget the relations of structure to ecology and to ecological
classification. 1

V. Communities and Biota

1. BASIS
Animals select their habitats probably by trial and error. The simple
fact of selection is, we believe, familiar to all naturalists. A given

of natural history. There has never been any attempt to organize natural history
and physiological data into a science under the head of ethology, biology, or bio-
nomics, and the use of these terms will not seem justified until the materials to which
they have been applied are organized into a science.

1 Mores (Latin singular mos), "behavior," "habits," "customs"; admissible here
because behavior is a good index of physiological conditions and constitutes the
dominant phenomenon of a physiological life history and of community relations.
We have used this term just as form and forms are used in biology, in one sense to
apply to the general ecological attributes of motile organisms; in another sense to
animals or groups of animals possessing particular ecological attributes. When applied
in this latter sense to single animals or a single group of animals the plural is used in
a singular construction. This seems preferable to using the singular form mos which
has a different meaning and introduces a second word. The organism is viewed as a
complex of activities and processes and mores is therefore a plural conception.

34 ENVIRONMENTAL RELATIONS

environmental complex is selected by a number of species. All of the
animals of a given habitat constitute what is known as an animal
community; all the life (plant and animal) is a biota. It follows that
there is often a certain physiological or ecological similarity in the species
which select the same or similar habitats. When not ecologically
similar, animals living in the same or similar habitats are usually
ecologically equivalent, i.e., they meet the same conditions in different ways.
For example, in a swift stream, the small fishes known as darters maintain
themselves against the swift current by their strong swimming powers
and by orienting against the current (positive rheotaxis). The snails
(Goniobasis) are able to maintain themselves because of the strength of
their foot and positive rheotaxis. The darters and snails are ecologically
equivalent with respect to current.

There is a marked agreement of all the animals of this community in
their reactions to the factors encountered in the stream. This agreement
is due (a) to the selection of the habitat through innate (instinctive)
behavior (40, 49, 54, 55), and (b) to the adjustment of behavior to the
conditions through the effects of physical factors and through formation of
habits and associations (44, 53).

Animals of the same species show behavior differences in different
habitats (44, chap, xxi; 55, p. 584; 53). Bohn found that the sea
anemones living near the surface of the sea, where the wave and tide
action are strongest, showed more marked rhythms of behavior in relation
to tide than those living lower down where the action of the tide and
waves is less marked (53a, p. 156; 53 b, p. 155). These rhythms dis-
appeared slowly when the animals were removed from the tide to the
aquarium. Many such cases are probably to be found in the natural-
history literature. For example, the chipmunk differs in behavior under
different conditions (21, p. 523). Abbot (53c, p. 104) makes a similar
statement about fish. It is apparent then that one species may have
several mores. Different species may sometimes have identical mores;
these cases are usually separated geographically (55, p. 604). In
addition to these relations, the relation of ecology to species is largely a
matter of language, names being necessary as a means of referring to
animals.

The physiological and behavior relations of animals in the same
community are of much importance and are included under (a) inter-
physiology or psychology and (b) inter-mores physiology or psychology,
(a) Inter-physiology. — Tarde (55, citations) is the author of the idea of
inter-psychology — the psychology of the relations of individuals of the

PHYSIOLOGY AND ECOLOGY 35

same species (man). He suggests that the social psychology of man
may be traced to the inter-psychology and physiology of the lower
animals. If this is true, then we can be more certain that the inter-
psychology of the higher forms has developed from the inter-physiology
of the lower forms (55 and citations). To this should be added the
behavior between different species, while acting or living together as
one. In the steppes ecologically similar animals frequently act as one
species. Mr. Roosevelt has said that one of the most interesting features
of African wild life is a close association and companionship often seen
between totally different species of game (3). Mr. Roosevelt shows
the zebra and hartebeest herding together, (b) Inter-mores physiology
(between ecologically dissimilar forms, or antagonistic forms). — The
relations of animals of different size, habits, etc., to one another involve
some of the most striking features of behavior. Much of the behavior
which tends to protect animals from enemies falls under this head. 1

In all cases of modification of behavior by the physical environment
or by relations to other animals of the community and in all cases where
the habitat is selected, the habitat is the mold into which the organism
fits. The study and analysis of the habitat is a necessity as soon as the
selection of habitat and the adjustment of behavior and physiological makeup
to the environment are shown to be general facts. Since habitats are differ-
ent, animal communities occupying different habitats are physiologically
different for the reasons just given.

The relations of the animals which make up communities are
relations of life histories. The life histories of the different species are so
adjusted to conditions that all animals do not reach maturity and greatest
abundance at the same time. Some species continue throughout the
season; for example, mammals because of their long lives, and some
species of aphids or copepods because of their great fecundity and
peculiar physiological makeup. There is a succession of mature or
breeding animals with the change of season. A similar phenomenon
is noticeable in plants. Such succession is called seasonal succession
(47, 56). Different species of the same community come into relation
at different seasons of the year.

Communities are systems of correlated working parts. Changes are
going on all the time as a sort of rhythm much like the rhythm of activity
in our own bodies related to day and night. In addition to this, com-
munities grow by the addition of more species, decline, and finally

1 It is at this point that ecology comes into contact with the theories of natural
selection, adaptation, mimicry, etc.

36 ENVIRONMENTAL RELATIONS

disappear from the locality with changes in environment produced
either by themselves or by physiographic or climatic changes (57, 58).
The general growth or evolution of environmental conditions and
the communities which belong to them, are included under succession.
The word succession is used in three distinct senses. We speak of
(a) geological succession, (b) seasonal succession, and (c) ecological
succession.

a) Geological succession is primarily a succession of species through-
out a period or periods of geological time. It is due mainly to the
dying-out of one set of species and the evolution of others which take
their places, or in some cases to migration.

b) Seasonal succession is the succession of species or stages in the life
histories of species over a given locality, due to hereditary and environic
differences in the life histories (time of appearance) of species living there.

c) Ecological succession of animals is succession of mores over a given
locality as conditions change. If species have relatively fixed mores we
have succession of species. When mores are flexible we may have the
same species remaining throughout, with changes in mores. It is on the
basis of ecological succession that we arrange the data presented in chaps,
iv to xiv and proceed with discussion. The response of the organism
to the condition of the environment is only occasionally or partially
dependent upon ecological succession, but this is the only notable
phenomenon about which habitats and animal communities can be
arranged into a natural order.

2. CLASSIFICATION OF COMMUNITIES

Ecological classification of animals must be based upon community
or similarity of physiological makeup, behavior, and mode of life. Those
natural groups of animals which possess likenesses are the communities
which we must recognize. One community ends and another begins
where we find a general more or less striking difference in the larger mores
characters of the organisms concerned. These communities usually
occupy relatively uniform environments (58a).

a) Ecological terminology (13). — Terminology in ecology is still
unsettled and changing. Groupings have thus far been based upon
similarity of habitat. Habitat likenesses have in general been based
upon general resemblances. General resemblances have not always been
accompanied by similar physical conditions. In general there has
been an agreement in the recognition of strata, of associations as com-

COMMUNITIES 37

munities based upon minor differences in habitats, and formations based
upon larger major differences in habitats.

We give the communities of different orders below with taxonomic
divisions of corresponding magnitude opposite for comparison. With
the exception of the first, these taxonomic groupings do not bear the
slightest relation to the ecological groupings, but are added to indicate
magnitude.

Ecological Groups Taxonomic Groups

(Mos) mores Form (forms) (species)
Consocies Genus
Stratum or story Family-
Association or society Order
Formation Class
Extensive formation Phylum
(Aquatic and terrestrial) (Vertebrates and invertebrates)

Mores, in the technical sense in which the term is used here, are
groups of organisms in full agreement as to physiological life histories
as shown by the details of habitat preference, time of reproduction,
reactions to physical factors of the environment, etc. The organisms
constituting a mores usually belong to a single species but may include
more than one species as specificities of behavior are not significant (13).

Consocies are groups of mores usually dominated by one or two of the
mores concerned and in agreement as to the main features of habitat
preference, reaction to physical factors, time of reproduction, etc.
Example: the prairie aphid consocies. The aphids dominate a group
of organisms which for the most part prey upon them, as, for instance,
certain species of lacewing, lady beetles, syrphus-flies, etc. (13).

Strata are groups of consocies occupying the recognizable vertical
divisions of a uniform area. Strata are in agreement as to material for
abode and general physical conditions but in less detail than the consocies
which constitute them (13).

For example, a forest-animal community is clearly divisible into the
subterranean-ground stratum, field stratum (zone of the tops of the
herbaceous vegetation), the shrub stratum (zone of the tops of the
dominant shrubs), the lower tree stratum (zone of the shaded branches
of the trees), and the upper tree stratum. A given animal is classified
primarily with the stratum in which it breeds, as being most important
to it, and secondarily with the stratum in which it feeds, etc., as in many
cases most important to other animals. The migration of animals from

38 ENVIRONMENTAL RELATIONS

one stratum to another makes the division lines difficult to draw in some
cases. Still, the recognition of strata is essential but a rigid classification
undesirable. Consocies boring into the wood of living trees probably
should be considered as consocies relatively independent of stratification
phenomena (13).

Associations are groups of strata uniform over a considerable area.
The majority of mores, consocies, and strata are different in different
associations. A minority of strata may be similar. The term is applied
in particular to stages of formation development of this ranking. The
unity of associations is dependent upon the migration of the same indi-
vidual and the same mores from one stratum to another at different times
of day or at different periods of their life histories. Migration is far
more frequent from stratum to stratum than from one association to
another (13).

Formations are groups of physiologically similar associations. For-
mations differ from one another in all strata, no two being closely
similar. The number of species common to two formations is usually
small (e.g., 5 per cent). Migrations of individuals from one formation
to another are relatively rare (13).

Extensive formations are groups of formations clearly influenced by a
given climate in the case of land formations and by the topographic age
of a large area and by climate in the case of aquatic formations (13, 58a).

A sub-formation is an association or a poorly developed phase of a
formation. The term is used in comparing communities of the ranking
associations when viewed from the standpoint of physiological differ-
ences but without reference to genetic history. Accordingly the same
community is referred to as an association in the genetic sense and a
sub-formation when the point of view is that of physiological difference
or resemblance.

b) Animal communities of the forest-border region. — The forest-border
region is the western line of demarkation between forest and steppe (see
prairie area of Fig. 8, p. 51). The following is a list of the chief animal
communities of the area about the south end of Lake Michigan. It is
not intended to be complete, but rather to illustrate the use of the terms
with particular reference to the communities to be mentioned later on.
The term community is used in the general sense. Association is
applied to stages in genetic development, with sub-formation as an
alternative as defined above. The classification here presented in outline
is artificial and attempts to combine the historical or genetic with the

COMMUNITIES

39

purely physiological points of view. Accordingly some communities are
mentioned more than once. Others have two names.

I. Stream Communities

i. Intermittent stream communities

a) Intermittent rapids consocies

b) Intermittent pool consocies

c) Permanent pool, or horned dace association

2. Permanent stream communities
a) Spring dominated stages

i) Spring consocies

2) Spring brook associations

3. Creek and river communities

a) Pelagic sub-formation

b) Hydropsyche, or rapids formation (turbulent-water formations)

c) Anodontoides ferussacianus, or sand or gravel-bottom formations

d) Sandy-bottomed stream sub-formation (shifting-bottom sub-
formations)

e) Silt or sluggish-stream communities

1) Sluggish-creek sub-formations

2) Pelagic formations

3) Hexagenia, or silt-bottom formation

4) Planorbis bicarinatus, or vegetation formation

II. Large Lake Communities

1. Pelagic formations

2. Eroding rocky-shore sub-formations (turbulent-water formations)

3. Depositing sandy-shore sub-formations (shifting-bottom sub-forma-
tions)

4. Lower-shore formations

5. Deep-water formations

III. Lake-Pond Communities

1. Pelagic sub-formations

2. Pleurocera subulare, or terrigenous-bottom formation

3. Vegetation formation

a) Leptocerinae, or submerged vegetation association

b) Neuronia, or emerging vegetation association

4. Temporary pond formations

IV. Prairie or Grassland Formation of the Savanna Climate

1 Xiphidium fasciatum, or grassland association of moist ground and

marsh vegetation in the savanna and forest climates
2. Prairie chicken, or high-prairie association of the savanna climate

40 ENVIRONMENTAL RELATIONS

V. Thicket or Forest Margin Sub-Formations of the Savanna and Forest
Climates. Physiological group in the main though the "candlehead"
sub-formation may develop into V, 2, or VI, 7, d

1. Wet-ground thicket sub-formations (lower strata periodically sub-
merged)

a) River deposit or stream-margin thicket sub-formations. Associa-
tion in the development of flood-plain forest

b) Marsh and pond-margin thicket sub-formations (first association
in the development of forests in marshes)

c) Candlehead or moist forest margin sub-formation of the savanna
and deciduous forest climates

2. Straussia longipennis, or high forest margin sub-formation of the
savanna climate (a climatic sub-formation of considerable permanency,
probably not usually a genetic type)

VI. Forest Communities of the Deciduous Forest Climate

1. Elm-ash series of communities

a) Low prairie associations (see IV, 1)

b) Marsh-margin thicket associations (see V, 1, b)

c) Elm-ash associations

2. Tamarack or floating-bog series of communities

a) Low prairie or floating-bog association (pitcher-plant consocies)

b) Marsh-margin thicket associations (see V, 1 , b)

c) Tamarack-forest formations

3. Flood-plain series of communities

a) Terrigenous river-margin associations

b) Stream-margin thicket associations (see V, 1, a)

c) Elm and river-maple associations (not studied)

4. Clay series of communities

a) Cicindela purpurea limbalis, or bare clay association

b) Sweet-clover association

c) High forest margin associations (see V, 2)

5. Rock series of communities (little studied)

a) Bare rock consocies

b) Thicket association (probably high forest margin, V, 2). Later
stages not well represented near Chicago

6. Sand series of communities

a) Lake-margin association

b) Cicindela lepida, or Cottonwood association

c) Cicindela lecontei, or the pine association

d) Ant-lion or black-oak association

7. Climatic forest formation of the deciduous forest climate

a) Birch-maple association of the tamarack-forest series

b) Panorpa, or oak-elm-basswood association of the flood-plain and
marsh-forest series

COMMUNITIES 41

c) Hyaliodes vitripennis, or black-oak, red-oak association of the sand
and other sterile soil series

<T) Cicindela sexguttata, or red-oak, hickory association (climax, or final
forest association of the savanna climate)

e) Wood-frog or beech-maple association (the climax or final associa-
tion of the forest climate)

The evidence for the relations of the different formations and
associations here suggested is presented from time to time in the following
pages, and on the basis of this, is graphically represented in Diagram 9,
on p. 312. where both physiological and genetic relations are indicated.

CHAPTER III

THE ANIMAL ENVIRONMENT: ITS GENERAL NATURE AND ITS
CHARACTER IN THE AREA OF STUDY

I. Nature and Classification of Environments (35a, 55, 58) 1

The environment is a complex of many factors, each dependent
upon another, or upon several others, in such a way that a change in any
one effects changes in one or more others. The most important environ-
mental factors are water, atmospheric moisture, light, temperature,
pressure, oxygen, carbon dioxide, nitrogen, food, enemies, materials
used in abodes, etc. In nature the combinations of these in proportions
requisite for the abode of a considerable number of animals are called
" environmental complexes " (55). It is our purpose to consider animals
as inhabiting environmental complexes, rather than to isolate their
responses to various single factors. The consideration of environmental
complexes in any comprehensive way would consume much space and
require extensive and special knowledge of many fields. Accordingly,
we can present here only the briefest outline of some of the principles of
classification, and the important features.

If one is to understand the most elementary principle of the classi-
fication of environments, he must recognize the distinction between
local and (55, 58a) climatic environmental complexes. Local complexes
are often referred to as secondary or minor conditions or as edaphic or
soil conditions. The climate, and such features as types of vegetation
covering large areas, e.g., steppe, deciduous forest, etc., are commonly
regarded as climatic. Opposed to these, and lying within them, are the
local conditions, such as streams, lakes, soils, exposure, etc, which are
only indirectly dependent upon climate. The idea can be better illus-
trated by the desert than by our own region. For example, in the
Mohave Desert, the climatic conditions may be characterized as hot
and arid. Within this desert are a few streams fed by mountain rain-
fall. These streams are local conditions in themselves, and produce
others, such as moist soil, and types of vegetation which do not belong
to the desert. Within the area about Chicago are represented two
geographic complexes, the savanna and the deciduous forest, and lying

1 Numbers in the text in parentheses refer to references in the Bibliography
(PP. 325-36).

42

FACTORS 43

in and among these are various local complexes. The history to follow
applies particularly to the local complexes. The analysis into factors
applies to both local and climatic.

II. The Important Factors and Their Control in Nature

Little experimentation has been conducted with a view to determin-
ing the relative importance of different factors in the control of animals
within an environmental complex. It is known, however, that moisture
(evaporating power of the air), light, and materials for abode are factors
important in the life of land animals ; carbon dioxide, oxygen, materials
for abode (including bottom), and current, in the life of aquatic animals.
The evidence for these statements cannot be presented here, but will be
given in appropriate places throughout the discussion which follows.

I. THE CONTROL OF FACTORS

This is related to physiography, surface geology, and vegetation.

a) Physiography. — In streams, current and oxygen content are
determined very largely by physiographic conditions. Current is a
function of volume of water and slope of stream bed. Oxygen content
is largely determined by the rate of flow, and therefore is influenced by
physiography. In lakes, oxygen content is determined by the depth,
the temperature, and winds — physiographic factors are again important.
On land, moisture and light are in a measure controlled by physiographic
features. Slope and direction of facing profoundly affect vegetation,
moisture, and light.

b) Surface materials and vegetation. — Materials for abode are largely
the surface soil or rock or the vegetation. Surface soil or rock influences
the moisture. Both moisture and surface materials influence the kind
and amount of vegetation. All are interdependent (35a).

Physiographic features change with time. Erosion changes the
gradient of streams, the width of valleys, the steepness of valley walls
and cliffs, the ground-water level, etc. The weathering of rock is a
process familiar to all. It is the aggregate of processes by which the
coarse and hard or massive materials are reduced to clay and soil. This
requires time.

The fact that vegetation grows upon the so-called sterile, coarse
rough-surface materials, usually scattered or ephemeral at first, but
increasing in denseness with each generation, is also familiar (58).
Plants add organic matter to the soil. This organic matter holds the
water so that moisture increases and plants may increase. With such

44

ANIMAL ENVIRONMENT

changes it is obvious that an area of sterile soil will support more animals
as time goes on, than at the outset, when the conditions were such that
only a few hardy species could live. Here again, then, time is the impor-
tant factor in determining the change of the area, so as to be suitable
for more species (because more species are adapted to live in the result-
ing than in the initial conditions). The length of time which has
elapsed since a given set of surface and physiographic conditions became
exposed to the atmosphere is very important in governing the number,
kind, and distribution of animals in a given area.

c) The value of physiographic form. — Physiographic features are
classified according to their form and their mode of origin. What is the
importance of their forms and modes of origin to the animal ecologist ?
Has a kame or an esker or a valley train any significance so far as animals
are concerned? So far as anyone has been able to observe, the fact
that they possess their particular form is of no significance whatever.
Their relations to present ground-water level, their slope, relation to the
sun, etc., are significant. The amount of surface soil and the denseness
of vegetation are also of very great importance, and conditions in these
respects are usually closely correlated with the length of time that the
structures have been exposed to the atmosphere.

Since age is important, we turn at once to the history of an area in
order to learn the relative age of the various features present. We have
parted company with the physiographer and his discussion of mode of
origin, and are in terested in origins only in point of time.

III. History of the Region about Lake Michigan (59)
1. physiographic history

We will give the briefest possible account of the history of the Chicago
area, following Leverett (59), Salisbury (57, 60), Alden (61), Atwood
(62), Goldthwait (62, 63, 64), and Lane (65).

The most important features of our area were shaped during and
since the glacial epoch. To us, the only important movement of the
ice was that of the last Wisconsin ice sheet. This came to us mainly
from the east and north. It spread out over the great basins now
occupied by the Great Lakes and thence pushed on to the higher rock to
the south of them and reached its southernmost extent in Southern
Illinois.

In retiring from here (Fig. 1) one of the positions in which the
edge of the ice halted corresponded to the present Valparaiso Moraine.
The crest of this moraine extends from the Fox Lake region (see map)

FACTORS

45

\ 4

/' ICE SHEET

i f /^

^H* /J£ //

III; ,{r v|L^>

. %W^^I'

)W$ )M ''^

*s

/C^t^*^ V- -a. J/i_ y^^'s^^^ 1 ^

s ^-^^ ^^^^r

The History of the Chicago Region

Fig. i. — Showing the region of the Great Lakes when the Wisconsin ice sheet
was retreating from its maximum extent (after Atwood and Goldthwait).

Fig. 2. — A part of the same area, showing the drainage of the ice sheet by the
Kankakee and Huron rivers through Dowagiac Lake (from Lane after Leverett).

Fig. 3. — Showing a later stage of the retreat of the ice sheet — the Glenwood
stage (from Lane after Leverett).

Fig. 4. — A later stage of the same — the Calumet stage of Lake Chicago (from
Goldthwait after Leverett and Taylor).

Fig. 5. — A still later stage— probably the Tolleston stage (from Lane after
Leverett) .

Fig. 6.— A post-Tolleston stage (from Goldthwait and Atwood after Leverett
and Taylor) .

46 ANIMAL ENVIRONMENT

southward around the head of Lake Michigan, nearly parallel with the
shore, then northward into Michigan, there turning somewhat more to
the east (Fig. 2) . Beyond the edge of the ice, early lines of drainage were
established and temporary lakes came into existence. All of our south-
ward flowing rivers bore the sediment-laden waters from the melting ice.
The results of this may be seen in the gravel and sand outwash, valley
trains, etc., along the DuPage and other rivers, the more sandy portion
usually being farthest downstream.

In Southwestern Michigan, these early lines of drainage were by
the St. Joseph and the Dowagiac valleys. In the latter a small lake is
believed to have existed (Fig. 2). These waters did not flow into the
south end of the lake, as at present, but united and flowed down the
present course of the Kankakee River. The Kankakee marsh area and
the region at the mouth of the Kankakee (Morris Basin) are believed
to have been occupied by a lake. These basins are surrounded by sand
areas which are probably the oldest in our area of study. Dunes are
said to be present to the south and east of "Lake Kankakee, " a few being
present on the moraine in the extreme southeast corner of our map
(frontispiece).

The next stage was marked by the retirement of the ice from the
position of the Valparaiso Moraine to the present basin of Lake Michigan.
The drainage of glacial waters down the Fox, DuPage, and Upper
DesPlaines rivers stopped (Fig. 3). The lakes to the south and east
probably began to disappear. Later, the St. Joseph and Dowagiac
changed their lower courses and flowed directly into Lake Michigan,
which found an outlet by way of the lower DesPlaines.

Now begins the history treated in the first bulletin of the Geographic
Society (60), and Bulletin 7 of the Illinois Geological Survey and else-
where (6 1 , 6 2 , 63 , 64) . The predecessor of Lake Michigan stood at a level
55 to 60 feet above the present lake. The stage is known as the Glen-
wood stage of Lake Chicago. Cliffs were cut, beaches of sand and gravel
were deposited, and dunes were formed. These are our second oldest
sand and gravel areas. Their position is shown on the map (facing p. 52).

The water then fell to a level of 35-40 feet above the present lake.
This is known as the Calumet stage (Fig. 4). Here again cliffs and
beaches of sand and gravel were formed, and constitute our third in
point of age. These beaches have not been indicated on the map
because their distribution within the state of Michigan has not been
studied by physiographers. In the vicinity of Waukegan they are very
close to the Glenwood beach.

FACTORS 47

The lake again receded, probably to a low level, and readvanced to
a 20-foot level known as the Tolleston stage (Fig. 5). Here the develop-
ment of beaches continued and the cutting of new cliffs was inaugurated.
From these beaches, dunes were developed which are fourth in point
of age. The position of these beaches is not indicated on the map.
The lake is believed to have fallen after this to a level of 60 feet below
the present level of Lake Michigan (60-62), which is known as the Cham-
plain stage. At this time the sea came up the Gulf of St. Lawrence as
far as Lake Ontario. Since the cliffs and beaches of this stage were
again submerged, they are no doubt of some importance to the aquatic
life in Lake Michigan, because they affected slope and bottom locally.
The water rose again to a level 12 to 15 feet above the present lake,
known as the Algonquin or post-Tolleston stage (Fig. 6), which was
followed by a retreat to the present level.

2. THE FORMER CLIMATE AND ANIMALS (66)

During the ice age, the entire region about Chicago was overridden
by the ice, and plants and animals migrated southward. There are at
present a few animal species which inhabit glaciers and ice fields, and
probably such were the only regular inhabitants at that time. The
tundra and coniferous forest were crowded to the southward, and with
them the caribou, musk ox, and other northern animals. As the ice
retreated north of the southern end of the basin of Lake Michigan and
the Lake Chicago stage was inaugurated, a tundra climate no doubt
prevailed in the Valparaiso Moraine. It was probably the breeding-
place of the present tundra species of birds; the home of the musk ox,
the caribou, the snow grouse, and other northern animals. The ponds
grew aquatic plants and probably supported hordes of mosquitoes (2)
and other aquatic insects in summer. Early Lake Chicago is said to
show no evidence of life. If we may judge from Arctic lakes at present,
it had a summer fauna, especially of small crustaceans and probably
some fishes.

As the ice retreated still farther northward, the coniferous forest
displaced the tundra, and the musk ox and caribou were presumably
only winter visitors; the woodland caribou and the moose were probably
regular residents. Conditions in the lake were similar to those of the
preceding stage. By this time a relatively rich flora and fauna probably
existed. Organic material accumulated in the soil, shade was produced,
etc. With the further retreat of the ice, the coniferous forest continued
for a long time, but the plants and animals became gradually more and

48 ANIMAL ENVIRONMENT

more like those of the southern portion of the coniferous forest (67),
and gradually gave way through processes of ecological succession to
the species of the present day. Just preceding our period, the mastodon
roamed over the site of Chicago. The skeleton of one of these was
found in a marsh near Crown Point, Ind., another at Cary, 111.

IV. Extent and Topography of the Area Considered 1

The area which we shall consider has its center at a point 18 miles
east of Lincoln Park. It extends 67 miles (108. 1 kilometers) to the east
and to the west and 40 miles (64. 4 kilometers) to the north and 40 miles
to the south from this point. Measured from the mouth of the Chicago
River it extends 85 miles (137 kilometers) eastward, 49 miles (79 kilo-
meters) westward, 38 miles (61 kilometers) southward, and 42 miles
(68 kilometers) northward. It is 80 by 134 miles (128.8 by 216 kilo-
meters) and contains over 10,700 sq. miles (27,820 sq. kilometers).

The range of altitude in the Chicago area is not great. The lowest
part of the bottom of the lake included in our map is about 80 feet above
sea-level. The highest point on the Valparaiso Moraine is 900 feet
above sea-level, which gives a range of altitude of 820 feet. The surface
of the lake is 581 feet above sea-level. The plain of Lake Chicago is

1 See frontispiece map. The term "Chicago Area" has been applied to regions
varying in extent and direction, according to the points of view and interests of
various authors. Chicago biologists have as yet written but little concerning the
ecology of areas to the east of Millers, Ind. It becomes necessary to go farther from
Chicago every year. The areas in Michigan and Northern Indiana offer the only
substitute for those nearer to Chicago which are being so rapidly destroyed.

The following maps covering the area have been published:

1. Lake Michigan

a) U.S. Hydrographic Office, Maps Nos. 1467-75.

b) U.S. Lake Survey Maps, Custom House Bldg., Detroit, Mich.

2. Land

a) County surveyors often publish maps covering particular counties, e.g.,
LaPorte Co., Ind.

b) Illinois Internal Improvement Committee, The Water-Way Report, Springfield,
1909.

c) Topographic sheets of the U.S. Geological Survey (prepared for much of the
region covered by our map).

d) The U.S. Land Office has maps of the original land surveys which are said to
give roughly the distribution of prairies, forests, and marshes.

e) Rand McNally & Co. publish maps of all local counties.
/) Brown & Windes' (Chicago) map of the Fox Lake Region.

g) Davis, "Peat" (map of marshes), Ann. Rept. Mich. Geol. Surv., 1906.

AREA OF STUDY

49

chiefly between 581 and 600 feet, and presents very little relief. The
lowest point of land on our map is in the valley of the Illinois River
below the entrance of the Kankakee. This is 480 feet above tide, or
101 feet below the level of Lake Michigan. In passing from the lowest
point in the lake shown on our map to the vicinity of Lake Zurich, which
is the location of one of the high points on the moraine, one would
travel 64 miles and make an ascent of only 12 feet per mile on the
average. Indeed, if Lake Michigan were to become dry and its bottom
a prairie, it would appear an undulating plain.

V. Climate and Vegetation of the Area

I. METEOROLOGICAL CONDITIONS APFECTING ANIMALS (68)

The table (I) illustrates the fact that there are some notable differ-
ences between the different parts of our area. Extreme points would

TABLE I

Temperature

Mean Rainfall

Sunshine

Ratio of
Rainfall to
Evaporation

Station

April to September

Year

April
to Sep-
tember

Year

April
to Sep-
tember

Year

July,

1887, to
July,

1888

Mean

Mean of
Maxima

Mean of
Minima

Mean

Chicago. . .
South Bend

62.6
653

70.O
76.3

55-6
54-3

48
49

19-3
18.3

33-4
34 -5

1695
hrs.

2616
hrs.

95%

105%

show greater differences. The evaporating power of the air is probably
one of the best indices of conditions which affect animals. The ratio of
rainfall to evaporation is the only expression of the evaporating power
of the air which has been mapped. Fig. 7 shows this phenomenon in
Central North America, with our area indicated.

2. VEGETATION (69, 70)

Those features of the vegetation which are called climatic must be
discussed first. The two main climatic divisions of vegetation represented
in the Chicago area are savanna including the prairie vegetation, and
deciduous forest. The prairie or savanna, as distinguished from steppe,
is a strip of country (the forest-border area) a few hundred miles wide,
from Athabaska to Texas, where trees, chiefly oak, hickory, basswood,

5o

ANIMAL ENVIRONMENT

and elm, occur in groves and along streams. It has the general form of a
bow, with its central and most eastern point at Chicago (Fig. 8) . To the
east of Valparaiso, Ind., the forest is chiefly beech and maple (see
frontispiece). The types are believed to stand in close relation to
climate, especially to ratio of rainfall to evaporation (Fig. 7). 1

The vegetation of local conditions, as indicated on p. 42, is different
from that of the region as a whole and we are concerned in part with

Fig. 7. — Map showing ratio of rainfall to evaporation in percentages, with area
of special study inclosed in rectangle (after Transeau). Compare with Sargent's
map of the "Forests of North America" (10th Census Report and, Fig. 8 below).

the relations of the animal communities of local conditions to animal
communities of the climatic vegetation.

VI. Localities of Study

In beginning tne investigation of any biological subject from the
point of view of general principles, the most important step is the selec-
tion of the material (animals to be studied). In ecological work we

1 A glance at the map shows us that our area of study is in the center of the
Forest-Border Region.

LOCALITIES STUDIED

Si

have not only this, but we must make a still more important choice,
namely, that of the locality of study. To make this selection one must
possess a good knowledge of animal environments, such as we have
touched upon in the preceding pages.

BASIS OF SELECTION AND SUBDIVISION

Such knowledge can be acquired from texts of physiography and
plant ecology, and from special works on the area at hand. The basis

Fig. 8. — Map showing the location of the plains, savanna (prairie), and forest
regions of North America, with area of special study inclosed in rectangle (from
Transeau after Sargent).

of selection is either that of age or of present conditions, or both. The
points selected for study are called stations. Stations are subdivided
on the basis of plant and animal habitats into substations. The sub-
stations may represent either formations or divisions of formations.
For example, a station like Wolf Lake may be divided into sandy
shore substation, vegetation of open-water substation, and embayment
substation.

2. ENUMERATION OF STATIONS — GUIDE

In the study at hand we have made use of a large number of stations
which are enumerated below and are referred to in the text. The list

52

ANIMAL ENVIRONMENT

of stations and accompanying remarks with the Guide Map may serve
as a guide to the region about Chicago for field students.

List of Stations with Direction and Distance by Rail from the
Mouth of the Chicago River, and Transportation

A. Aquatic Communities

I. Large Lake Communities (chap. v).

Station i. The open water, piers at Jackson Park, 6 miles south.

Station la. The eroding shore, Jackson Park, introduced rocks.

Station 2. The eroding shore, Glencoe, 111., C. & N.W. R.R., 20 miles
north.

Station 3. The depositing shore, Bumngton, Ind., L.S. & M.S. R.R.,
and P. R.R., 22 miles southeast. Pine, L.S. & M.S. R.R.,
24 miles southeast. Boats and launch from fishermen.

II. Stream Communities (chap. vi).

Station 4. Youngest ravines, Glencoe, 111., C. & N.W. R.R., 20 miles

north.
Station 5. Youngest brooks, Glencoe, 111., C. & N.W. R.R., 20 miles

north.
Station 6. County Line Creek, Glencoe, 111., 21 miles north.
Station 7. Pettibone Creek, North Chicago, 111., C. & N.W. R.R.,

34 miles north.
Station 8. Bull Creek, Beach, 111., C. & N.W. R.R., 41 miles north.
Station 9. Dead River, Beach, 111., 41 miles north.
Station 10. Spring-fed streams and springs, Cary, 111., C. & N.W. R.R.,

40 miles northwest.
Station 11. Spring-fed streams and springs, Suman, Ind., B. & O. R.R.,

52 miles southeast.
Station 12. Rock ravine stream, the Sag, Joliet Electric, 22 miles

southwest.
Station 13. Intermittent headwaters, Butterfield Creek, Matteson, 111.,

I.C. R.R., 28 miles south.
Station 14. Small swift permanent stream, Butterfield Creek, Floss-
moor, I.C. R.R., 24 miles south.
Station 15. Larger swift stream and effect of rock outcrop, Thornton,

111., C. &. E.I. R.R., 23 miles south.
Station 16. Permanent headwaters and pre-erosion stream, Hickory

Creek, Alpine to Marley, Wabash R.R., 28 to 31 miles

southwest.
Station 17. Permanent swift stream, Hickory Creek, Marley to New

Lenox, Marley (Wabash R.R. only). New Lenox, C.R.I.

& P. R.R. or Wabash R.R., 31 to 34 miles southwest.

GUIDE MAP OF Till" i III' AGO KIGION

LOCALITIES STUDIED

53

Station 18. Sluggish small stream, North Branch of the Chicago River,

Schermerville, CM. &St.P. R.R., 21 miles northwest.
Station 19. Moderately swift, medium-sized stream, North Branch of

the Chicago River, Edgebrook, CM. & St.P. R.R., 12

miles northwest.
Station 20. Fine gravel bottom, DuPage River, Winfield, C & N.W.

R.R., 28 miles west.
Station 21. Gravel bottom, DesPlaines River, Wheeling, 111., W.C R.R.,

S3 miles northwest.
Station 22. Sandy bottomed streams, headwaters of the Calumet, Otis,

Ind., L.S. & M.S. R.R., 50 miles southeast.
Station 23. Larger sandy stream, Little Calumet, Chesterton, Ind.,

L.S. & M.S. R.R., 42 miles southeast.
Station 23a. Deep river, E. Gary, Ind., M.C R.R., 36 miles southeast.
Station 24. Small and intermittent sandy streams, South Haven, Mich.

(4 miles south), steamer, 80 miles northeast.
Station 25. Small sandy stream, Deep River at Ainsworth, Ind.,

G.T. R.R., 46 miles southeast.
Station 26. Medium sandy stream, Black River, South Haven, Mich.,

steamer, 80 miles northeast.
Station 27. Large drowned sandy stream with marsh border, Deep

River, Liverpool, Ind., P. R.R., 31 miles southeast; boats

at saloon.
Station 28. Sandy large drowned stream, Grand Calumet, Clark, Ind.,

P. R.R. (destroyed by industrial waste), 25 miles south-
east.
Station 29. Sluggish stream of the base-level type, Fox River, Cary,

111.; boats near railroad bridge, C & N.W. R.R., 40 miles

northwest.

III. Small Lake Communities (chap. vii).

Station 30. Wolf Lake (a) Roby, Ind., L.S. & M.S. R.R., P. R. R.,
electric railway from 63d St., and Sheffield boathouse, 15
miles southeast; (b) Hegewisch, L.S. & M.S. R.R., P. R.R.,
or South Shore Electric R.R., boats from Delaware House
(not practicable at low water).

Station 30a. Small lake, Lake George, Ind. Electric railway from Ham-
mond or to Hammond from 63d St., or from Robertsdale,
L.S. & M.S. R.R., P. R.R., 18 miles southeast; boats near
south end of lake. For information regarding Indiana
lakes, boats, etc., see Report of the Indiana Fish and Game
Commission for 1907.

Station 31. Fox and Pistakee lakes, Fox Lake, 111., CM. & St.P. R.R.,
50 miles northwest; boats at all hotels.

54

ANIMAL ENVIRONMENT

IV. Pond Communities (chap. viii).

Station 32. Young ponds, Pond 1, Buffington, Ind., L.S. & M.S. R.R.

or P. R.R., 22 miles southeast (1 mile east from station).
Station 33. Middle-aged pond, Pond 5, Pine, Ind., L.S. & M.S. R.R.,

24 miles southeast (pond at rear of station).
Station 34. Middle-aged pond, Pond 7, Pine, Ind., L.S. & M.S. R.R.,

24 miles southeast (pond to the right in front of station).
Station 35. Mature pond, Pond 14, Clark Junction, Ind., P. R.R.,

23 miles southeast (the fourth pond south of bridge over
P. R.R. tracks).

Station 36. Late mature pond, Pond 30, Clark, Ind., P. R.R., 25 miles

southeast (pond parallel with main street and east of school)
Station 37. Senescent pond, Pond 52, Cavanaugh, Ind., South Shore

Electric R.R., 27 miles southeast.
Station 38. Prairie ponds, Roby, Ind., 26 miles southeast, east side of

Wolf Lake, between second and third icehouses.
Station 39. Morainic pond or small lake, Butler's Lake, Libertyville, 111.,

CM. & St.P. R.R., 36 miles northwest.

B. Temporary Pond and Swamp Communities.

AQUATIC PHASES (CHAPS. VIII AND x)

Station 40. Young artificial temporary ponds, Pine, Ind., L.S. & M.S.

R.R., 24 miles southeast (ponds 1 mile northwest of station).

Station 41. Middle-aged temporary ponds, Pine, Ind., L.S. & M.S. R.R.,

24 miles southeast (ponds 1 mile northeast of station).
Station 42. Prairie temporary ponds, south of Jackson Park, I.C. R.R.,

South Chicago Branch to Bryn Mawr, 10 miles south.
Station 43. Prairie temporary ponds, 81st St. and Stony Island Ave.,

electric railway from 63d St. and Jackson Park Ave., south.
Station 44. Temporary pond of prairie type, but being captured by

shrubs, Pond 90 or 93, Ivanhoe Station, L.S. & M.S. R.R.,

to Gibson, Ind., and G. & I. R.R. to Ivanhoe (1 mile

south of Ivanhoe), 36 miles southeast.

C. Marsh, Forest Margin, and Prairie Communities

Station 45. Low forest margin (see Station 30).

Station 46. Intermediate forest margin, Beverly Hills, C.R.I. & P. R.R.,

12 miles southwest.
Station 47. High prairie, Chicago Lawn, 63d St. electric railway,

1 1 miles southwest.
Station 48. High prairie (some low prairie), Riverside, 111., C.B. & Q.

R.R. or LaGrange electric railway, 12 miles west.
Station 49. Temporary forest pond of early stage, Pond 93, near

Station 44.

LOCALITIES STUDIED

55

Station 50. Strictly temporary forest pond, Pond 92, near Station 44.

Station 51. Spring-fed marsh, Cary, 111., C. & N.W. R.R., 40 miles
northwest.

Station 52. Swamp forest, elm, and ash, Wolf Lake, Roby, Ind., south-
east (same as Station 30).

Station 53. Swamp forest, wood west of Dempster St., Evanston, 111.,
C. & N.W. R.R., elevated, or surface cars, 12 miles north.

Station 54. Tamarack swamp, Mineral Springs, Ind., South Shore
Electric R.R, 46 miles southeast. (For other tamarack
swamps, see map.)

Station 54a. Tamarack swamp, Pistakee, 111., 4 miles south of Fox Lake
(see Station 31).

D. Dry Forest Communities

I. EARLY STAGES (CHAP. Xn)

Station 55. On rock, Stony Island, L.S. & M.S. R.R., 12 miles south
on suburban loop. Also Pullman electric car from 63d St.
and Jackson Park Ave.

11. ox clay (chap, xn)

Station 56. Bluff at Glencoe, 111., C. & N.W. R.R., 20 miles north.
Station 57. On sand, moving dunes. Mineral Springs, Ind. (near Lake

Mich, and Station 54).
Station 58. Lower beach, cottonwood and pine, Pine, Ind. (near

Station 40) .
Station 59. Pine and oak, Miller, Ind., near bridge over the Calumet,

L.S. & M.S. R.R., 31 miles southeast.
Station 60. Black oak (same as Station 59 but near village).
Station 61. Clark, Ind., near Station 28.
Station 62. Cavanaugh, Ind., near Station 37.
Station 63. Black oak, white oak, red oak, near Station 44.

E. Moist Forest Communities
(chaps, xi axd xn)

Station 64. White oak, red oak, hickory, upland forest, near Station 56.
Station 65. Forest on Blue Island, Beverly Hills, C.R.I. & P. R.R.,

12 miles southwest.
Station 66. Youngest flood-plain forest, New Lenox, 111., C.R.I. & Pc

R.R., also Wabash R.R., 35 miles southwest.
Station 67. Early flood-plain forest, near Station 15.
Station 67a. (Near station 71a).
Station 68. Mature flood-plain forest, near Station 48.

56 ANIMAL ENVIRONMENT

Station 69. Elm, basswood, oak, hickory forest, Gaugars (near New

Lenox), 37 miles southwest, Joliet So. Electric R.R. from

Joliet or New Lenox.
Station 70. Oak, hickory, beech, maple, Suman, Ind., near Station 11.
Station 71. Beech and maple, Otis, Ind. ; L.S. & M.S. R.R., 50 miles

southeast.
Station 71a. Beech and maple, Sawyer, Mich., P.M. R.R., 73 miles

east (4 miles southwest).
Station jib. Beech, maple, and hemlock, Sawyer, Mich., P.M. R.R.,
73 miles east (i| miles northwest).

F. Secondary Communities

Station 72. Roadsides, Flossmoor, 111., near Station 14.

Station 73. South Haven, Mich, (see Station 24).

Station 74. Stream contamination, Riverdale, 111., I.C. R.R., 17 miles

south.
Station 75. Pasturing of forests, Beatrice, Ind., C.C. & L. R.R., 45

miles southeast.
Station 76. The growth of a modern city, Gary, Ind.; many lines of

transportation; 27 miles southeast.

VII. Legal Aspects of Field-Study

The student must recognize that legally, when he leaves the public
highway, he usually becomes a trespasser, even though he walks in a
stream bed or along a lake margin. Public property is scarce. Still,
since the cost of prosecution is far greater than the remuneration secured
by it in the way of damages, etc., even the most unreasonable owners
are not inclined to insist upon the enforcement of the laws concerning
trespassing. It should be borne in mind, however, that owners or
tenants are entitled to respect, and that as a usual thing they will not
object to the student's working on their property if they be treated with
courtesy. Damaging gates, fences, etc., should be carefully avoided,
and gates should be left as they are found.

Small wild animals such as insects, snails, etc., are not property,
in the eyes of the law, and an owner would probably not be able to pre-
vent their removal from his land except by trespass procedure. Many
of the larger animals are considered as public property and are therefore
protected by law. In most states nearly all birds are protected by law.
It is usually legal to kill certain game birds in season, and certain con-
demned birds at all times. Game mammals are protected in accordance
with a similar plan. It is usually necessary that a license to shoot be

LEGAL ASPECTS 57

obtained before shooting of any sort be carried on. This would apply
even to the shooting of snakes, lizards, and such animals, as well as
game.

Fishes, turtles, and fresh-water mussels are protected in Illinois,
as are fishes in nearly all states. The use of seines and nets of all sorts,
including hand dip-nets, dynamite, and all other devices for securing
fishes, is usually forbidden. The hook and line is the only exception
in some states. Forbidden equipment is nearly always confiscatable,
and the fines for illegal fishing are usually very heavy.

In some states it is possible to obtain licenses or permits to take
birds, birds* eggs, and sometimes fishes for scientific purposes. For
specific information one should consult the state fish and game warden.

CHAPTER IV

CONDITIONS OF EXISTENCE OF AQUATIC ANIMALS

I. Introduction: Comparison of Land and Aquatic Animals

The conditions of existence of aquatic plants and animals are very
different from those of land plants and animals. Some of the most
important differences are as follows:

a) Water, the surrounding medium, is about 768 times as heavy
as atmospheric air at the sea-level.

b) The necessary gases are in solution in the water and their diffusion
is much less rapid than in the atmosphere.

c) The necessary inorganic salts are in solution in the surrounding
medium.

d) The necessary organic food substances for plants and some of the
carbon compounds necessary for animals are in solution in the water and
are taken directly by the plants and animals (47).

e) Vegetation rooted to the bottom is important in most bodies of
water. In large lakes like Lake Michigan, however, there are very few
attached or rooted plants, and therefore nothing comparable to the
vegetation of the land, or to the plant-eating animals which live on it,
is to be found. Most of the plants float freely in the water. Such
plants are present also, however, where rooted vegetation occurs.

II. Chemical Conditions

I. DISSOLVED CONTENT OF WATER

In order to support animals and plants, water must contain certain
minerals and gases in solution (71). Salts (carbonates, sulphates, and
chlorides) of magnesium, calcium, and sodium and salts of potassium,
iron, and silicon are practically always present in solution in water, and
their presence in definite proportions is essential to the life of the animals
(72). Water without these has been shown to kill fish (71). Dissolved
gases in definite proportions are also necessary.

Gases. — The chief facts regarding the occurrence of gases in nature
and their solubility under experimental conditions are shown in Table II.
The standard method of expressing quantity of gas in solution is in cubic
centimeters per liter at o° C. and 760 mm. of mercury (73). All values
are therefore given in these terms.

58

CHEMICAL CONDITIONS

TABLE II

Showing the Distribution and Solubility of Atmospheric Gases

59

Gas Values in

Cubic Centimeters per Liter

AT O C

and 760 mm. Mercury

Composition

Kind of Water

Having Gas

Gas

of Air in

At Temperature

20 C. 760 mm.

Maximum

Content Given

Percentages

Amounts Found
in Natural Fish

in Preceding

Column

Water Absorbs

Water Absorbs

Waters, Springs

from Air

Pure Gas

Excepted

Nitrogen,

argon, etc. .

79.02

12.32 C.C.

15.00 C.C.

19.00 C.C.

Lakes (74,
P- 152)

Oxygen

20.95

6.28 C.C.

28.38 C.C.

24.00 C.C.

Streams,
lakes, win-
ter, with
green
algae

Carbon

dioxide. . . .

O.03

0. 27 C.C.

901 .00 C.C.

30.00 C.C.

Ponds

Ammonia. . . .

Small traces

Very large

14.00 C.C.

Sewage con-

locally

quantities

taminated

Methane

Small traces
locally

34.00 C.C.

10.00 C.C.

Bottom of
lake in
September
(74,p.ioi)

Nitrogen has little effect upon animals except when present in excess.
Under these conditions in the laboratory, bubbles of the gas accumulate
in the tissues and blood-vessels of fishes and cause death. It is not
certain that such conditions exist in nature (Fig. 9).

Oxygen is usually necessary to the life of animals. Most animals
that have been studied select water with a rather high oxygen content
instead of water with little or no oxygen. The resistance of animals to
lack of oxygen varies in different groups. It has been found that water
with about 6 c.c. of oxygen and 14 c.c. of nitrogen per liter is suitable
for brook trout. Mackinaw trout have been taken in water containing
but 1 c.c. of oxygen per liter (6).

In general, carbon dioxide is a narcotic in its action upon animals.
In small quantities it is a stimulant, especially to respiratory action.
In large quantities it produces anesthesia and death. Several workers
have shown that carbon dioxide is very toxic to fishes. Most aquatic
animals that have been studied turn back when they encounter water
containing large amounts of the gas. This turning away from carbon
dioxide is much more decided than it is in the case of corresponding
differences (2.4 c.c. per liter) in oxygen content. Fishes, for example,

6o

AQUATIC CONDITIONS

turn away when they encounter as small an increase as 5 c.c. per liter
of carbon dioxide. Since a large amount of dissolved carbon dioxide
is commonly accompanied by a low oxygen content as well as other
important factors, the carbon dioxide content of water (strongly alkaline
waters excepted) is probably the best single index of the suitability of
the water for fishes.

Fishes do not turn away from ammonia. Ammonia is rarely present
in any great amount in nature. The effect of dissolved methane is
unknown. Oxygen and nitrogen go into solu-
tion from the atmosphere and oxygen is also
V/fiLrr produced by green plants. The other gases

are produced chiefly by organisms as excretory
and decomposition products.

III. Physical Conditions

I. CIRCULATION

The distribution of dissolved salts and
gases is dependent upon the circulation of the
water, as their diffusion is too slow to keep
them evenly distributed. The circulation of
water in streams is probably such as to keep
all dissolved gases and salts about equally
distributed. The water of streams has been
found to be supersaturated with oxygen (74).
Oxygen is taken up by the water near the
surface. Nitrogen and carbon dioxide are
produced especially near the bottom, and if
the water did not circulate they would be too
abundant in some places and deficient in
others for animals to live.

In lakes, during strong winds (74), there is
a piling-up of water on the leeward side and a
lowering of the level on the windward side. This is usually com-
pensated for by a downward flow of the waters along the bottom,
as shown in Fig. 10. Small lakes with little exposure to the wind
and with considerable depth frequently develop a summer circulation,
such as is shown in Fig. n. Such lakes are without oxygen in the
deeper water in summer (74), and will not support the fishes which are
known to inhabit the deeper water of Lake Michigan; hence we con-
clude that Lake Michigan must have a deep circulation at all times.

Fig. 9. — A marine fish
affected with gas-bubble
disease causing protrusion
of the eyes, due to excess
of dissolved nitrogen in
aquarium water (after Gor-
ham).

CIRCULATION AND TEMPERATURE

61

We have been able to find no record of the amount of lowering of
the waters of Lake Michigan at a given point, by the wind, nor any
discussion of the relations of the surface currents to the effects of winds
and the vertical circulation. The waves of large lakes rise to consider-
able heights, as is familiar to all. They are of much importance in
keeping a large amount of gas in solution in the lake waters.

The current in streams differs from that in lakes in that it is for the
most part in one definite direction, while the lake currents often alternate.
There are backward flows and eddies at various points in streams, in
front of and behind every object encountered in the current (57, p. 124).
On the basis of the current, streams are classified as intermittent, swift,

•w-

C

r

10

"%

■ w

11

; yfiy ^.^y.-^-i 'Bfmfflf.-

Fig. 10. — Showing the circulation of the water in a lake of equal temperature.
W represents the direction of the wind (after Birge).

Fig. 11. — The circulation of the waters of a lake of unequal temperature (after
Birge).

moderately swift, sluggish, and stagnant or ponded. The current
wdthin the same stream differs at different times, and in different places.
As we pass across a stream we find the current swiftest near the surface
in the middle, and least swift at the bottom near the sides.

2. TEMPERATURE

Temperature has always been regarded as of great importance in
the direct control of the distribution of life in water. The tendency of
modern investigation is to show that its influence is of great indirect
importance, and the belief in its direct importance is correspondingly
weakened.

The temperature in a stream is probably about the same at the
various points in any cross-section. The extent to which daily, seasonal,
and weather fluctuations in atmospheric temperature affect a lake is

62

AQUATIC CONDITIONS

determined by the depth. Small lakes with incomplete circulation in
summer are cold at the bottom, being heated at the surface only (Fig. 1 1).
Lake Michigan is a deep lake and none of these fluctuations is felt
throughout (see Table III below and Table IX, p. 74). In summer the
water of the surface is warmed, but if the vertical circulation is what
we suppose it to be, all the heat in the waters flowing downward at the
leeward side (Fig. 10) must be absorbed above no meters. Table III
shows the temperatures recorded by Ward (75); these were evidently
taken at the bottom and do not therefore represent the temperatures
at the same level in the open water, especially those records made in
the shallower situations where the sun's rays can reach the bottom
essentially undiminished in intensity.

TABLE III

Temperature of Lake Michigan

Hour P.M.

Tempera-

Tempera-

Temperature at

Date

Unless

Sky

ture of

ture at

Depth in

Depth

Stated

Air

Surface

Next Column

Meters

Feet

Aug. 16

4:05

Clear

16. 7 C.

18. 3 C.

18. 3° C.

64. 9° F.

5-66

18.6

Aug. 18

9:00 A.M.

Cloudy

18. 9 C.

I 7 .2°C.

16. 7 C.

62.o°F.

11.32

37-1

Aug. 18

12:25

Clear-

16. 7 C.

17. 5° C.

7.2°C.

44. 9 F.

22.63

74.I

Aug. 16

5:10

ing
Clear

16. 7 C.

18. 3 C.

7-5° C

45-5°F.

32.06

105.2

Aug. 25

3: 2 S

20. o° C.

19. 4° C.

7 .2°C.

44-9° F.

43.38

142.3

Aug. 16

12:05

Clear

15. 6° C.

18. 3° C.

*- 2 l9-

41. 3° F.

55-93

183. 5

Aug. 11

10:30 A.M.

Hazy

18. 9 C.

5i°C

4i.i°F.

108. 22

355-0

Aug. 16

1:50

Clear

16. 7 C.

18. 3° C.

4 .2°C.

39-5° F.

1 1 2 . 00

367-5

Aug. 18

4:30

Scat-
tered
clouds

i8.9°C.

18. 3 C.

4. 2°C.

39-5° F.

132.66

436.0

3. LIGHT (76)

Light is an important factor in controlling the distribution and
activities of animals. The depth to which light penetrates water is
therefore of importance. Forel found that in Lake Geneva, Switzer-
land, during the period when the water was clearest, light diminished
gradually from 25 to 65 meters, and then decreased rapidly to 115 meters
where there was not sufficient light to affect the photographic plate.
No doubt future investigation with more accurate means of measuring
light will show that very faint light penetrates much farther. The
depth of light penetration in fresh water is usually determined by the
amount of sediment in the water. Forel found that in Lake Geneva
the depth of light penetration decreased with the melting of the mountain

LIGHT AND PRESSURE

63

snows and the beginning of the rainy season. The drainage area of Lake
Michigan is very small and has little relief, and the amount of sediment
carried in is small at all times. The depth of light penetration is there-
fore not so much influenced by these factors as in Lake Geneva. Wave-
action is also important in stirring the bottom materials near shore.
We would expect the light penetration in Lake Michigan to be least
during the rainy and windy seasons, and greatest in calm, dry weather —
late summer and autumn. 1 All of the surrounding physiographic con-
ditions are factors controlling light. Table IV shows the seasonal
distribution of rainfall and light penetration in Lake Geneva, and the
seasonal distribution of winds and rainfall at Chicago.

TABLE IV

Showing Depth of Light Penetration in Lake Geneva and Conditions Affect-
ing the Same in Both Lake Geneva, after Forel (76, Vol. II,
p. 439), and Lake Michigan
In the eighth column the results are given in seconds, in terms of the effect on the
photographic plate, of equivalent exposures to the sun.

Month

January.. .
February. .
March. . . .

April

May

June

July

August. . . .
September
October. .
November.
December.

Lake Michigan

Rainfall

Inches

2-3

2-5

2.7

3-5
3-7
3-6
2.8

30

2.6
2.6

Centi-
meters

5-1

5-2

6.4
6.9
8.9

9-4
2

2

5-3

Velocity of Wind
at Noon

Miles per
Hour

Meters

per
Second

8.0

Lake Geneva, Switzerland (after Forel)

Rainfall and Light

Prec. in
Cm.

7-4
5-ii

Light
Limit at
Depth in
Meters

no
75
45

50

Light and Depth

Intensity
of Light
(March)
at Depth
in Next
Column

500 sec.
500 sec.
500 sec.
400 sec.
360 sec.
120 sec.

60 sec.

25 sec.

10 sec.
2 sec.
o sec.

Depth in
Meters

O.O
19.6

25.2

45-5
55-5
65.6
75-6
85-7
95-8
105.4
115. 6

4. PRESSURE (76)

Pressure in water increases with depth. The results given by Forel
are shown in Table V.

ir rhe Lake Michigan Water Commission has reported greatest turbidity in
January, February, March, and April.

6 4

AQUATIC CONDITIONS
TABLE V (76)

Pressure in
Atmospheres

1

2

3

5

8

10

20

Depth in meters.

10.328

20.6

3°-9

5i-5

82.4

103.27

206 . 49

It will be noted that there is a little less than one atmosphere
increase in pressure for each 10 meters (33 feet) in depth because water
is very slightly compressible. According to this, animals in the deepest
parts of Lake Michigan are living under a pressure of about 375 pounds
to the square inch.

5. BOTTOM

The character of materials and topography of the bottom are very
important to animals living on the bottom, but it has its effect also on
free swimming animals as a determining factor in the amount of sedi-
ment.

The kind of bottom is important because many animals are
dependent upon solid objects for attachment and are absent from
bottoms made up of fine materials. Others must burrow into mud
or creep on sand and gravel. This will be discussed later in special
cases, particularly in streams.

Topography of the bottom in shallow water is important in lakes
locally in affecting wave-action and currents, and through these, bottom
vegetation and temperature. Ward (75) noted such effects but did
not carry the work far enough to solve any of the problems involved,
which are usually local. In lakes, bottom materials are most important
in shallow water, because of their effect in connection with wave-action,
the amount of sediment in suspension, and the stability of the bottom.
The bottom materials of lakes vary greatly locally. Taking Lake
Michigan as an example, if we were to see the region about Chicago
denuded of all vegetation, we would be able to appreciate the fact that
there are bowlder deposits, gravel deposits, sand, clay, and bare rock.
Evidently the ice sheet left the same kind of bottom materials strewn
with the same irregularity in the bottom of the lake as on the land.
Apparently wave-action has not affected them below 25 meters (85 feet).
The waves of Lake Michigan are believed not to move sand below
9 meters (30 feet). It is thought that, during the Champlain stage, the
lake stood at a level 60 feet below its present level. Along the north
shore there is a cliff at this level with sand deposits lying on the side
toward the deeper water. Inside of this is an area of clay and then, next

VEGETATION AND FOOD SUBSTANCES 65

to the present shore, sand and gravel again. It is seen that this lower
level of the lake influenced both the topography and bottom material
locally, both of which probably have an influence on the occurrence of
certain animals.

6. VEGETATION

The amount and kind of rooted vegetation is very important to
animals. Of all the aquatic situations with which we have to deal
Lake Michigan has fewest attached plants, and these are all algae.
Cladophora, Chara, and filamentous algae are the most important.
These do not appear to have been recorded below about 25 meters;
some of them require solid bodies for attachment, and are probably most
abundant on the rock outcrops of shallow water.

The vegetation of the younger streams consists largely of holdfast
algae like those along the rock shores of the lake. These are of impor-
tance to animals. The more sluggish streams have rooted aquatic
vegetation.

The vegetation is used as breeding-places. Eggs are stuck into plant
tissues by the predaceous diving beetles (Dytiscidae) and by the water
scorpions (Ranatra). Eggs are attached to plants by the electric-light
bugs (Belostomidae), back-swimmers, May-flies, caddis-flies, water
scavengers (Hydro philidae), long-horned leaf beetles (Donatio), snails,
and many fish (Umbra, and probably Abramis). Young animals are
often dependent upon plants for shelter, to escape from enemies, etc.
Many animals must use plants as a means of reaching the surface for
oxygen. The most important of these are the Dytiscidae (adults and lar-
vae), the Hydro philidae (adults and larvae), the back-swimmers, Zaitha,
Belostoma, Donacia, snails, Ranatra, and Haliplidae. Some, for example
Zaitha and dragon-fly nymphs, lie in the vegetation and wait for their prey.

Different kinds of vegetation have different values for animals.
The bulrush is barren for the following reasons: (1) hardness makes it a
bad place for eggs; (2) there are no clinging-places; (3) there is little
shade; (4) it gives a high temperature in summer; (5) there is no great
addition of oxygen by vegetation ; (6) it does not afford a suitable place
for securing food. Equisetum is unfavorable for similar reasons. Elodea
is excellent; Myriophyllum, good; water-lilies and Chara, only fair.

IV. Elementary Food Substances (47)

Nitrogen, in the form of nitrates, is necessary for the growth of the
plants of a pond, lake, or stream, and an insufficient quantity is secured
from mineral soil. Nitrogen can be taken from the air only by nitrogen-

66 AQUATIC CONDITIONS

fixing bacteria, such as Azotobacter, an aerobe, and Clostridium, an
anaerobe. These bacteria occur on the outside of plants and animals,
in the mud of the bottom, etc. Plants and animals provide carbon for
the bacteria; bacteria provide the nitrites or nitrates for the plants.

Ammonia, resulting from the decomposition of proteid of the dead
bodies of plants and animals, is oxidized to nitrous acid; nitrous acid is
oxidized to nitric acid by the bacteria (Nitrosomonas, Nitrobacter, Nitro-
coccus). This acid unites with bases to form nitrates and nitrites.
There are accordingly two sources of nitrate and nitrite. Working
against these are the denitrifying bacteria {Bacterium actinopelte [Baur])
which reduce nitrogen compounds to free nitrogen. Their work is
influenced by temperature. Baur placed a standard quantity of nitrate
infected with Bacterium actinopelte at several temperatures (47, p. 271)
with results as follows:

1. Temperature 25 C: Denitrification began 24 hours after inocu-
lation; in 7 to n days later the solution was nitrate-free.

2. Temperature 15 C: Denitrification began 4 days after inoculation;
in 27 days the solution was nitrate-free.

3. Temperature 4-5 C: Denitrification began 20 days after inocula-
tion; process incomplete 112 days after.

4. Temperature o° C: Denitrification not initiated.

The quantity of life in water has been held by some to be in propor-
tion to the available nitrogen. The amount of plankton in the sea is
greatest in the polar regions in summer. It has been suggested that
the greater retarding effect of low temperature on the denitrifiers, as
compared with the producers of nitrates, is a cause of the greater quantity
of life in colder waters. Atmospheric nitrogen in solution is important
in the building of nitrogen compounds by nitrogen-fixing bacteria.
Oxygen is necessary for the life of most organisms, though a few can
live for considerable periods in its absence. Carbon dioxide is necessary
for starch building by chlorophyll-containing plants and animals.
These organisms form the principal (food) basis of all other organisms.

Complex foodstuffs, such as proteids, are necessary for most animals.
It is only animals which contain chlorophyll in the form of algae living
symbiotically in their bodies, or otherwise, that can live without taking
in proteid from the outside. Proteids are made only when light for the
production of starch, nitrates, and several other inorganic foods are
present. Light is then indirectly necessary to animals which can live
in darkness.

The smaller aquatic animals are commonly either alga-eaters or
predatory. The larger aquatic animals are commonly predatory or

QUANTITY 67

scavengers. The rooted vegetation is eaten only to a small extent.
Small floating or swimming plants and animals, called plankton (Figs.
12-18, pp. 75, 76) are the basis of the food supply of larger animals.
We could probably remove all the larger rooted plants and substitute
something else of the same form and texture without greatly affecting
the conditions of life in the water, that is, so far as the life habits of the
animals are concerned. The aquatic plants are commonly covered with
a coating of green algae, protozoa, and other small organisms, so that
animals such as small snails may rasp the surface of the plants and secure
food without eating the plant tissues themselves. Plants in water are
of particular use to animals as clinging- and nesting-places.

V. Quantity (47) of Life in Water

The quantity of living matter in water, so far as it is plankton or
floating organisms, has been much studied. The quantity is usually
expressed in one of two ways: number of organisms per liter or cubic
meter of water, determined by counting a part of a collection; or in
cubic centimeters per cubic meter of water. In Lake Michigan (August)
Ward (75) found an average of 11 . 5 c.c. per cubic meter in water from
the surface to 2 m. ; from 2-25 m., 3 . 9 c.c. ; 25 m. to bottom, o . 4-1 . 5 c.c.
He found that Pine Lake (a small lake) contained relatively less plankton
than Lake Michigan, the surface stratum of Pine Lake containing more
and the deeper strata much less than the larger lake. Lake St. Clair
contains only one-half as much plankton as Lake Michigan. Lake
Michigan contains only about one-tenth as much plankton as some of the
small European lakes (Dobersdorfer See). Kofoid (77) found 71 .36 c.c.
per cubic meter the maximum record for the Illinois River. The
average for the year is 2.71 c.c. per cubic meter. The largest amount
recorded by Kofoid is 684.0 c.c. per cubic meter (Turkey Lake, Ind.) .

Small streams and lakes with large inflow and outflow have but little
plankton. Large amount of plankton is commonly associated with
high C0 2 content, low oxygen content, and a large amount of carbonate
in solution.

The amount fluctuates from season to season. Kofoid (77) found
the maximum for the Illinois River in April to June. The amount
gradually decreases until December and January, when the minimum
is reached. He also found evidence that the light of the moon increases
photosynthesis and the amount of plankton. The maximum of Crustacea
was found by Marsh (78) to fall in July, August, and September, differing
in different years. The maximum in Lake Michigan probably is usually

68

AQUATIC CONDITIONS

in late summer or early autumn. Smaller bodies of water are similar
in this respect.

I. LAW GOVERNING QUANTITY (47)

Liebig's Law of Minimum, as applied to plants, is stated as follows:
"A plant requires a certain number of foodstuffs if it is to continue to
live and grow, and each of these food substances must be present in a
certain proportion. If one of them is absent, the plant will die; if one
is present in a minimal proportion, the growth will also be minimal.
This will be the case no matter how abundant the other foodstuffs may
be. Thus the growth of a plant is dependent upon the amount of the
foodstuff which is presented to it in minimal quantity" (47, p. 234).
The amount of plankton is determined by the same law. All food sub-
stances must be present in the correct proportions. The amount of
plankton may be determined by one substance which is deficient in
amount.

2. age and quantity (6 and citations)

In bodies of water with small outlet, the quantity of plant and animal
life probably increases with the age of the water body. This is because
the foodstuffs are washed in by the inflowing water, and because rooted
plants absorb food from the soil in which they grow, and when they die
and decay these foodstuffs are added to the water. Accordingly, the
older the pond and the longer rooted vegetation has grown, the greater
the quantity of life. This principle is illustrated by an age-series of
ponds at the south end of Lake Michigan to be discussed in detail later.
The numbers used indicate relative age. Ponds i, 5, 7, 14, 30, 52, 89,
and 95 were studied, but especially 1, 5, 7, and 14 (6). Tables VI- VIII
give a summary of the results.

TABLE VI

Showing Quantitative Results of Examination of Factors Related to
Quantity of Plankton

Pond Numbers — Age-Series

14

No. of
Collection

Total carbonates in parts per million

C0 2 , c.c. per liter*

Oxygen, c.c. per liter*

Bacteria per c.c

138.800
0.0
6.28
779

160. 200
3-4
3-47

2450

160.300
2.7
2.78
355o

•Average of collections, April, May, June, July, taken over sandy bottom (pond i) or at the top
of submerged vegetation (ponds 7 and 14).

QUANTITY

69

We note that on the whole the carbonates, C0 2 , and bacteria are
greater in quantity according to age. Oxygen is on the whole less.

TABLE VII

Showing the Number of Entomostraca in Approximately 90 Liters of Water

Body of Water

September 3, 4

April 30, 1910

Average of
Collections in
Parentheses

Relative Age

Wolf Lake

213

232

4,H5

556

539

2,773

i,o39

35i

2,870

2,900

9,333
19,866
Aug. 28, 191 2
104

133

2,600

1 1 ,400

2,480

1,556 (3)

4,78l (3)

11,991 (3)

874 (6)

927 (6)

2,680 (6)

1

Prairie Pond I

2
3
14

1

7
14
30
52
89
95

Prairie Pond II

Pond 1

Pond 7

Pond 14

Pond 30

Pond 52

Pond 89

Pond 95

TABLE VIII

Showing Ratio of Number or Quantity of Different Organisms When the

Maximum Is 100

Rooted vegetation

Entomostraca

Midge larvae ....

Sphaeridae

Gilled snails

Lunged snafls. . . .

Amphipoda

Crayfishes

Insects

Fish

Pond Numbers — Ecological Age-Series

32
80
O
20
IO

50

IO

40

IOO

60

35
So

50
50
50
go

50
00
87

146

100
100

IOO
IOO
IOO
IOO
IOO
IOO
IOO

87

The Entomostraca are rated on the basis of actual count of six col-
lections. The other figures are estimates (6).

Here we note that the number of Entomostraca was greater in the
older ponds though some irregularities occur, dependent upon the
amount of rainfall. In rainy seasons the increase with age appears
almost throughout.

As we pass from younger to older ponds we note an increase in the
number of animals, excepting fish. These appear to decrease, probably

7o

AQUATIC CONDITIONS

because of the increasing unsuitability of the ponds as fish breeding-
places. The oxygen content decreases, particularly on the bottom.
The distribution of the fish present in these ponds, and whose breeding
habits were known, was found to be correlated with the distribution
of the bottom upon which they breed. This becomes less and less in
amount as the ponds grow older.

3. EQUILIBRIUM

Each animal prefers certain food. The food relations of pond
animals are shown in Diagram 3, below. For purposes of illustration
let us suppose the existence of a community composed of the species
named only.

Black bass adults
Black bass young

Diagram 3. — Showing food relations of aquatic animals. Arrows point from the
organisms eaten to those doing the eating. For explanation see text.

Any marked fluctuation of conditions is sufficient to disturb the
balance of an animal community (see chap, i, p. 18). Let us assume
that because of some unfavorable conditions in a pond during their
breeding period the black bass (79) decreased markedly. The pickerel,
which devours young bass, must feed more exclusively upon insects.
The decreased number of black bass would relieve the drain upon the
crayfishes, which are eaten by bass, crayfishes would accordingly increase
and prey more heavily upon the aquatic insects. This combined attack
of pickerel and crayfishes would cause insects to decrease and the number
of pickerel would fall away because of the decreased food supply. Mean-
while the bullheads, which are general feeders and which devour aquatic
insects, might feed more extensively upon mollusks because of the

EQUILIBRIUM

71

decrease of the former (see chap, i, p. 15), but would probably decrease
also because of the falling-off of their main article of diet. We may
thus reasonably assume that the black bass would recover its numbers
because of the decrease of pickerel and bullheads, the enemies of its
young. A further study of the diagrams shows that a balance between
the numbers of the various groups of the community would soon result.

Diagram 4. — Showing the life histories of the animals of the pond community
in the form of circles. The heavy, vertical, black lines represent the animals which are
dependent upon the most elementary food substances. A represents dead animal
matter; B, the protozoa, rotifers, and Entomostraca, the smallest animal food. The
black lines come into contact with different numbers of life cycles, but are indirectly
connected with all so that any change in the position or rate of movement (meaning
number or rate of reproduction and growth) of the rod must effect the entire com-
munity; compare with Diagram 3.

Diagram 5. — Showing the food relations in the brook community. A repre-
sents algae which grow upon the stones. B represents the floating animal bodies and
other organic matter. The latter are of small importance because of their small
number and the swift current.

Under other circumstances, such as the extinction of the black bass, the
resulting condition would be entirely different from the original one,
but a balance between supply and demand would nevertheless finally
be established. The community is said to have equilibrated when such a
condition is reached; that is, a new equilibrium is established which
may or may not be like the old.

72 AQUATIC CONDITIONS

The causes of fluctuations of numbers of organisms are numerous.
Cold winters often destroy aquatic vertebrates. Large rainfall dilutes
the plankton in streams and carries it away. Too little sunshine causes
a poor production of the chlorophyll-bearing organisms which are the
food basis of all the others. High temperature favors denitrification.
From Diagram 3 and brief discussion above it will be seen that there
are in a pond community, close interrelations traceable to certain groups
which are closely dependent upon the more elementary food substances
A representation of these relations is given in Diagrams 4 and 5.

CHAPTER V

ANIMAL COMMUNITIES OF LARGE LAKES (LAKE MICHIGAN)

1. Conditions

I. GENERAL (75)

Lake Michigan lies between 4i°-4o' and 46°-5' N. latitude. Its total
length is about 350 miles and its greatest width is approximately 85 miles.
Its area is about 25,000 sq. miles. Its greatest depth is nearly 275 meters
(900 ft.) and its average depth is approximately 122 meters (400 ft.).

Within the area covered by our map (frontispiece) there are about
3,200 sq. miles. The maximum depth is about 152 meters (500 ft.).
It has been estimated that the lake contains 262,500,000,000,000 cubic
feet of water. It becomes obvious at once that the lake constitutes one
of the most uniform and extensive environments with which we have to
deal.

2. CIRCULATION

The level of the lake fluctuates from season to season with the
amount of rainfall, but we have been unable to find a statement as to the
amount of such fluctuation. Changes in atmospheric pressure over part
of the lake cause various fluctuations in level, called seiches. In Lake
Michigan there is a definite circulation of the surface waters. Here the
current moves southward along the west shore (57), around the head of
the lake, and northward along the east shore. The rate of flow is 4 to 90
miles per day.

II. Communities of the Lake 1 (80, 81, 82, 8^, 84)

One of the recognizable animal communities of Lake Michigan is
made up of the animals which live freely in the water, either swimming
or floating. This community is called the Pelagic or Limnetic com-
munity. Other communities are governed directly or indirectly by depth

x The only published account of the invertebrate fauna of the Great Lakes is
that of Lake Superior. From this account and from incidental scattered notes found
in various publications cited we have been able to bring together enough data to give
an idea of the conditions and life which we may expect future investigations to show.
The attempts to study Lake Michigan have been ill-fated. In 187 1, the Chicago
Academy of Sciences and the United States Fish Commission co-operated in an
attempt to study the fauna of the lake. The work on the vertebrates was published

73

74

COMMUNITIES OF LARGE LAKES

and bottom. Accordingly the conditions on the bottom at various
depths are roughly shown in Table IX.

TABLE IX

Physical Conditions

Limit of sand-moving waves

Limit of daily temperature fluctua-
tions; limit of wave action; be-
ginning of light decrease; pressure
about 2\ atmospheres

Pressure 4 atmospheres; light re-
duced to I

Seasonal temperature fluctuations
less than i°; light reduced to f ;
pressure sf atmospheres

Light \ ; pressure 7 atmospheres . . .

No light; pressure \\\ atmospheres;
no change in temperature; uni-
form conditions

Greatest depth in the area con-
sidered; pressure 15 atmospheres

Greatest depth in lake; pressure 27I
atmospheres

Depth

Meters

Feet

8

26

25

82

39

128

54

177

70

230

US

377

153

500

274

900

Vegetation

Lowest record of Chara
and (75) Cladophora

Scanty filamentous algae
(75)

Nostoc and diatoms (75)
No bottom plants recorded

No plants recorded
No plants recorded
No plants recorded

I. THE LIMNETIC COMMUNITY

(Station 1 ; List I)
Chicago is famous for its good water supply. However, if one fastens
a small sack of miller's bolting-cloth under an open water tap for an
hour in summer and examines the contents of the sack with the naked
eye and then with the microscope, he will be of the opinion that he has
not been straining drinking water but stagnant ditch water. He finds
small microscopic plants in great numbers (75), as well as large numbers
of small animals, most of the larger ones dead. Every person drinking
water from a lake or river drinks the small plants and animals. If
every one of the 2,000,000 persons in Chicago drank a quart of unfiltered

by the United States Fish Commission, and Doctor Stimpson of the Academy pub-
lished a brief note on the invertebrate forms found in the lake, but never gave more
than a hint of the work, as the collections were all burned with the Academy's build-
ing. Subsequently, collections were made by the State Laboratory of Natural His-
tory, and later by the Fish Commissioners of Michigan. In the summer of 1902, the
University of Chicago and the Academy of Sciences made a single-day excursion,
but no report was ever published.

LIMNETIC COMMUNITY

75

ML

x>

..^•'

■«,->:

mm?

'•'i.-M-sff"

12

city water in a day in August, all together they would be consuming
about 10 quarts of solid plant and animal substance — enough to make
a meal for about forty people.

One does not think of the lake as an area of luxuriant vegetation,
teeming with animal life, but rather as a barren waste of water. How-
ever, if one's vision for small objects were only better, he would see as
he passes over the water in a boat, thousands of small animals and plants
such as are shown in Figs. 12-18 together with about fifty other forms of
protozoa, wheel animal-
cules, crustaceans, insects,
and small fish. Most of
these spend their entire
existence freely floating or
freely swimming. With
the exception of the fish
and insects they consti-
tute the plankton which is
the basis of the food of the
millions of pounds of fish
taken from Lake Michigan
every year.

From the standpoint
of our economic interests,
the limnetic formation
is of great importance.
It deserves comment also
because of its scientific
interest, and the aes-
thetic value of the vari-
ous forms of which it is
composed.

a) Its composition (85, 86, 87, 88, 89). — The minutest animals of
this formation are the protozoa. About thirteen species have been found
to inhabit the open waters of the lake. Of these the sun animalcule
{Actinophrys sol) (Fig. 12) and the shelled protozoan {Difflugia globu-
losa) (Fig. 14) are easiest to recognize. Nine of the thirteen common
species are mixotrophic in their nutrition (i.e., contain chlorophyll and
manufacture their own food) (Fig. 13) and share with the algae and
diatoms the important function of furnishing food for the rotifers (wheel
animalcules) and the crustaceans.

Fig. 12. — A sun animalcule (Actinophrys sol
Ehrbg.); 330 times natural size (after Leidy).

Fig. 13. — Protozoan (Peridinium tabulatum
Ehrbg.); 400 times natural size (after Kent).

Fig. 14. — A shelled protozoan (Difflugia glohu-
losa Duj.); 130 times natural size (after Leidy).

7 6

COMMUNITIES OF LARGE LAKES

About a dozen species of crustaceans are common in the lake. They
feed chiefly on the protozoa, diatoms, desmids, and possibly the rotifers
(85). Such crustaceans constitute almost the sole food of young fishes and
are the first food of the young whitefishes (79). They are divided into
copepods and Cladocera (and ostracods, rare). This division of the
crustaceans is known as the Entomostraca. The smallest and most

Representative Crustaceans and Rotifers of the Limnetic Community of

Lake Michigan

Fig. 15. — A common copepod (Cyclops bicuspidatus); 25 times natural size
(after Forbes).

Fig. 16. — A cladoceran (Bosmina); enlarged (from Forbes after Gerstaecker) .
Fig. 17. — A cladoceran (Daphne hyalina galeala); enlarged as indicated (after
Smith).

Fig. 18. — A pelagic rotifer (Notops pelagicus Jen.); 180 times natural size (after
Jennings).

Fig. 19. — The same, side view.

abundant of the Entomostraca of the lake is only 1 . 1 mm. in length and
is slender and colorless. It is the slender Cyclops bicuspidatus, shown
in Fig. 15.

The commonest Cladocera of the lake are Bosmina (Fig. 16), Daphne
retrocurva, and Daphne hyalina (Fig. 17). One other small species
(Leptodora hyalina) belonging to this group is a very interesting creature.

SHALLOW WATER COMMUNITIES 77

"When in its native element it is almost perfectly transparent and
consequently invisible — a true microscopic ghost" (Forbes, 89).

The wheel animalcules are as a rule larger than the protozoa and are
of a much higher structural organization, capable of making more
complex movements. About thirteen species of these may be found in
the waters of the lake in midsummer. Notops pygmaeus Calm, (see
Figs. 18-19) is a characteristic member of the group.

In addition to these forms there are also worms, such as round worms,
planarians, leeches, etc., found in the limnetic formation either inciden-
tally or habitually.

None of the adult fishes of the lake belong strictly to the limnetic
formation. Fishes such as the whitefish, lake herring, and lake trout
are sometimes found in the open w r ater, and the young of some lake
fishes may belong there strictly (90).

b) Characters. — Specialists in the various groups of animals might be
able to pick out some structural characters which would distinguish
the forms of such open-water situations from the forms living in among
the vegetation or on the bottoms of this or smaller lakes. The only
striking structural character is the transparent or translucent color of
most of the forms.

A large number, if not all, of the limnetic crustaceans are in deep
water during the day and come to the surface at night. The behavior
of the rotifers is somewhat different. Jennings (87) says: "During
the day the limnetic rotifers are found in much greater numbers near
the surface than near the bottom, reversing the condition commonly
observed for the crustaceans. At night the distribution seems not to be
materially changed. The immense numbers of crustaceans obscure the
rotifers; but there was no greater number of rotifers near the bottom
in the few towings made at night than in the day time."

The most striking characteristic of the limnetic formation is that it is
independent of bottom and in its reactions is indifferent to the bottom.
Jennings (44) states that pelagic forms have a more simple type of
behavior than the attached and bottom forms.

2. BOTTOM COMMUNITIES

Forms inhabiting the bottom of lakes and also of the sea in a general
way bear the same relation to the water that the terrestrial animals do
to the surface of the land. Usually they do not leave it to rise to any
considerable height above the bottom. The fishes of lakes correspond
to the birds of the land.

78 COMMUNITIES OF LARGE LAKES

Other relations are, however, different. As has been stated, there
are no truly rooted plants in the bottom of Lake Michigan. Those
attached to the bottom are not rooted in the way that land plants are.
The things which land plants get from the soil are supplied to the aquatic
plants by the water itself. The same is true of the bottom animals;
food is floating in the water in quantities and can accordingly be secured
without effort, and some animals have the form of plants and simply
depend upon the food which may be brought within reach by accident.

Classification of bottom formations: Bottom formations are de-
termined by depth (and associated phenomena) and bottom. Bottom
is of greatest importance in shallow water (less than 8 meters). Its
importance is inversely proportional to depth.

Within the zone of wave-action conditions are somewhat different
than below it. Here the kind of animals is determined by (i) strength
of wave-action, (2) erosion and kind of material eroded, and (3) deposi-
tion, and animal communities may be classified as those of (1) eroding
— rocky or stony — shores, (2) depositing or sandy shores, and (3) pro-
tected situations.

a) Eroding rocky shore sub-formation (80, 81, 82, 83, 84) (Stations
1a, 2; Table XV). — There are a considerable number of rock outcrops in
the bottom inside the 8-meter (26 ft.) line, between Gross Point and the
mouth of the Calumet River at South Chicago (61). As we shall see
later, these are of great importance to the animals of the lake. However,
the communities of such situations are known to us only through the
study of the very shallow water in the vicinity of Glencoe. Here, attached
to the rocks by their silk, are caddis- worms (Hydro psyche). (Mr. W. J.
Saunders has given me specimens of Pamidae (Psephenus) and stone-fly
nymphs (Perla) taken from Lake Ontario at Kingston, Ontario.) All
these ordinarily live in swift streams. Under the stones and among
the algae attached to them are amphipods (Hyalella knickerbockeri)
and May-fly nymphs (Ephemeridae) , but so far as we have been able to
record these are the only forms common here. The animals avoid the
waves by creeping under stones or are attached to withstand wave-
action. The lake trout (Fig. 20) is known to breed on the rocks off
Lincoln Park. These rocks are then of considerable importance to the
fish. Some species of small fish may be common here, but they have
not been studied.

b) Sandy depositing shore sub-formation, 0-8 meters (26 ft.), shifting
sand bottom (Station 3; Table XII). — On the open shore inside of 1 . 5
meters (5 ft.) of water we have found nothing on the bottom. From this

SHALLOW WATER COMMUNITIES

79

depth to 4 meters (13 ft.) Sphaerium vermontanum, which occurs rarely
in Hickory Creek also, and midge larvae (a red and a white species)
appear characteristic. A number of species of small fish such as the
blunt-nosed minnow, the straw-colored minnow, and shiners are likely
to be found in from 4-8 meters (13-26 ft.) of water. An occasional
Lymnaea woodruffi is found at this depth.

'

A

^

JS5

Hfete

^"*si| ,

^^saniaSSfc^,

■'- """ "'■' 'V

21

Representative Fishes Belonging Mainly to the Transition Belt of
Lake Michigan (25-54 m.)

Fig. 20. — Great Lakes trout {Cristiwmer namaycush); length 3 feet (after Jordan
and Evermann).

Fig. 21. — The long- jaw whitefish (Argyrosomus prognathiis); length 15 inches;
from the depth of 74 meters (after Smith).

c) Communities of protected situations (Table X). — Near Chicago,
bays and inlets are rare. Doubtless the mouths of some of the larger
rivers, before they were modified for navigation, were of this character.
Such places have been studied in Lake Superior (80, 83) and the Grand
Traverse Bay region. Out of 21 species recorded here, 16 are definitely

80 COMMUNITIES OF LARGE LAKES

recorded below 9 meters and not on the open shores. All are found in
small lakes and sluggish streams.

d) Lower shore formation (8-25 meters) (Station 3; Tables XI, XIII,
XV). — The belt immediately below the shore belt is characterized by
wave-action sufficient to move only the finest material. Its lower limit
is the limit of wave-action; the beginning of light diminution; the lower
limit of daily fluctuation in temperature; and the lower limit for most
of the species of Mollusca (75, appendix). Practically all the forms that
have been recorded here are inhabitants of still, shallow water also.
Notable among these are the common still-water amphipod Eucrangonyx
gracilis, the little bivalve Sphaerium striatinum, and several species of
Amnicola and Valvata which, together with Lymnaea woodruffi, are more
characteristic of Lake Michigan than of shallow waters. While a large
number of Mollusca are recorded from the lake above 25 meters only the
Sphaeridae are found below this limit. Small annelids, midge larvae,
and leeches are very abundant north of Gary, Ind., in 1 1 meters of water.

This belt is the principal breeding-ground of the whitefish. The
eggs are deposited on the bottom and left unguarded. It appears that
the young fish stay in the shallow waters for a considerable time. Wher-
ever the bottom is firm the lake trout breeds also. Nearly all the fish
traps are set in the upper edge of this belt and in the lower boundary of
the one above.

e) Belt of overlapping: upper deep-water belt (25-54 meters) (Tables
XIV, XV). — This belt is characterized as below wave-action, below
daily fluctuations of temperature, with seasonal fluctuations not exceed-
ing 3 C. It is intermediate between the belt above and the deep belt,
and is the characteristic feeding-ground of the whitefish and the regular
home of the long-jaw (Argyrosomus prognathus, Fig. 21). On the other
hand, it is the upper limit for some of the deeper-water forms, such as the
well-known My sis relicta and Pontoporeia hoyi (Figs. 22, 23), the deep-
water crustaceans which are the chief food of the whitefish.

/) Deep-water formation (54 meters to bottom) (Table XV). — This
belt is characterized by weak or no light and by seasonal changes in
temperature less than 1 degree. Below 115 meters there are no light
and no seasonal changes, and the temperature is 4 C. throughout the
year. Off Racine in 82 meters (265 ft.) the bottom is of reddish-brown
sandy mud (82); in 95-125 meters (311-410 ft.) dark-colored impalpable
mud, depressions with decaying leaves (82 a). In the Grand Traverse
Bay region, Milner found decaying sawdust in 183 meters (600 ft.) (81).
Except for unimportant variation in bottom, conditions are practically
uniform throughout. Milner (81) states that the invertebrates are

SUMMARY

81

abundant and evenly distributed throughout the deep-water belt. The
principal invertebrates are Pontoporeia hoyi, My sis relicta, water-mites,
midge larvae, and a species of Pisidium.

The fish, however, show some noteworthy peculiarities of distribution.
The lake trout rarely leaves this belt, except during the breeding season.
The blackfin (Argyrosomus nigripinnis) is below 70 meters, except in
December, when it has been recorded in 60 meters. Hoy's whitefish

Representative Crustaceans of the Deep-Water Community of
Lake Michigan

Fig. 22. — A schizopod (Mysis relicta); enlarged as indicated (after Smith).
Fig. 23. — An amphipod {Pontoporeia hoyi) (after Smith).

{Argyrosomus hoyi) is rare, and Triglopsis ihompsoni has not been
recorded above 115 meters; all accordingly live under uniform condi-
tions — no day, no night, no seasons.

III. Summary

The available data on the conditions and life in the lake are of such
a nature as to justify few conclusions of weight. We find only hints
here and there which may be useful to those who shall investigate the
lake in the future.

1. Bottom forms are the most abundant on the open shores which
are rocky, and which form good substrata for the attachment of algae
and the holdfast organs of animals.

82 COMMUNITIES OF LARGE LAKES

2. The sand-depositing shores are without animals, at least to a depth
of i . 5 meter, and life is scanty to 8 meters, on account of the shifting
character of the bottom.

3. Animals are abundant in protected bays; the species inhabiting
these situations are commonly found in sluggish streams and small
lakes, and a few of them have been recorded below 8 meters also, which
is relatively quiet water.

4. The animals of the upper shore belt, 0-8 meters, are found also
in swift streams.

5. The animals of the lower shore and upper deep-water zone are
below effective wave-action and are those found in still waters.

6. The animals of the deep-water zone are not found outside of deep
lakes, and cannot be compared with any others of our Chicago area.

7. We have, then: swift-water animals in the upper belt, still-water
animals in the middle belt, and deep-water animals in the lowest.

8. The fish are migratory and deserve special comment.

DISTRIBUTION OF WHITEFISH AND DEEP-WATER FISH IN LAKE MICHIGAN (75)

Argyrosomus artedi, the lake herring, is near the surface.

Coregonus clupeiformis, the whitefish, lives most commonly between 21 and

36 meters; it spawns in water between 3 and 28 meters, most commonly

between 15 and 19 meters. It makes migrations into the 9-meter belt

in summer, supposedly on account of bad aeration; has disappeared

where breeding-grounds have been destroyed.
Argyrosomus prognathus, the long-jaw, is found mainly in from 36-66 meters.
Argyrosomus nigripinnis, the blackfin, is found in from 70-80 meters, coming

up to 60 in December.
Argyrosomus hoyi, Hoy's whitefish, is usually recorded below 115 meters.
Triglopsis thompsoni is confined below 115 meters.
Cristivomer namaycush, the lake trout, is confined below 25 meters, except

during the breeding season. It breeds between 2 and 25 meters on rock

or other hard bottom.
Lota maculosa, the lawyer, appears to be distributed throughout, but no

account is to be found regarding its movements or their causes.

An interesting truth is illustrated by the species of whitefishes
(Argyrosomus and Coregonus). If a group is to be successful and become
extensive in its distribution, it must so differentiate in habits as to bring
the different races out of competition with each other. We usually
find that different species which are closely related have different habitats.
Here we have these species of fish arranged one above the other. The
separation in such cases is usually horizontal.

ANIMALS OF LARGE LAKES

83

Animals Recorded from Lake Michigan 1
list I

Common Entomostraca
Copepods: Cyclops leuckarti Claus, C. bicuspidatus Claus, C. prasinus Fischer,
Epischura lacustris Forbes, Diaptomus ashlandi Marsh, D. oregonensis Lil.; Clado-
cerans : Daphne hyalina Ley., and D. retrocurva Forbes.

TABLE X

Animals occurring in protected situations (bays, harbors, etc.) in Lake Superior
in from 0-2 meters of water, and known also to occur in Lake Michigan where habitats
are not recorded:

Common Name

Scientific Name

Literature

Mussel

AnodontcL grand is Say .

(75, S3, 9i)
(75,83,91)
(75, S3, 9i)
(75, S3, 9i)

Mussel

Anodonta marginata Say

Snail

Amnicola lustrica Pils

Snail

Valvata tricar inata Say

TABLE XI

Animals of the lower shore belt. Those definitely recorded from 8-15 meters of
water are marked * and **, the latter indicating that the records are original from
11 meters of water north of Gary, Ind. (Station 3); f indicates that the animals
are recorded from protected bays in 0-2 meters of water (Lake Superior), and If
that they occur in inland waters, especially ponds:

Common Name

Scientific Name

Literature

tif Snail

tif Snail

Lymnaea stagnalis Linn

Planorbis bicarinatus Say

(75, S3, 9i)
(75, S3, 91)
(75,83,91)
(9i)
(91)

tif Snail

Planorbis exacutus Say

tH**Snail

Amnicola limosa Say

t1f**Snail

Amnicola limosa porata Say

t1f**Snail

Amnicola emarginata Kiister

(91)

t1f**Snail

A mnicola lustrica Pils

(9i)

**Snail

Valvata bicar inata perdepressa Walk

Valvata sincera Say

tif Snail

(9i)

(75, S3)
(S3, 9i)
(9i)

(75,83,91)
(75,83,91)

(75, 9i)
(80)

t **Bivalve

Pisidium idahoense Roper

t1f**Bivalve

Pisidium scutellatum Sterki

t1f**Bivalve

Pisidium compressum Prime . .

tif* Bivalve

Pisidium variabile Prime.. .

tif* Bivalve

Pisidium ventricosum Prime

tif* Bivalve

Pisidium punctaium Sterki ....

t1f**Bivalve

Sphaerium striatinum Lamarck

Calyculina transversa Say

t1f**Bivalve

(9i)

i
(91a)

If* Midge larva

Mctriocnemis sp

If* Leech

Glossiphonia stagnalis Linn

1f**Worm

Limnodrilus claparedianus Ratzel

t See citation 98.

1 The numbers in parentheses in the column headed
ences in the Bibliography at the end of the book.

'Literature" refer to refer-

84

COMMUNITIES OF LARGE LAKES

TABLE XII

Animals on depositing shores in from 0-8 meters of water, * indicating that
records are original.

Common Name

Scientific Name

Literature

Chironomid larvae

*Bivalve

Sphaerium vermontanum Prime (characteris-
tic)

Metriocnemus sp

♦Snail

Lymnaea woodruffi Baker (rarely)

Catostomus calostomus Fors

Long-nosed sucker

(81, 84)
(81, 84)

Catostomus commersonii Lac

Calostomus nigricans LeS

(81, 84)

Moxostoma aureolum LeS

(81, 84)
(81)

Percopsis guliaius Ag

Notropis hudsonius DeW. Clin

(84)

(84)
(84)

*Shiner. .

Nolropis atherinoides Raf

*Blunt-nosed minnow

Top minnow

Pimephales notatus Raf

Fundulus diaphanus menona J. and C

Boleosoma nigrum Raf

Microperca punctulata Put

(84)
(84)

(84)

(84)

Lake herring

Argyrosomus artedi LeS

Eupomotis gibbosus Linn

(75, 84)

(81)

Bluegill

Lepomis pallidas Mitch

(81)

(81)

Eel

(81, 84)

TABLE XIII

Animals occurring in from 15-25 meters of water:

Common Name

Scientific Name

Literature

Snail. . . .
Polyzoan
Snail. . . ,
Snail. . . ,
Leech. . .
Larvae. .
Rotifer. .
Rotifer. .

Amnicola walker i Pils. . . .

Plumalella sp

Pleuroceridae

Lymnaea sp

Clepsine sp

Neuropteroid insects. . . .
Rotifer elongatus Weber . .
Dinocharis tetractis Ehrbg

(75, *3)
(81, 82)
(81, 82)
(81,82)
(81,82)
(81, 82)
(75)
(75)

TABLE XIV

Animals occurring in from 25-54 meters of water:

Common Name

Scientific Name

Literature

Pisidium sp

(82)

Paludicella ehrenbergii van Ben

(75)

Frr.dp.ri.r.ella sultana Blum. . . . •.

(75)

ANIMALS OF LARGE LAKES

85

TABLE XV

Showing the recorded distribution of animals occurring in several of the vertical
belts of Lake Michigan. The star indicates that the animal is present at the
depth indicated at the head of the column in which the star occurs. B indicates
that it breeds, and F that it feeds, at the indicated levels. The numbers in the
column headed "Literature" refer to the Bibliography at the end of the book.
The lower depth limit of many of the fishes listed is somewhat uncertain, as
Milner does not indicate their exact distribution inside of 35 meters, but implies
that they may occur at the depths indicated in the table. Other records bear
out Milner's implications.

Common Name

Sturgeon

Crayfish

Crayfish

Long-nosed gar

Lake catfish

Croaker

Perch

Wall-eyed pike

Large-mouthed black

bass

Small-mouthed black

bass

Northern moon-eye . .

Toothed herring

Tadpole cat

Carp

Pike

Brook silverside

Stickleback

Whitefish

Rock bass

Amphipod

Snail

Long-jaw

Lawyer

Lake trout

Hoy's whitefish

Amphipod

Schizopod

Blackfin

Small cottoid

Scientific Name

Acipenser rubicundus LeS.
Cambarus propinquus Gir .
Cambarus virilis Hag. . .
Lepisosteus osseus Linn.
Ameiurus lacustris Wal.
A plodinolus grunniens

Raf

Perca flavescens Mitch..
Stizostedion vitreum Mitch.

Micropterus salmoides Lac

Micropterus dolomieu Lac

Hiodon alosoides Raf

Hiodon tergisus LeS

Schilbeodes gyrinus Mitch

Carpiodes sp

Esox lucius Linn

Labidesthes sicculus Cope
Eucalia inconstans Kirt. . .
Coregonus clupeiformis

Mitch

Ambloplitcs rupestris Raf.
Eucrangonyx gracilis

Smith

Lymnaea lanceata Gld. .
Argyrosomus prognathic

Smith

Lota maculosa LeS

Crislivomer namaycush

Wal

Argyrosomus hoyi Gill

(MSS) . m ; .......

Ponloporeia hoyi Smith. .
My sis relicta Loven. . .
A rgyrosomus nigripin n is

Gill

Triglopsis thompsoni Gir

Depth in Meters

Literature

(75, 81)
(7S.P-IS)
(75,P-i5)
(81, 84)
(81, 84)

(84)
(81, 84)
(81)

(81)

(81, 84)
(81, 84)
(81,84)
(81)
(81, 84)
(81)
(75,- 81)

(75- 81)
(81)

(80)
(75, 80)

(75)
(75,8i)

(75, 81)

(75, 81)
(82, 75)
(82, 75)

(75, 81)
(75, 81)

CHAPTER VI

ANIMAL COMMUNITIES OF STREAMS

I. Introduction

The conditions in streams from headwaters to mouth have many
features in common with lakes, like Lake Michigan. It is therefore
appropriate that they follow the discussion of such a lake. The streams
belong to two drainage systems — the Mississippi and the Saint Lawrence.
All are tributary either to Lake Michigan or to the Illinois River. The
principal tributaries of the lake near Chicago are the Chicago River, the
Calumet River, Trail Creek, the Galien River, the St. Joseph River,
and the Black River. The principal tributaries of the Illinois River,
with which we are concerned, are the Fox River, the DesPlaines River,
the DuPage River, the Kankakee River, Salt Creek (111.), Hickory Creek.

The factors of greatest importance in governing the distribution of
animals in streams are current and kind of bottom. They influence
carbon dioxide, light, oxygen content, vegetation, etc.

These factors are controlled by age (physiographic), length of stream,
and elevation of source above the mouth, all of which are physiographic.
The typical stream begins as a gully and works its way into the land
(Fig. 68, p. 112). The importance of some of the factors is greater in
some stream stages than in others. For example, in the younger stages
(a) material eroded, (b) relation to ground water, and (c) slope of stream
bed play a more important role than they do in later stages.

II. Communities of Streams

I. CLASSIFICATION

The classification of stream communities is based upon physio-
graphic history and physiographic conditions. In the early stages of
stream development there are two types to be distinguished: (a) the
communities of intermittent streams, and (b) spring-fed streams. As
soon as the intermittent stream cuts below the ground-water level,
it becomes much like the spring-fed stream. Permanent streams are
divided into brooks, swift and moderate, and rivers, sluggish and moder-
ate, with communities named accordingly. We undertake a discussion,
first, of the history of the communities of streams developing in materials

86

INTERMITTENT STREAMS

87

easily weathered and eroded, containing bowlders, gravel, and occasional
strata of hard rock.

2. THE INTERMITTENT STREAM COMMUNITIES

(Stations 4-8; Tables XVII, XVIII)
There are two types of these — intermittent rapids and pool
communities.

An Intermittent Stream

Fig. 24.— The young stream at Glencoe in spring at high water, showing the
leaf-barren trees.

Fig. 25. — The same in summer, showing the stream entirely dry.

a) Temporary rapids consocies (Figs. 24, 25). — Small gullies in
which water runs only when it is raining do not have any aquatic
residents. As soon as such a gully has cut a channel deep enough to
stand below ground- water level during a few days or weeks of the rainy
season, aquatic insects make their appearance. The species which is
usually found in the smallest trickle of water is the larva of the black fly,
Simulium (Figs. 27-32). As the stream grows a little larger, and per-
haps even at such a young stage also, we sometimes find the nymphs

88

ANIMAL COMMUNITIES OF STREAMS

of May-flies. Such streams have, however, no permanent aquatic resi-
dents. These aquatic forms are not aquatic during their entire lives.
They require water only during their early stages. If the water is
running at the time the female is ready to deposit eggs and if she is
properly stimulated by the conditions, she deposits them without regard
to future conditions. If the wet weather continues long enough, the
larvae will mature and the other adults will appear, otherwise they die.
This type of animals continues after the stream becomes large enough

Stream Communities

Fig. 26. — The pupal case of one of the caddis-worms (RhyacophUa) from the
rapids of the temporary stream at Glencoe; enlarged as indicated (original).

Fig. 27. — The larva of the black fly (Simulium); about 15 times natural size
(after Lugger) .

Fig. 28. — Pupa of the same (after Lugger).

Fig. 29. — Pupa of the same in the pupal case (original).

to have permanent pools. At such a stage the number of species is
increased, but no two collections are alike (see Table XVII). Clinging
to the upper surface of the stones are black-fly larvae, caddis-worms
(Rhyacophilidae) (Fig. 26); under stones, May-fly nymphs, those col-
lected as different times often belonging to different species. On some
occasions there are great numbers of unidentifiable dipterous larvae
and caddis-worms without gills or cases. Such a stream may possess
any or all of these on one occasion, and none or only a few of them on
another.

INTERMITTENT STREAMS

Fig. 30. — The eggs of the black fly, about 15 times natural size (from Williston
after Lugger). Fig. 31. — Side view of the adult fly (from Williston after Lugger).
Fig. 32. — The same from above (from Williston after Lugger).

90 ANIMAL COMMUNITIES OF STREAMS

b) Temporary pool consocies. — As a young stream grows deeper it
often reaches some depression or marsh at its headwaters of which it
forms the outlet in the early spring. It is now permanent for a longer
period each season of normal rainfall, and small pools usually alternate
with the rapids just described. In these pools aquatic insects, crus-
taceans, and snails which belong primarily to stagnant ponds make
their appearance. The first resident species are the crayfishes. They
are found in the pools in the early spring when the water is high. The
drying of the stream calls forth behavior suited to the conditions,
and in summer their burrows are common in the stream bed. They
come out at night and are preyed upon by raccoons, the tracks of which
are commonly seen.

c) The homed dace, or permanent pool communities. — The first per-
manent parts are permanent pools. In these, conditions such as current,
sediment, oxygen content, etc., are intermittent or spasmodic. The
current in the rapids is distinctly spasmodic and conditions in these
rapids are similar to those in the stream before even temporary pools
were developed. Streams with permanent pools are represented in the
Chicago region by many which enter the lake where high bluffs are
present. County Line Creek (Figs. 24, 25) has been studied as an illus-
tration of this type (Table XVII).

The larger pools possess a practically permanent fauna. The char-
acteristic forms are the crayfishes (Cambarus virilis and propinquus).
The young are to be found in the pools at all seasons of the year. Water-
striders, back-swimmers, and water-boatmen are common. Occasionally
one finds dragon-fly nymphs (Aeshna constricta and Cordulegaster obli-
quus), dytiscid beetles (Hydroporus and Agabus), crane-fly larvae, the
brook amphipod (Gammarus fasciatus), and the brook mores of the sow-
bug {Asellus communis) (Fig. 55, p. 98). These are common among the
lodged leaves. They move against water current.

The species of fish (Table XVIII) which is most commonly found
in the smallest streams (92) and nearest the headwaters of the larger
streams is the horned dace or creek chub (Semotilus atromaculatus) (Figs.
33, 34). It possesses certain noteworthy physiological characters. Like
many other species of fish, it goes farthest upstream for breeding (50).
Its nest is made of pebbles. Often after the breeding season is over, and
the adults have gone downstream, the water lowers so that young fishes
are left in large numbers in small drying pools. Here they swim about,
with their mouths at the top of the water, which is constantly being
stirred up by the many tails, and which often contains much blackened,

INTERMITTENT STREAMS

91

oxygen-consuming excreta and decaying plant materials. This would
cause death to less hardy fishes. Allee (53) found very little oxygen in
the waters of such pools. As it is, the pools often dry up, and the fish
die. The second fish to enter a small stream appears to have many of
the characters of the first. It is usually the red-bellied dace (Chrosomus
erythrogaster), which breeds on sandy or gravelly bottom (93) but toler-
ates standing water, being found also in some of the stagnant ponds at the
south end of Lake Michigan. In some streams, the black-nosed dace
(Rhinichthys atronasus) (Fig. 35) is second from the source. These fishes
go against the current, but avoid the places where it is most violent.

Breeding Habits of a Pioneer Stream Fish

Fig. 33. — Showing, in longitudinal section, the nest of a horned dace (Semotilus
atromaculatus) , with male and female fish in the nest. The stream flows in the direc-
tion indicated by the arrow at the upper left-hand corner of the picture; | natural
size (after Reighard) .

Fig. 34. — Male and female horned dace during the spawning act. Each time
the male clasps the female she deposits 25 to 50 eggs in the nest. Note pearl organs on
the head of the male (after Reighard) .

This one also breeds on gravel bottom, and can withstand the stagnant
conditions of the summer pools.

As the stream lowers its bed, this type of formation passes gradually
into a later one. The beginning of the succeeding formation is heralded
by the coming of the Johnny darter (Boleosoma nigrum), the common
sucker (Catostomus commersonii) (Fig. 36), and the blunt-nosed minnow
(Pimephales notatus) (Fig. 37) (79).

d) Characters of the communities. — The intermittent-stream com-
munities are made up of animals which are dependent upon water
during only a part of their lives and which possess a means of attach-
ment and move against current (94) (positive rheotaxis). The pool
communities are made up of animals tolerating great extremes of

02

ANIMAL COMMUNITIES OF STREAMS

conditions and being also positively rheotactic. The fish are able to
meet the current and to withstand the conditions of the stagnant pools.
The crayfishes live in the water in the spring and burrow in the

*

35

37
Pioneer Stream Fishes
Fig. 35. — Black-nosed dace {Rhinichthys atronasus) (from Forbes and Richardson).
Fig. 36. — Common sucker (Catostomus commersonii); length 18 in. (from Meek
and Hildebrand after Forbes and Richardson).

Fig. 37. — Blunt-nosed minnow (Pimephales notatus); length 2 to 3! in. (from
Forbes and Richardson).

dry weather; adults of the aquatic insects creep into moist places
when the stream dries. Allee (53) has found that isopods are positively
rheotactic and that they can be acclimated to extreme conditions.

SWIFT STREAMS 93

3. SPRING BROOK COMMUNITIES

(Stations 10 and 11; Table XIX)

In glaciated areas many of the streams are fed by springs which
have not been produced by erosion, but are the result of porous and
impervious layers of till arranged as in regions possessing artesian wells.
The presence or absence and numbers of animals in a spring depend
largely upon the chemical content of its water. Spring waters commonly
have insufficient oxygen to support animals and at the same time may
contain sufficient nitrogen and carbon dioxide to be detrimental if not
fatal to animals. The mineral matter in solution may be large in
quantity and in some cases poisonous also. As the water flows away
from the spring it becomes aerated and diluted with surface water so
that the animals of the spring brook can live in it. Spring consocies differ
in different springs because of variations in the character of the water.

In an area where there are springs, they are usually numerous.
The little brooks unite to form larger streams. Typically, such streams
may not be larger than intermittent streams, but a nearly constant
flow at all times of the year is one of the characteristic conditions.
Pools and riffles are not so well defined, but contain some small fishes.
The watercress grows abundantly at the sides of the stream and affords
a lodging-place for aquatic animals not furnished so abundantly by
young streams of other types. The water is colder in summer and
warmer in winter than in other streams.

Spring brook associations. — Among the watercress are the amphipods
(Gammarus fasciatus), the larvae of Simulium attached to the leaves,
beetles, dragon-fly nymphs, and young crayfishes. Here are also found
occasional snails (Physa gyrina). The species of the cress association
are nearly all found under stones or on stones in the riffles. On the
stones are Simulium larvae and Hydropsyche (95), the net-building
caddis-worm (Figs. 39, 40, p. 96). Under the stones are the nymphs of
the May-fly (Baetis and Heptagenia), the larvae of flies and midges
(Chironomus, Dixa, and T any pus), the brook beetles (Elmis fastiditus)
(Fig. 47, p. 98), and occasional amphipods and crayfishes.

4. THE SWIET- STREAM COMMUNITIES

As the spring brooks and the intermittent streams continue to
erode their beds, they increase the extent of their drainage systems and
become larger streams. Springs tend to disappear in connection with
the spring brook and the intermittent stream reaches the ground- water
level and becomes permanent. The two sets of conditions converge

94 ANIMAL COMMUNITIES OF STREAMS

toward the larger swift stream (Fig. 38). While the conditions in these
are like those of the spring brook, the watercress is absent and there are
few rooted plants. Pools and riffles are well developed and the flow of
water is constant, but fluctuates in volume. These streams differ in
size, but the formation mores are practically the same, although larger
species commonly inhabit the larger stream.

a) Pelagic sub-formation is very poorly developed in the smaller
streams and will be discussed in connection with sluggish streams.

Fig. 38. — The permanent swift stream showing the stones in the rapids, and the
stiller places below (New Lenox, 111., Gaugars Station) (original).

b) Hydropsyche or rapids formations (Stations 14, 15, 17, 19, 20, 21;
Tables XX, XXI, XXII). — These are usually due to the presence of
coarse material or an outcrop of rock. They are typical in streams with
large bowlders and stones of all sizes. Here current is probably the
controlling factor. In these streams, we find the best expression of the
riffle formation, which we have seen is poorly developed in the smaller
streams. This formation includes three ecologically equivalent modes of
life, each meeting the current in a different way. These are (i) clinging

SWIFT STREAMS 95

to stones in the current, (ii) avoiding the current by creeping under
stones, (iii) self-maintenance by strong swimming powers.

Upper surface of stones (stratum 1) : Here again we find the black-fly
larvae, particularly in the smaller streams. They are provided at the
posterior end of the body with a sucker surrounded with hooks (Figs.
27-32). The salivary glands are, as is common in insects, modified into
silk glands and the silk is of such a nature that when it is brought into
contact with a stone it adheres. The animals are usually found attached
to the rock by the sucker, with the head downstream. The fans are
extended and serve to catch diatoms and other floating algae. If for
any reason the sucker gives way, the animal starts to float downstream.
If the mouth can be brought into contact with a stone, the silk is exuded
and the animal is held until it can make the sucker fast again. The
pupae of this fly are also attached to the stones. They are surrounded
with a cocoon. We have removed them from the stream and have
found that they cannot make this cocoon in the absence of the current,
but make a shapeless tangle instead. The adults deposit their eggs at the
sides of the streams (96).

On the tops of stones caddis- worms (Hydropsyche sp.) usually have
cases made of pebbles stuck together with silk (Figs. 39, 40). They also
have a net for catching floating food. The net faces the current (usually
upstream) (Fig. 40). The river snail (Goniobasis livescens) (Fig. 54) is
common on the upper surfaces of the larger rocks and is distinguished
by a strong adhesive foot. These snails are usually headed upstream.
When placed in a long piece of eave-trough into which the tap water was
running at one end, they nearly all made their way to the upper end
within a short time. They are ecologically equivalent to the caddis-worms
and the black-fly larvae.

Among the stones (stratum 2) : Of the animals living among stones,
the darters are most important. Of these the banded darter (Etheostoma
zonale) (Fig. 44), the fan-tailed darter (E. flabellare), and the rainbow
darter (E. coeruleum) (97) (Fig. 45) live among and under the stones or
in the algae which cover the rocks (especially the fan tail). With them
are sometimes found the Johnny darter (Boleosoma nigrum), the black-
sided darter (Hadropterus as pro) (Fig. 46), and the small bullhead or
stonecat (Schilbeodes exilis). These fish are all positively rheo tactic.
They apparently orient because of unequal pressure on the two sides of
the body when it is not parallel with the direction of the current.

Under the stones (stratum 3): There are many more forms living
under and among the stones than on the tops of them. Here are the

o6

ANIMAL COMMUNITIES OF STREAMS

May-fly nymphs, the flattened Heptageninae, and the very awkward
damselfly nymph, Argia, evidently succeeding well together. This
fact makes the value of the flattening as an adaptation appear nil.
There are also the larvae of midges (Chironomus sp.) (98) and of horse-
flies (Tab anus) (Figs. 51, 52). The adults of the latter deposit their
eggs in great masses on the tops of the stones which protrude from the
water. The stone-fly nymphs, similar to the Heptageninae May-fly

Representative Aquatic Insects of a Rapids Community

Fig. 39. — The net of the brook caddis- worm {Hydro psyche) seen from the front.
Drawn from a specimen which made its case against the side of an aquarium (original).

Fig. 40. — The same in its case with the net adjoining the opening which faces
upstream (original).

Fig. 41. — The larva of a caddis-fly (Helico psyche) with a case made from pebbles,
in the form of a spiral; 2\ times natural size (original).

Figs. 42, 43. — The water-penny larva of the brook beetle (Parnidae) seen from
above and below (43); 2§ times natural size (original).

nymphs in form and appearance, are found here also. Perhaps the
most bizarre of all are the water-pennies. These are round flat objects
adhering to the under sides of stones, and not looking like animals at
all. They are the larvae of a parnid beetle (Psephenus). Figs. 42 and
43 show two views of a larva. The old larval back becomes the cover
for the pupa. The adults live under the stones also and their general
appearance is like that of the parnid in Fig. 47. Sessile or attached
animals are common in the brooks, but their numbers vary greatly from

SWIFT STREAMS

97

year to year. On one occasion the surface of the rocks and stones in
Thorn Creek was almost covered with sponge, and while some sponge is
always to be found, we have not seen it so abundant again. Polyzoa

Representative Fishes of a Rapids Community
Fig. 44. — The banded darter {Etheostoma zonale); length 2 in. (from Forbes).
Fig. 45. — The rainbow darter (Etheostoma coeruleum); length 2 in. (from Forbes).
Fig. 46. — Black-sided darter (Hadropterns aspro); length 3-4 in. (from Forbes).

are usually present under the stones. Such animals depend upon foods
in solution and small floating plants and animals.

In addition to those rapids which have large rocks, are those in which
the bottom is of coarse sand and gravel, with only a few small stones.

9»

ANIMAL COMMUNITIES OF STREAMS

47

'

50

53

(^

Representative Animals of a Rapids Community

Fig. 47. — An adult brook beetle (Parnidae); twice natural size (original).

Figs. 48-50. — Different views of the nymph and adult of the May-fly (Siphlurus
alter natiis)] 2,2 times natural size (after Needham).

Fig. 51. — The eggs of a tabanid fly taken from a protruding stone; twice
natural size (original). Fig. 52. — Adult fly.

Fig. 53. — A water-strider (Rhagovelia collaris), from the margin of the swift
brook (New Lenox, Gaugars) ; twice natural size.

Fig. 54. — The common river snail (Goniobasis livescens), covered with calcium
carbonate secreted by algae; natural size (original).

Fig. 55. — An intermittent stream sowbug (Asellus communis); twice natural
size (original).

SWIFT STREAMS 99

Here we find the caddis- worm (Helicopsyche) (Fig. 41, p. 96), which has a
spiral case made of sand grains. These are most abundant where some
sand and swift current are both found. There is from time to time some
vegetation in such situations and on it we find the brook damsel-fly
nymph (Calopteryx maculata), the adult of which is the black- winged
damsel-fly.

Characters of the formation: The swift-stream formation has a
striking behavior character, namely, strong positive rheotaxis. Other
physiological characters, such as the toleration of only low temperatures
and high oxygen content, and the necessity for current for the successful
carrying-on of their building operations, are probably common to the
animals. So far as the fishes of the rapids are known, they breed on
coarse gravel bottom or under stones. The mores of the formation are,
then, current resisting and current requiring, dependent upon large
stones or rock bottom for holdfast and building materials.

c) Sandy and gravelly bottom formation {pools) (Stations 15-22;
Tables XVII-XXV). — The pools of streams with characteristic forma-
tions are usually 2 or 3 to 10 feet deep, depending upon the size of the
stream. The bottom is sand or coarse gravel. In these we find condi-
tions very different from those in the rapids. The pools are the home
of the rock bass (Ambloplites rupestris), the small-mouthed black bass
(Micropterus dolomieu), the sunfishes (Lepomis pallidus and megalotis),
and the perch (Perca flavescens), together with a number of interesting
small fishes whose distribution is shown in Tables XXI and XXII

(79> 9 2 )-

With these are also the mussels (91), frequently as many as nine or
ten species, among which are Lampsilis luteola, ventricosa, and liga-
mentina, the little Alasmidonta calceola (Figs. 57, 58), and Anodontoides
ferussacianus (Figs. 59, 60), the last-named being perhaps the most
characteristic of them all. They are often found beneath the roots of
willows along the sides of the pools. Mr. Isely found that mussels
migrate to shallow water during flood time. Mussels are dependent
upon fish for a part of their lives. The young are carried by the adult
until ready to attach to the body of the fish (99). When they leave the
fish they are able to take care of themselves. Burrowing in the gravel
are bloodworms (Chironomus sp.) (95, 98), the burrowing dragon-fly
nymph (Gomphus exilis), a burrowing May-fly (Fig. 64a, p. 107), a caddis-
worm, and occasionally snails, Campeloma (Fig. 61 or 64^) and Pleuro-
cera (Fig. 64^). There are a few plants that grow on the sandy bottom
in such places, and among these one finds the snail {Amnicola limosa),

IOO

ANIMAL COMMUNITIES OF STREAMS

Representatives of the Pool Community

Fig. 56. — A long-legged spider taken from a stone out of water in a stream
(Tetragnatha grallator); twice natural size (original). Fig. 57. — Outside of shell of a
small mussel from Hickory Creek (Alasmidonta calceola); natural size (original).
Fig. 58. — Inside of the same. Fig! 59. — Inside of shell of mussel from Hickory Creek
(Anodontoides ferussacianus, subspecies subcylindraceus Lea); natural size (original).
Fig. 60. — Outside of the same. Fig. 61. — A snail from the still water of Thorn Creek
(Campeloma subsolidum); natural size (original). Fig. 62.: — A snail from the still
water of Hickory Creek (Planorbis bicarinatus) , seen from the left; natural size
(original). Fig. 63. — The same seen from the right.

SANDY BOTTOMED STREAMS 101

May-fly nymphs (Siphlurus) (Figs. 48-50), and hair-worms (Gordius). In
some localities bivalved mollusks (Sphaeridae) and leeches are numerous.

Under primeval conditions beavers are associated with the pool for-
mation. They build dams which contribute to the deepening of the
water of the pools. For a good account of their habits see citation ggb.
An old beaver dam is supposed to have turned the waters of the
DesPlaines out of the Chicago River and down the Chicago outlet.

Characters of the formation : The mores of the pool formation are dis-
tinctly those of partially burying the body just beneath the surface of
the fine gravel and moving against the current. The few animals that
make cases usually use gravel or sand grains. A single caddis-worm
makes its case from small sticks such as commonly lodge in eddies.
Some of the fishes breeding in these situations cover their eggs (50).
Some fishes orient the body and swim upstream as a result of seeing the
bottom apparently move forward below as the fish floats down (94).
They behave the same if put into a trough with a glass bottom and the
trough drawn forward. Some orient also when their bodies rub against
the bottom when floating downstream.

5. the communities of sandy bottomed streams (shifting bottom

sub-formations)
(Stations 22-26; Table XXIV)

We have studied the upper course of the Black River, the upper
course of the Calumet River, and the Deep River, and two or three
tributaries of Lake Michigan near South Haven. The kind of material
eroded is of the greatest importance in determining the mores present in
a stream. The streams of the eastern part of our area are in till which
is sandy and their bottoms are sandy. This material is always slipping
and moving downstream. There are few large stones. The bottom is
not suitable for animals. The swift-water animals are almost entirely
absent. The forms present are those which belong to moderately swift
water.

Composition and subdivisions. — Such streams are poorly populated.
Their mores resemble those of the formations of the pools of streams
eroding coarse material, but the shifting is so much more general and the
species found so different, that it has been thought wise to separate the
two. In the Michigan streams there are in summer a few scattered
plants, which support a considerable number of insects; some of the
brook beetles (Parnidae) are found attached to them. The logs and
roots that happen to be in the water are important; they are the only

102 ANIMAL COMMUNITIES OF STREAMS

places that support any amount of life. From these logs I have taken
hundreds of specimens of small Parnidae, and with them predaceous
diving beetles (Dytiscidae) which were found hiding in the cracks, also
a few scattered caddis-worms (Hydropsyche). The fauna of the bottom
is made up of burrowing and semi-burrowing forms. The little dytiscid
(Hydroporus mellitus Lee.) (99c) is characteristic: it has the habit of
burying itself in the sand. The bivalved mollusks, especially mussels,
are present. From the Deep River (upper course) we have taken
nearly a dozen species. The only snail found is a burrowing form also.
Animals of such a stream are subject to severe conditions. Many
of them burrow. The substratum is very unstable and the logs and
parts of trees to which many of them are attached are free to float down-
stream with every flood. We know nothing of the reactions of these
animals to various stimuli. They are distinctly subjects for investi-
gation.

6. THE SLUGGISH STREAM COMMUNITIES

(Stations 19, 27, 28, and 29; Tables XVII, XVIII, XX-XXV)

There are several phases or types of sluggish stream formations.
The most important of these are the sluggish or base-level creek, the
sluggish river, and the drowned river. These are all illustrated in the
Chicago area.

The sluggish creek type is illustrated by the west branch of the
DuPage River and its tributaries; the upper course of the west branch
of Hickory Creek, Dune Creek, some parts of the Little Calumet south
of Millers, and the Kankakee and some of its tributaries.

The sluggish rivers are the Upper Fox, the lower St. Joseph, the
Grand Calumet, the lower Galien, the lower Black, and others. These
constitute a group of streams representative of the sluggish type about
the Great Lakes.

a) Sluggish creek sub-formations (Stations 16, 18). — The west branch
of Hickory Creek has been studied in a cursory manner. The fish are
a strange mixture of semi-temporary stream and pond forms. The black
bullhead (Ameiurus melas) (79) is probably the most characteristic fish.
The golden shiner (Abramis crysoleucas) and sunfish (Lepomis cyanellus)
are also found.

Baker (100) studied the upper portion of the east-north Chicago
River. He recorded the same species of Mollusca as were taken in the
upper part of Hickory Creek. He records also the black bullhead. The
insects which he mentions are those commonly found in ponds. This

SLUGGISH STREAMS 103

community is distinctly of the pond type in its general mores. Stagna-
tion and low oxygen content and the partial drying of the stream are
tolerated by all the residents.

b) Sluggish river formations. — The conditions in sluggish rivers are
different from those in smaller swift streams in many respects. The
bottom is for the most part of fine materials; there are no rocks. The
difference between pools and rapids no longer exists. The river is a
gently flowing mass with relatively little distinction as to different parts.
The margins of such streams are lined in summer with typical rooted
and holdfast aquatic plants. The small bays and out-of-the-way spots,
out of the current, support bulrushes and sometimes cattails. We can
distinguish several formations in the Fox River: (1) The pelagic forma-
tion, (2) the formation of sand and silt bottom (association of sandy
bottom where the current drags in midstream or beats against the
shore; association of silt bottom where least current is present), and
(3) the formation of the zone of vegetation.

Pelagic formation: This is well developed in the larger rivers, e.g.,
the Illinois River (77). While the Illinois no doubt differs from the Fox
in many respects, doubtless the general features are much the same.
It does not differ greatly from that of Lake Michigan.

Burrowing May-fly or sand and silt bottom formations: On the
bottom in ten feet of water we have found mussels (Anodonta grandis
and Quadrula undulata), the snail (Goniobasis livescens), bloodworms
(Chironomidae), green midge larvae (Chironomidae). On the old mussel
shells were large colonies of the bryozoan Plumatella and occasional
caddis-worms (Hydropsyche) (Figs. 39, 40, p. 96). On sandy bottom,
conditions near the margin are similar to those on the bottom. We
find here also an occasional snail (Goniobasis, Pleurocera, and Campe-
loma), the midge larvae and bloodworms, occasional burrowing May-
fly nymphs, and a number of mussels (Unio gibbosus and Quadrula
rubiginosa being the most characteristic). There is also an occasional
specimen of the long-legged dragon-fly nymph (Macromia taeniolata) and
the black-sided darter. A considerable number of these species occur
in the stillest pools of Hickory Creek, indicating the types that will
dominate later. Silt is often found in particular spots. The most
characteristic animals in this are the large mussel (Quadrula undulata),
the burrowing May-fly nymph (Hexagenia sp.), and the bloodworms
(Chironomidae). There are also the worms (Annelida) which burrow in
the mud and protrude their posterior ends, often also the common
mussel (Lampsilis luteola), the Sphaeridae, and the mud leech (Haemopis

io4

ANIMAL COMMUNITIES OF STREAMS

grandis). All of the animals of the silt formation burrow and prob-
ably require little oxygen.

Planorbis bicarinatus formation, or formation of the vegetation:
Here we have for the first time the conditions which we find in ponds —
a dense rooted vegetation. With such a growth of vegetation we have
a very different fauna: a large number of aquatic insects and pulmonate
(lunged) snails. Of these there are a considerable number of species
which must come to the surface for air, both in the adult and the young
stages. The most important of these are the bugs: water scorpions
(Ranatrafusca), the creeping water-bugs {Pelocoris femoratus), the small
water-bug (Zaitha fluminea), the water-boatmen (Corixa sp.), the still-
water brook beetles or parnids {Elmis quadrinotatus) , several species
of predaceous diving beetles (Dytiscidae) (99c), and water scavengers
(Hydrophilidae). The pulmonate snails are Physa integra, Planorbis
bicarinatus (Figs. 62, 63), and often species of Lymnaea.

Where the bottom is not too soft we often find numbers of viviparous
snails (Campeloma) and an occasional mussel (Anodonta grandis). The
crustaceans are distinctly clear-water forms: the crayfish (Cambarus
propinquus) (101), the amphipod (Hyalella knickerbockeri), and the
brook amphipod (Gammarus fasciatus) (102).

The gilled aquatic insects are the May-fly nymphs (Caenis and
Callibaetis sp.) and the damsel-fly nymphs (Ischnura verlicalis) and
dragon-fly nymphs (Aeschnidae and Libellulidae) . To practically all of
these the vegetation is necessary as a resting-place or clinging-place, or a
place to enable them to creep to the surface to shed the larval skin and
become adult.

Variations of the formation: The Fox is fairly representative of
base-level rivers beyond the reach of tide-water except perhaps that the
presence of gravel and sand in this stream may not seem fully in accord
with this statement. There are, as has been noted, rivers near Chicago
in which these conditions, which go along with old age in a stream, are
still more marked. The lower Deep River is perhaps a good example of
this. It is very sluggish and the bottom in the vicinity of Liverpool,
Ind., is, so far as we have been able to ascertain, entirely covered with
silt, with considerable humus mixed with it. The margins are peaty.
The Calumet and the lower Black are similar. In these, sand and
gravel areas, and animals which inhabit them, are reduced to a mini-
mum and the silt and vegetation associations are better developed.

Characters of the formation: The vegetation formation is distinct
and clearly marked off from all others. The animals are dependent upon

EFFECTS OF DROUGHTS AND FLOODS 105

the vegetation for support. The adult aquatic insects must creep to the
surface of the water to renew their air. The forms that have gills are,
at least many of them, dependent upon the vegetation for crawling to
the surface to molt the old skin. The crustaceans are forms that cling
to the vegetation and the snails must come to the surface for air. Doubt-
less this formation should be divided into strata, but our data do not
justify such division.

III. Special Stream Problems (103, 92)

The first special problem is that of the relations of animals to seasonal
changes, to changes in volume of water, amount of silt, shifting of bottom
materials, and the seasonal aspects of the vegetation. The second prob-
lem of streams is the historic or genetic, which includes the phenomena of
the origin of the animals of the stream, their mode of entrance, and the
effect of rejuvenation, drowning, etc.

I. SEASONAL CHANGES

Streams are more strikingly affected by rainfall and drought than are
any other of the aquatic habitats. In extremely dry years streams dry
up in the rapids where they have perhaps not been dry for a century.
Floods change all the landmarks of the stream bottom and often scatter
the animals of the stream over the flood-plain.

a) Floods. — We found at the side of the high bank of the stream
where the water is quiet at low water, the Johnny darter (Boleosoma
nigrum), the little pickerel (Esox vermiculatus) , the tadpole cat (Schil-
beodes gyrinus), the crayfish (Cambarus virilis), and an occasional
Hydropsyche. Here were also an occasional sphaerid mollusk and one
or two leeches.

Caught in a mass of driftwood behind the roots of a tree were case-
bearing caddis-worms (Phryganeidae), the black-winged damsel-fly
nymph (Calopteryx maculata), the larvae of the black fly (Similium sp.),
and two species of May-fly nymphs (one Heptageninae). The last two
belong to the swift water, the others to the still water or the pools.
During floods the still-water fauna and the swift- water fauna become
mixed in the still places.

At the time of our study there was a growth of rank weeds on the
flood-plain. While the stream had been swollen for a long period and
had stood higher than at the time of observation, little or no invasion
of these weeds by aquatic animals had occurred. Animals evidently
react negatively to such bottom and vegetation.

io6

ANIMAL COMMUNITIES OF STREAMS

We have had but little opportunity to study the swift-water forma-
tion during floods, though some of the riffles in Butterfield Creek have
been studied when the stream was bank full, but no marked changes
were noted. It is obvious that the extreme floods which move large
stones crush large numbers of swift-water animals.

b) Droughts. — There was an unusual drought in the autumn of 1908.
The data on the distribution of fishes in Glencoe Brook and County
Line Creek were collected before this date (Fig. 67, p. 11 1). Table XVI
shows the arrangement after the drought.

TABLE XVI

Showing the Effect of Drought on Fishes
The localities 1, 2, 3, 4 are indicated on the maps of the North-Shore Streams

(Fig. 67, p. in). P = before drought. *P = after drought.

Name of Stream and Common
Name of Fish

Scientific Name

1

2

3

4

County Line Creek

Semotilus atromaculatus . . .

P

P

*p
P

*p

*P

Catostomus commersonii

* p

County Line Creek was entirely dry except the pool nearest its
mouth in September, 1908. This is locality 4 in Fig. 67, p. in.
The following spring was one of normal rainfall. The fish proceeded
upstream a distance of only three rods. This partially restored the usual
arrangement. If this represents the rate, the fish proceed upstream
slowly. Glencoe Brook has not recovered its fish.

As evidence of upstream migration of Mollusca, the following seems
to be important. Frequent examination of a section of the North
Branch of the Chicago River at Edgebrook, between 1903 and 1907,
showed that Pleurocera elevatum and Campeloma occur in this stream.
Pleurocera was not found during this period (ending November, 1907)
above a certain point. Campeloma was found only sparingly above
this point. The spring of 1908 was one of heavy rainfall and the
streams were in flood from April to June. On July 6 the snail
Pleurocera was found in numbers one-fourth of a mile farther up-
stream than formerly. Campeloma had gone nearly as far. The sea-
son from November to April was not different from other seasons
and there is no reason to assume that the migration began before the
spring floods. If this is true the snails could make their way toward

EFFECTS OF DROUGHTS AND FLOODS

107

the headwaters at the rate of at least a mile per year, if they were intro-
duced into a large stream. This must be a response to both water
pressure and current. The small value of such single observations is
recognized but they are presented here because the opportunity to secure
such data is small. In this river there are also notable relations between
especially dry seasons and the distribution of other animals. The
season in which the riffles were dry (October 31, 1907) the pools presented

The Transverse Distribution of Stream Animals

Fig. 64. — Shows the form of bottom and size of bottom materials in a cross-
section of the North Branch of the Chicago River, a-d, natural size (original).

a, a burrowing May-fly nymph (Hexagenia sp.).

b, small bivalve (Sphaerium stamineum), two individuals, two views.

c, viviparous snail (Campeloma integrum) , seen from two sides.

d, the long river snail, young and full grown (Pleurocera elevatum).
Fig. 65. — Cross-section of the stream with reference to a curve.

an unusual aspect. The standing pools were choked with water-net.
The minuter forms, such as protozoa and flatworms, were present in the
greatest profusion. Hydra was abundant. All this is in marked con-
trast to the conditions which one finds when the stream is running.

The season following the dry riffles, we found small Hydropsyche
larvae, and a few young stone-fly nymphs. The only forms present were
those that could be introduced by terrestrial, egg-laying females.

108 ANIMAL COMMUNITIES OF STREAMS

In the autumn of 1906 Professor Child found that the May-fly and
stone-fly nymphs were not present in the riffles but were present in the
moderately swift and more quiet parts below. The spring of 1906 was
a dry spring and the females probably laid their eggs in the moderately
swift instead of the preferred swift water. The distribution is deter-
mined by the conditions at the time of egg laying.

We note that even in the larger streams the weather conditions
affect the presence and absence and abundance of animals. The mores,
however, remain essentially the same.

2. TRANSVERSE STUDIES

Cross-section studies of streams are of interest as showing a hori-
zontal arrangement of forms belonging properly to different formations.
This is best illustrated in the cross-sections of curves where there is a
horizontal gradation of current and in the size of material of the bed.
Figs. 64 and 65 illustrate this. The burrowing May-fly nymph, belonging
to the silt, is in the finest materials of the inside of the curve; passing
toward the center of the stream we next encounter the sphaerid (Sphae-
rium) and a little farther in the snail (Campeloma integrum) , with it often
mussels (A nodontoides ferussacianus) ; and still farther into the stream
we find, clinging to the larger stones, the long snail (Pleurocera elevatum).
While depth of water may be a factor here, the size of bottom material
is of first importance.

3. LONGITUDINAL STUDIES

(Figs. 66, 67, 68, 69)

If one passes from the headwaters of a stream to its mouth, he will
usually find either the spring brook formation or the intermittent
formation in the upper course, the swift-water formations in the middle
course, and the sluggish stream or river formations in the lower course.
There are very numerous variations of this and several of them deserve
comment. Large streams with a large drainage area and much sedi-
ment, and with much of the upper part in a young stage, are subjected
to many changes in the lower courses, such as sil ting-up at the end of the
flood periods and washing out later. This often prevents the development
of the vegetation formation and favors the shifting sand and gravel formations.

a) Rejuvenation, ponding, and retarding of erosion. — Streams are
often dammed by some obstruction in their mid course, or erosion is
checked at a point by a hard stratum, or the stream which has reached
base-level is rejuvenated by a lowering of the water level at the mouth.

LONGITUDINAL STUDIES 109

The obstruction of the hard layer encountered always produces local
swift water. Above this the water may be sluggish and the area reduced
to the general level of the obstruction. In the case of rejuvenation the
head of erosion proceeds upstream ; the part of the stream above the point
to which erosion has reached is sluggish and is sometimes called the pre-
erosion stream.

Of the rivers and creeks which we have considered, nearly all the
larger ones are sluggish or pre-erosion in their upper courses. This is
true of the DesPlaines, which is held in this condition largely by rock
at Riverside. Hickory Creek (Fig. 66) is also of this type, the head of
erosion being at Marley. In passing from source to mouth of such a
stream we find formations arranged as follows: In the upper sluggish
courses of all the streams mentioned we find (1) sluggish creek or
river formations, (2) chiefly swift-water formations below the sluggish,
(3) chiefly gravel bottom formations below the swift- water formation,

a

11

Fig. 66. — Diagrammatic profile of Hickory Creek: A, source; B, mouth; C, head
of erosion; D, rock outcrop. The figures below refer to the columns in Table XXI
and represent parts from which fish were collected.

and (4) typical sluggish river formations farthest downstream where
the vegetation, silt, and sand formations are arranged much as in
the Fox River.

Tables XVIII, XXI, and XXII and Figs. 67-69 show the longi-
tudinal distribution of fishes in six streams. A few moments' study and
comparison of these tables will make the following facts evident :

a) The only species in the youngest stream of the North Shore
series is at the headwaters of all the others.

b) The species found in County Line Creek are found in the same
order in the upper courses of Pettibone Creek and Bull Creek; additional
species are found farther downstream in the larger streams.

c) The same species are at the headwaters of Thorn-Butterfield and
Hickory creeks and in the upper courses of the North Shore streams.
Other species are with them. The species of the North Shore streams
are crowded together in these large streams which have permanent

HO ANIMAL COMMUNITIES OF STREAMS

deeper water at their sources (due to springs) and in which the graded
series of conditions found in the North Shore streams is wanting.

d) The swift-water fishes begin markedly at the head of erosion in
Hickory Creek.

e) The fish communities differ as to species where the conditions
are very similar, for example, in Thorn-Butterfield and Hickory creeks.
The general habits of the fishes are the same.

/) Larger fishes are found in the larger water course and in the down-
stream portions of the smaller streams.

g) Fish, when entering a stream, go upstream to a point suited to
their physiological constitution, regardless of its physiographic mode of
origin.

4. GENETIC ECOLOGY OF STREAMS

Several years ago Adams (103) pointed out that the dispersal of
aquatic animals is determined by the shifting backward of the head-
waters and other conditions in streams as erosion proceeds. The forms
that are in the young streams are moved back as the headwaters are
moved back and as the river system spreads out into the usual fan shape,
the animals that belonged in or near the headwaters move backward as
the conditions migrate backward. In a broad geographic way this is
unquestioned but details may be studied in the small streams of the
bluff between Glencoe and the Wisconsin state line.

Fish are the only strictly aquatic forms in these streams that might
not have entered by some other method than through the mouth of the
stream. We have made a study of the fish of these streams for the pur-
pose of determining whether the fish in the headwaters of the large
streams are the same as the fish that are found in streams that are just
large enough to have a single fish species, and the relation of the animals
to stream development. The changes in animal communities which
take place at one point are called succession.

a) Ecological succession. — Ecological succession is the succession
of ecological types (physiological types, modes of life) over a given point
or locality, due to changes of environmental conditions at that point.
From this point of view we have nothing to do with species, except that names
are necessary. However, we may speak of the succession in terms of
species whenever their life habits {mores) are not easily modifiable.

Succession always involves all the animals of a community but it is
often easier to discuss the changes which take place with respect to one
group, such as the fishes. It is always to be understood that with changes
in the fish communities there are similar changes in the communities of

SUCCESSION OF COMMUNITIES

in

other animals living with them. To illustrate the succession of fish in
streams we shall consider succession of fish in the North Shore streams.

b) Statement of ecological succession. — Succession is a reconstruction.
Here it is based on the superposition of all the fish communities (Fig. 67)
over the oldest part of the oldest and largest stream. To make this
clearer we will state, with the aid of the diagram (Fig. 69), the succession
of fish in Bull Creek. This succession will be considered as taking place

Fig. 67. — Diagrammatic arrangement of the North Shore streams. The streams
are mapped to a scale of one mile to the inch, and the maps are placed as closely
together as possible in the diagram. The intermediate shore-lines are shown in broken
lines which bear no relation to the shore-lines which exist in nature. Toward the top
of the diagram is west. Each number on the diagram refers to the pool nearest the
source of the stream which contains fish, as follows: 1, the horned dace (Semotilus
atromaculatus); 2, the red-bellied dace (Chrosomus erythrogaster); 3, the black-nosed
dace (Rhinichthys atronasus); 4, the suckers and minnows; 5, the pickerel and blunt-
nosed minnow; 6, the sunfish and bass; 7, the pike, chub-sucker, etc. The bluff
referred to is about 60 ft. high. The stippled area is a plain just above the level of the
lake (see Table XVIII).

over the oldest part of the portion of Bull Creek which lies back of the
bluff and higher levels of Lake Michigan. This is the point designated
as 5. (Table XVIII and Figs. 67 and 69 should be before the reader.)
When Bull Creek was at the stage represented by the first stage in
our diagram (which is represented by the present Glencoe Brook), its
fish, if any were present, were ecologically similar to those now in Glencoe
Brook in their relations to all factors except climate. This ecological
type is represented by the horned dace alone. As Bull Creek eroded its

112

ANIMAL COMMUNITIES OF STREAMS

bed and became hypothetical stage C of the diagram, the fish community
of stage i was succeeded by a fish community ecologically similar to the
fish communities at the localities marked 2 in Fig. 67. The fish now eco-
logically representing this community are the horned dace and the red-
bellied dace. The community of the single species, the horned dace,
had at such a period moved inland to the point where line 1-1 (Fig. 69)
crosses the curved line representing the profile of hypothetical stage C.
As erosion continued, the fish community ecologically represented by
the horned dace and red-bellied dace moved gradually inland and was
succeeded by a fish community occupying the mouth of hypothetical

H G F E D C B

\i£jj

Fig. 68. — A diagram showing the successive stages in the profile ("general shape
of the bottom) of a very young stream, curved lines, A-B, A-C, A-D, A-E, A-F,
A-G, A-H representing the successive profiles. The uppermost horizontal line
represents the surface of the land into which the stream is eroding. The horizontal
line with the arrowheads indicates the migration of the source of the stream and
accordingly of similar stream conditions. The vertical line with arrowheads when
followed downward passes through a succession of stream conditions and represents
physiographic succession at the locality B. The point A is the mouth of the stream.
Opposite this are shown three successive sizes of the stream, and therefore succession
at that point.

stage D, ecologically similar to that now found at the point 3. This is
represented by the three daces and the Johnny darter.

As the hypothetical stage D eroded its bed and became stage E,
which is represented by County Line Creek, fish community 3 was then
succeeded by a fish community ecologically similar to the fish community
now present at point 4. This is ecologically represented by the three
daces, the Johnny darter, ancj. the young of the common sucker. The
fish communities designated as 1, 2, 3 have meanwhile moved inland and
are arranged in the order which their ecological constitution requires.

The continuation of the process resulted in displacing a fish com-
munity ecologically similar to the fish community 4 by a fish community

SUCCESSION OF COMMUNITIES

113

ecologically similar to the present fish community 5. This is repre-
sented in the lower waters of Bull Creek — stage F.

Ecological succession is one of the few biological fields in which pre-
diction is possible. We may carry this discussion a little farther. We
have noted that the developing streams continue to erode their beds,
grow larger, and bring down the surface of the land. These processes
have not stopped in Bull Creek; it will become larger, contain a larger
volume of water at the locality 5, and the fish community of locality 5

Fig. 69. — This figure is based on Fig. 68. The profiles of the streams shown
here are separated vertically at the mouth. The curved lines represent seven stream
stages as follows: B, Glencoe Brook; C, hypothetical stage; D, hypothetical stage;
E, County Line Creek; F, Pettibone Creek; G, hypothetical stage; H, Bull Creek-
Dead River. The hypothetical stages could, no doubt, be found along the shore of
Lake Michigan; the difficulty arises from the introduction of sewage into so many
streams.

The comparative size of the mouth of each stream stage is represented by a stream
cross-section at the right. The direction of reading in succession is indicated by the
vertical line with the arrowheads pointing downward. The oblique lines marked
1-1, 2-2, 3-3, etc., pass through points in the stream profiles which are in the same
physiographic condition and occupied by similar fish communities.

will be succeeded by a fish community ecologically similar to that now
at locality 6. This stage has been designated as hypothetical stage G
in the diagram. With a further continuation of the process, the fish
community of stage G, locality 6, will be succeeded by a fish community
ecologically similar to that now found at the locality 7 (Dead River) —
stage H. The communities of every stream have some such history as
we have reconstructed, but the details may be modified by conditions.
That branch of ecology which deals with such histories is called genetic
ecology.

H4

ANIMAL COMMUNITIES OF STREAMS

TABLE XVII

Distribution of Invertebrates in North Shore Streams
The meaning of the numbers is shown in Figs. 67 and 69. a = Temporary pool
{consocies); & = Very young stream and intermittent riffles (ephemeral consocies).

Common Name

Caddis- worm

Mosquito larva

Amphipod

Isopod

Snail

Crayfish

Black-fly larva

May-fly nymph

Crayfish

Burrowing dragon-fly

Dragon-fly nymph. . .

Amphipod

Snail

Crayfish

Crayfish

Crane-fly larva

Amphipod

Snail

Dragon-fly nymph. . .

Scientific Name

Phryganeidae

Anopheles

Eucrangonyx gracilis

Smith

Asellus communis Say.. .
Lymnaea modicella Say. .
Cambarus dio genes Gir . .

Simulium sp

Heptageninae

Cambarus blandingi

acutus Girard

Cordulegaster obliquus

Say

Aeschna constricta Say.. .
Gammarus fasciatus Say .

Physa gyrina Say

Cambarus virilis Hag . . .
Cambarus propinquus Gir
Pedicia albivitta Walk

(rarely)

Hyalella knickerbockeri

Bate

Planorbis campanulatus

Say

Tetragoneuria cynosura

Say

STREAM ANIMALS

"5

TABLE XVIII

Showing the Distribution of Fish (Nomenclature after 79) in the North

Shore Streams at the Times Indicated

(The numbers refer to Figs. 67 and 69)

Name of Stream and Common
Name of Fish

Date and Scientific Name

1

2

3

4

5

6

7

Glencoe Brook

August, 1907

Semotilus atromaculatus. . .

1907-8

Semotilus atromaculatus. . .

Rhinichthys atronasus ....

Boleosoma nigrum

Pimephales promelas

Pimephales notatus

Catostomus commersonii . .
September, 1909, and April,
1910

Semotilus atromaculatus . .

Chrosomus erythrogaster. . .

Rhinichthys atronasus ....

Boleosoma nigrum

Catostomus commersonii. . .
September, 1909

Semotilus atromaculatus. . .

Chrosomus erythrogaster. . .

Rhinichthys atronasus ....

Catostomus commersonii. . .

Pimephales notatus

Esox vermiculatus

Lepomis pallidus

Micro pter us salnioides ....

Esox lucius

*

*

?
*

*

*
*

*
*

*
*
*

*
*
*
*

*
*
*

*
*
*
*
*
*

*

*
*
*

*
*

*

*

*
*
*

*
*

County Line Creek

Horned dace

Black-nosed dace

Johnny darter

Blackhead minnow

Blunt-nosed minnow ....

Common sucker

Pettibone Creekf

Horned dace . .

Red-bellied dace

Black-nosed dace

Johnny darter

Common sucker

Bull Creek-Dead River

Horned dace

Red-bellied dace

Black-nosed dace

Common sucker

Blunt-nosed minnow ....
Little pickerel

*

Bluegill

Large-mouthed black bass
Pike

*
*
*

Crappie

Ponioxis annularis

Moxostoma aureolum

Erimyzon sucetta

Abramis crysoleucas

Notropis cornutus

Notropis cayuga

Schilbeodes gyrinus

*

Red- horse

Chub-sucker

Golden shiner

*
*

*

Common shiner

*

Cayuga minnow

Tadpole cat

*
*

t The lower part of Pettibone Creek has been destroyed by the United States Naval School, other-
wise the table would include the records for a point s and perhaps a point 6, but probably not 7.

Note.— Table XIX follows Table XX.

u6

ANIMAL COMMUNITIES OF STREAMS

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STREAM ANIMALS

117

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ANIMAL COMMUNITIES OF STREAMS

TABLE XIX

Animals of Springs and Spring Brooks
The meaning of the letters in the column headed "Location" is as follows:
Cs = Cary spring; Gs = Gaugars spring; Zs = Zion spring; Sb = Suman spring brook;
Cb = Cary spring brook.

Common Name

Amphipod

Planarian

Planarian

Dragon-fly nymph

Midge larva

Black-fly larva

Caddis-worm

Midge larva

Fly larva

May-fly nymph . . .

Bivalve

Amphipod

Crayfish

Snail

Damsel-fly nymph.
•Parnid

Scientific Name

Gammarus fasciatus Say. . .

Planaria dorotocephala

Dendrocoelum sp

Aeschna sp

T any pus sp

Simulium sp

Hydro psyche sp

Chironomus sp

Dixa sp

Heptagenia

Musculium

Eucrangonyx gracilis Smith
Cambarus propinquus Gir . .

Physa gyrina Say

Calopleryx maculata Beauv
Elmis fastiditus Lee

Location

Cs, Gs, Zs

Cs

Cs

Cs Zs

Sb

Sb, Cb
Cb
Cb
Cb
Cb
Cb
Cb
Cb
Cb
Cb
Cb

STREAM ANIMALS

119

TABLE XXI

The Distribution of Fish (Nomenclature after 79) in Hickory Creek (and
Its West Branch) in the Summer of 1909
Those starred were in the pool nearest the source. I, the first mile of the stream,
measured from the fish pool nearest the source, toward the mouth; II, the third and
fourth miles; III, at the head of erosion, five miles from the pool nearest the source;
IV, six miles from the pool nearest the source; V, nine miles from same; stream much
larger with good riffles and one weedy cove.

Common Name

Scientific Name

I

II

III

IV

V

Horned dace*

Golden shiner*

Setnotilus atromaculatus . .

Abramis crysoleucas

Boleosoma nigrum

Campostoma anomalum . . .

Notropis blennius

Lepomis cyanellus

Pimephales notatus

Catostomus commersonii. . .
Umbra limi

*
*
*
*
*
*
*
*

*

*
*
*
*
*
*
*
*
*
*
*
*
*

*

*
*

*
*

*
*

*
*
*
*

*

*
*

*

*

*

*

*
*
*

*

*

*

Johnny darter*

Stone-roller*

Straw-colored minnow*. . .
Blue-spotted sunfish*. . . .

Blunt-nosed minnow

Common sucker*

Mud minnow

*
*
*
*
*

Top minnow

Fundulus notatus

Chrosomus erythrogaster. . .

Erimyzon sucetta

Ameiurus melas

Red-bellied dace

Chub-sucker

Black bullhead

*

Blackfin

Notropis umbratilis

Hybopsis Kentuckiensis . .

Etheostoma Uabellare

Etheostoma coeruleum ....
Micro perca punctulata. . . .
Phenacobius mirabilis ....
Notropis cayuga

River chub

*

Fan-tailed darter

Rainbow darter

*
*

Least darter

Sucker-mouthed minnow .

Cayuga minnow

Rock bass

*

Ambloplites rupestris

Notropis cornutus

Notropis rubrifrons

Etheostoma zonale

Lepomis pallidus

Lepomis megalotis

Noturus Jlavus

*

Common shiner

*

Rosy-faced minnow

Banded darter

Bluegill

*
*
*

Long-eared sunfish

Stonecat

*
*

Yellow perch

Small-mouthed black bass
Hogsucker

Perca jlavescens

*

Micropterus dolomieu

Catostomus nigricans

M oxo stoma aureolum

*
*

Common red- horse

*

120

ANIMAL COMMUNITIES OF STREAMS

TABLE XXII

The Fish (Nomenclature after 79) of Thorn Creek, Collection Made at the
Headwaters in 1908 and 1909 and at Other Points in
1909 and 1910
A = the first fish pool; B = four miles downstream; C = ten miles downstream.

Common Name

Scientific Name

A

B

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

Horned dace

Blunt-nosed minnow

Blue-spotted sunfish ....
Stone-roller

Banded darter

Common shiner

Striped- top minnow

Black-sided darter

Johnny darter

Mud minnow

Cayuga minnow

Golden shiner

Large-mouthed black bass
Small-mouthed black bass

Bluegill

Crappie

Pirate perch

Yellow perch

Carp

Black bullhead

Common sucker

Short-headed red-horse. . .
Pike

Semotilus atromaculatus
Pimephales notatus ....

Lepomis cyanellus

Campostoma anomalum.
Notropis umbratilis ....

Etheostoma zonale

Notropis comutus

Fundulus dispar

Hadropterus aspro

Boleosoma nigrum

Umbra limi

Notropis cayuga

Abramis crysoleucas. . .
Micropterus salmoides . .
Micropterus dolomieu . .

Lepomis pallidas

Pomoxis sparoides

Aphredoderus say anus . .

Perca flavescens

CypHnus carpio

Ameiurus melas

Catostomus commersonii
Moxostoma breviceps . . .
Esox lucius

STREAM ANIMALS

121

TABLE XXIII
Animals of the DesPlaines, Chicago, and DuPage Rivers
The meaning of the letters in the column headed "Location" is as follows:
L = Liberty ville (still-silt); W = Wheeling (mud-gravel) ; D = DuPage; R = Riverside
(swift-stones). Libertyville is the farthest upstream, and the other situations follow
in the order named. C = Chicago River at Edgebrook, which is added without
regard to longitudinal order.

Common Name

Crayfish

Snail

Dragon-fly nymph. .

Snail

Snail

Crayfish

Crayfish

Mussel

Mussel

Mussel

Mussel

Bivalve

Snail

Mussel

Snail

Snail

Snail

Mussel

Snail

Snail

Stone-flies

Dobson

Amphipod

Caddis- worm

Isopod

Damsel-fly nymph. . ,

Dytiscid

Newt

Polyzoan

Parnid

Caddis- worm

Leech

Caddis-worm

Sialid

Sphaerid

Burrowing dragon-fly
nymph

Scientific Name

Cambarus virilis Hag

Lymnaea humilis modicella Say

Basiaeschna janata Say

Ancylus tardus Say

Ancylus rividaris Say

Cambarus propinquus Gir. . .

Cambarus diogenes Gir

Anodonta grandis Say

Anodontoides ferussacianus Lea

Quadrula undulata Bar

Lampsilis luteola Lam ,

M us culium truncatum Lins. . . ,

Goniobasis livescens Mke ,

Alasmidonta calceola Lea.

Amnicola limosa Say ,

Planorbis bicarinatus Say ....

Physa gyrina Say

Lampsilis ellipsiformis Con . . ,
Pleurocera subulare intensum

Ant

Pleurocera elevatum Say

Perla sp

Corydalis cornuta Linn

Hyalella knickerbockeri Bate. . .

Hydro psyche

Asellus communis Say

Argia sp

Hydroporus vittalus Lee

Diemictylus viridescens Raf . . . .

Plumatella sp

Elmis

Helico psyche sp

Haemopis grandis Verrill

Phryganeidae

Sialis sp

Sphaerium stamineum Con. . . .

Gomphus exilis Selys

Location

D

C
W
C

w

C

w
w
w
w

122 ANIMAL COMMUNITIES OF STREAMS

TABLE XXIV

Mussels of the Calumet-Deep River. Arranged in Order of Longitudinal
Succession Beginning with the Upper Parts of the
River at Ainsworth
The letters indicate place of collection. A = Ainsworth; G = East Gary;
M = south of Miller, in the Little Calumet; and C = Clark, in the Grand Calumet.

Common Name

Scientific Name

Location

Mussel

Symphynota costata Raf

Lampsilis ventricosa Bar

Quadrula undulata Bar

Lampsilis luteola Lam

Symphynota complanata Bar. . .
Unio gibbosus Bar

A
A
A
A
A

G
G
G

M
M
M
M

M
M

Mussel

Mussel

Mussel

Mussel

Quadrula rubiginosa Lea

Anodonta grandis Say

Mussel

C

STREAM ANIMALS

123

TABLE XXV
Animals from a Sluggish Portion of Fox River
The meaning of the letters in the column headed "Location" is as follows:
Gm = gravel in mid river in eight feet of water; G = gravel near shore; S = sand;
M = mudorsilt; V = vegetation.

Common Name

Scientific Name

Location

Snail

Mussel

Mussel

Mussel

Red midge larva .
Green midge larva
Caddis- worm. . . .

Polyzoan

Dragon-fly nymph

Crayfish

Snail

Snail

Mussel

Mussel

Mussel

May-fly nymph . .

Fly larva

May-fly nymph. .

Amphipod

May-fly nymph . .

Beetle

Sialid larva

Snail

Water-boatman. .
Water scorpion. . .

Amphipod

Bug

Parnid

Creeping bug

Back-swimmer. . .
Dragon-fly nymph

Leech

Top minnow

Snail

Goniobasis livescens Mke
Anodonta grandis Say. .
Lampsilis ligamentina Lam
Quadrula undulata Bar.

Chironomus

Chironomus

Hydro psyche

Plumatella

Macromia taeniolaia Ram.
Cambarus propinquus Gir.
Campeloma integrum DeK.
Pleurocera elevatum Say. . .

Unio gibbosus Bar

Quadrula rubiginosa Lea. .
Lampsilis luteola Lam. . . .

Hexagenia

Slratiomyia sp

Callibaetis sp

Hyalella knickerbockeri Ba.

Caenis sp

Donacia

Chauliodes sp

Physa inlegra Hald

Corixa sp

Ranatra fuse a Beau

Gammarus fasciatus Say. .

Zaitha fluminea Say

Elmis 4 notatus Say

Pelocoris femoratus Pal

Beauv

Notonecta variabilis Fieb . .
Ischnura veriicalis Say.. . .
Glossiphonia fusca Castle .
Fundulus diaphanus

menona J. and C

Planorbis bicarinatus Say.

Gm
Gm
Gm
Gm
Gm
Gm
Gm
Gm

M

CHAPTER VII

ANIMAL COMMUNITIES OF SMALL LAKES

I. Introduction

Lakes are difficult to classify on the basis of animal relations. This
is because size, shape, exposure to wind, depth, and age are all important
in determining conditions that affect animals. A classification into
coastal lakes and morainic lakes will serve our purposes best, because,
other things being equal, it represents age and depth (near Chicago).

Morainic lakes are depressions in the moraine due to irregularities of
deposition, which stand below ground-water level. They are of various
sizes. We shall apply the term lake only to those bodies of water that
are large enough to produce an area of at least a few square rods of
sandy shore, which supports gilled snails, mussels, etc. The principal
lakes included in our area are shown on the map facing p. 52. The
largest of these are the Fox, Pistakee, Maria, and Grass lakes in northern
Illinois; Hudson, Cedar, Stone, and Flint lakes in Indiana; and Paw
Paw and Pipestone lakes in Michigan. The only coastal lakes of any
size are Wolf Lake and Calumet Lake. These are located in the old Lake
Chicago plain.

I. CONDITIONS IN LAKES

Depth is important in determining the conditions at the bottom, but
is of little importance to the other parts of the lake. Little is known of
the depths of our lakes. Exposure to wind is of importance in affecting
the waves and circulation of the water (see p. 61), both of which are
important to animals. A lake well protected by high hills will be likely
to be less affected by wind than others. Shape is also a factor. Long
lakes whose long axes are parallel with the direction of the prevailing
winds are more strikingly affected by the wind than those with the long
axis at right angles to the wind.

Waves are never large on small lakes, but are usually effective in
determining the kind of bottom by controlling erosion and deposition.
The general circulation of all pur lakes has not been studied. On
account of their small size it is probable that the deeper ones at least
have an incomplete circulation like that indicated in Fig. 11, p. 61.
Those that get warmed throughout in summer probably have a complete
circulation. The dissolved content of the waters of lakes is usually

124

LIMNETIC COMMUNITY

I2 5

similar to that of the large lakes and rivers. Oxygen is usually abundant
in the surface waters, but is often wanting in the bottoms of lakes (74)
with incomplete summer circulation. Muck bottoms in deep water
or in bays have little or no dissolved oxygen. Dissolved nitrogen is
important, but has been little studied. In the open water light and
pressure are governed by the same factors as in the large lakes (see
pp. 62-64). The bottom in small lakes varies with exposure to waves.
Where the waves are eroding, the bottom is stony or sandy; where deposit-
ing, it contains silt and humus. There are often deposits of marl, which is
a calcium carbonate deposit, frequently reaching a depth of 18 feet in the
Indiana lakes. It frequently reaches to the surface of the water, but
when it does so is often covered by muck. Muck bottom is common in
the deeper water and in bays. The vegetation in such lakes is very much
like that in base-level streams. The vegetation of the shores of rivers
like Fox River is duplicated in these lakes, and in fact, small lakes are
strictly comparable to sluggish rivers in many respects. We have
patches of vegetation, patches of sand and gravel bottom, but also much
bottom which has more organic matter than river silt. The principal
difference is that currents in the lakes vary with the wind, and in sluggish
streams are mainly in one direction.

II. Communities of Small Lakes

(Stations 30, 30a, 31; Table XXVI)

These are divided into the limnetic formation, the formations of

sandy and stony shores, the formations of muck bottom in shallow

water, the formations of the vegetation, and the formations of deep

water (anaerobic).

I. THE LIMNETIC FORMATION (104)

(List II)
The limnetic formation of the smaller lakes is very similar to that of
the larger lakes. It is made up of the same groups, but with the addition
of a few pelagic insects such as the phantom larva (Corethra sp.). The
species of crustaceans, rotifers, and protozoa are different. The char-
acters of the formation are similar to those of Lake Michigan (p. 75).

2. SHALLOW WATER FORMATIONS

a) Terrigenous bottom formation (105). — Vegetation sparse or absent
— water 0-3 meters. Crawling over the sandy bottom are usually found
caddis-worms {Goer a sp. or Molanna sp.) (Figs. 70, 71). These forms

126

COMMUNITIES OF SMALL LAKES

belong to different families, but have similar cases and similar habits.
This is a good example of what is meant by mores. The forms are very-
different, but their mores are similar. The Johnny darter, the straw-
colored minnow (Fig. 72), and the blunt-nosed minnow are usually
found (105) in the shallowest water. The Johnny darter, the blunt-
nosed minnow, the miller's thumb, and probably other minnows breed
in these situations (105, 106). Crayfish are common here (in Wolf Lake,
Cambarus virilis).

Snails (such as Pleurocera subulare [Fig. 73], and sometimes Goniobasis
livescens) are common on the shoals, crawling over the bottom which is
always covered with diatoms, desmids, etc. These algae serve as food

for the mussels. Miss Nichols
found 16 species of algae on the
shell of a specimen of Pleurocera
taken from a Wolf Lake shoal.
In the deeper waters (3 ft.) we
find the same crayfishes and the
same snails fewer in number
than in the shallower parts of
the shoals. Associated with
them are the mussels (especially
Lampsilis luteola,Anodonta mar-
ginata and grandis) . Such sandy
and gravelly bottomed shoals in
1-3 ft. of water are especially
important to the food fishes.
There are many first-class food
fishes in all such lakes. Of
those in Wolf Lake seven breed
in these shallows. There are the large-mouthed black bass (Fig. 74),
thebluegill, the pumpkinseed, the green sunfish, the perch (Fig. 75), the
speckled catfish, and the crappie. Nearly all in making their nests
scrape the bottom clear of all debris; the males guard the nests. The
number of food fishes in a lake is related to the area of such shoals, which
are accordingly of great economic importance and should be protected
from destruction by the encroachment of vegetation and accumulation
of debris. Associated with the fish are occasional musk turtles (Aro-
mochelys odorata). Shoals are invaded by bulrushes and bare bottom
may exist between them. Here the viviparous snail (Vivipara contec-
toides) (Fig. 76) sometimes occurs.

Fig. 70. — The case of a caddis-worm {M ol-
anna sp.), sandy bottom (Fox Lake, 111.)
(original).

Fig. 71. — The same from below.

BOTTOM COMMUNITIES

Representatives of the Bare Sand Community
Fig> 72 — Straw-colored minnow (Notropis blennius) (from Forbes and Rich-
ardson).

FlG< 73 ._Snail (Pleurocera subulare) crawling over sandy bottom; slightly
enlarged (photographed in aquarium).

FlG> 74 ._Large-mouthed black bass {Micropterns salmoides), juvenile; natural
size (original).

128

COMMUNITIES OF SMALL LAKES

Characters of the formation : The formation is distinctly dependent
upon a clean bottom of sand or coarser materials, and is made up of
creeping forms and those using the bottom as a breeding-place.

Representative Animals of the Submerged Vegetation

Fig. 75. — Upper fish, the green sunfish (Lepomis cyanellus) ; lower fish, the yellow
perch (Perca flavescens) ; both juvenile; slightly reduced (original).

Fig. 76. — A viviparous snail (Vivipara contectoides) ; natural size.

Fig. 77. — A winter body or statoblast, of the gelatin-secreting polyzoan (Pectina-
tella magnified); 10 times natural size (original).

Fig. 78. — A shrimp {Palaemonetes paliidosus) ; twice natural size (original) .

b) Submerged vegetation association of the open waters. — A lake of the
coastal type is separated rapidly from the larger body of water in con-
nection with which it is formed, or a morainic lake, when the ice retreats,

VEGETATION COMMUNITIES 129

is left with the greater part of its shallow water of the type which we have
described. Vegetation is present from the first in the form of floating
microscopic plants, and the dead bodies of these and of the animals
present are swept into the depressions and protected situations where the
waves do not drag on the bottom. Here vegetation grows in the greatest
luxuriance and causes the production of more plant debris, which adds
to that already in the protected situations. We then have, after a time,
a covering of the bottom by the humus and conditions unfavorable for
most bottom animals. The animals of the bare bottom shoals are no
longer present in numbers. Small, apparently stunted forms of Lampsilis
luteola are found for a time, but are soon driven out by the increase of
humus and vegetation. The early vegetation is made up of scattered
aquatic plants, such as Myriophyllum and Elodea, and in the shallower
water usually bulrushes.

One of the most distinctive and characteristic forms of such lakes is a
transparent true shrimp (Palaemonetes paludosus), about 2 inches long
(Fig. 78), which is a close relative of some of the edible marine shrimps.
In spring they are found carrying numbers of green eggs attached to the
appendages of their abdomens. Another common animal in these
situations is the large polyzoan (Pedinatella magnified). This is a
colonial form which reproduces by budding in several directions. It also
secretes a clear and transparent jelly. As the number of animals
increases the amount of jelly increases on all sides and the animals are
arranged on the outside of the more or less spherical mass of jelly; the
necessary increase in surface for the growth of the colony is supplied
through additional secretion by each new animal added. Some of these
masses of jelly reach a size of 6 inches in diameter. They are often
attached about a stalk of Myriophyllum as a center. In the autumn
they form bodies known as statoblasts (Fig. 77), which are disk-shaped,
the center containing living cells and the rim being filled with air-bubbles.
The rim of the disk is supplied with hooks which catch onto objects.
Probably they must be frozen before they will grow into new colonies
for they do so only in the spring.

Other characteristic animals of this open-water vegetation are
shelled protozoa (Fig. 79), water-mites (Fig. 80), and ostracods (Fig. 81).
On the stems of the water plants, such as bulrushes and pickerel weed,
are the snails (Ancylus) which belong to the lunged group, but are said
to take water into the lung and thus do not need to come to the surface
for air. Occasional snails, leeches, and midge larvae occur. Water-
mites fasten their eggs to the bases of the aquatic plants. Among the

i3o

COMMUNITIES OF SMALL LAKES

leaves of the divided leaved plants the midge larvae, damsel-fly nymphs,
and May-fly nymphs (Callibaetis sp.) are usually numerous. All these
are important as fish food. This area is the feeding-place for a number
of fishes. Those feeding in the vegetation are the subfishes, basses and
perches, most of which breed on the barren shoals. With them are also
the carp, the chub-sucker, the warmouth bass, the brook silverside
(Labidesthes sicculus), and the buffalo fish (84). This part of the lake is
also the favorite haunt of the turtles (107), such as the soft shell (Aspi-
donectes spinifer), and in the parts with some bare bottom the musk

^

80 * 81#

Fig. 79. — Shelled protozoan (Difflugia pyriformis Verty .) (after Leidy).
Fig. 80. — A red mite {Limnochares aquaticus) ; 6 times natural size (after Wolcott) .
Fig. 81. — Dorsal view of an ostracod (Cypridopsis vidua)] 80 times natural size
(after Brady).

Fig. 8i#. — The same seen from the side.

turtle (Aromochelys odorata), and the geographic turtle (Graptemys geo-
graphicus). The mud puppy (Necturus maculosus) is also found in such
situations (fide Mr. Hildebrand). The muskrat (Fiber zibethicus)
builds its nest (Fig. 82) in the. shallow water adjoining these situations.
The musk turtle frequently deposits its eggs on the nest in early
summer (105). We have found them in these situations in the month
of June. Various aquatic birds feed here (108). This formation may
be characterized as belonging to the aquatic vegetation, but practically

VEGETATION COMMUNITIES

131

all the species are relatively independent of the atmosphere and of the
bottom.

c) Emerging vegetation association of bays. — Such situations as are
occupied by this association are found in bays and protected situations in
the larger lakes and represent a stage which is last in the history of a
lake. Water-lilies, water buttercups, and Myriophyllum are the prin-
cipal plants. Filamentous algae are usually very abundant. Logs,
sticks, and pieces of wood are not uncommon.

On the under side of logs, we find such forms as the polyzoan
(Plumatella) and sponges (Spongilla sp.). On the under side of the water-
lily pads are usually numbers of Hydra together with great numbers of

Fig. 82. — A muskrat's nest adjoining the lake border among the bulrushes on
sandy bottom.

shelled protozoans and rotifers, especially sessile forms. Snails also are
common here (Segmentina armigera, Planorbis parvus, Physa gyrina and
integra, Planorbis campanulatus, and some species of Lymnaed).

A large number of species of aquatic insects cling in the vegetation
with the abdomen near the surface of the water and secure air through
various anatomical arrangements which conduct it to the spiracles; the
most noteworthy of these are the water scorpion (Ranatra), the electric-
light bugs (Benacus and Belostoma), the predaceous diving beetles
(Dytiscidae) (99c), the water scavengers (Hydro philidae), and the water-
boatmen (Corixa). There are also a number of aquatic insects that are
not dependent upon the atmospheric air in their young stages. They
require, however, some object which reaches above the surface of the

132 COMMUNITIES OF SMALL LAKES

water when they emerge from the larval skin. The prominent members
of this group are the dragon-fly nymphs (Anax Junius and Ischnura
verticalis).

There are a few insects that are relatively independent of vegetation
as a means of attachment. The back-swimmers are an example. They
float or swim in the water among the vegetation. The commonest of
these are those belonging to the genera Plea, Notonecta, and Buenoa.
There are a few fish that have a similar habit. The top minnow
{Fundulus dispar), which feeds at the surface, is an example. It invades
the pools near shore and devours mosquito larvae. The young of such
fishes as the basses and the sunfishes are sometimes taken in these
situations.

In the mud of the bottom there are but few animals. Some of these
are the same species as those found in the bottom in the region of open
water and will be discussed later. There are, however, forms that live
only on the rhizomes of the water-lily. Certain of the leaf-feeding
beetles (Chrysomelidae, Donatio) (109) are aquatic in the young stages.
The female eats a hole in the leaves of the water-lilies and reaches
through with her ovipositor and deposits the eggs in a semicircle which
has the hole as its center. When these eggs hatch the larvae crawl to the
rhizomes. They are not provided with gills and do not come to the
surface for air. They have a pair of spines adjoining the spiracles.
These spines are thrust into the plant and the spiracles which open at
their bases come into contact with the holes; the gas in the plant and
the gas in the air tube of the insect's body interchange, and the animal is
thus supplied with oxygen. When the larva is ready to pupate it spins
a cocoon in some unknown way under water, but when it is completed
it is filled with gas, not water, and surrounds the body of the animal.
The animal then eats a hole, connecting the cocoon with the air spaces
of the plant. It then pupates and is supplied with oxygen by the plant
during the entire pupal period.

The common painted turtle (Chrysemys marginata) and the snapping
turtle are common in such small bays. They come out upon the logs and
bask in the sun. The pied billed grebe builds its floating nest, and many
other aquatic birds feed in such situations (108).

Characters of the vegetation formation: This formation is of the
old-pond type which will be especially discussed in the following chapter.
There are two characters, one or the other of which is possessed by
nearly all the animals. They depend upon the atmospheric air or must
have the support of the vegetation, or both. The majority of the ani-
mals of this formation stick their eggs either in or on vegetation. Such

SUCCESSION OF COMMUNITIES 133

formations are quite similar in many respects to the formations of the
vegetation in sluggish rivers but resist lack of oxygen and stagnant
water much better.

d) The anaerobic formation. — This is the bottom and deep-water
formation. We have already stated that the circulation of water (see
Fig. 10, p. 61) is not known for any of the lakes discussed. Old lakes like
those about Chicago are usually covered with humus on the bottom. In
this humus and probably just above it there is little or no oxygen.
Analyses of the bottom water from ponds with humus-covered bottoms
showed that it contained no oxygen. The open water of the lakes with
the incomplete circulation in summer is without sufficient oxygen to
support life, below the level of circulation (Fig. 11, p. 61). There
are, however, numbers of animals that pass the summer under these
conditions (no, in). These are protozoa belonging to eleven genera,
worms belonging to two genera, one rotifer, one ostracod, and the small
bivalve (Pisidium idahoense). Dr. Juday kept these animals in jars
without oxygen and observed their activities. The rotifer was always
active. The ostracod showed little activity, and the bivalve kept its
valve closed, showing no activity whatever.

There are occasional midge larvae in the mud of such bottoms, but
they are rare. Some of these have haemaglobin in their blood and are
supposed to be able to use oxygen when it is present in the minutest
quantities. In the open oxygenless water there are phantom larvae
(Corethra) which are able to carry a supply of oxygen with them from
the surface.

III. Succession in Lakes

The general tendency of succession in lakes has been indicated. The
first formation is the bare-bottom type, which is locally transformed to
the vegetation of open- water type. This usually begins in the protected
situations first; the bays are ecologically oldest. These bays pass
rapidly from the third open-lake type to the bay conditions. When such
a stage has been reached the situations that have a less degree of protec-
tion from waves have reached the second stage and we have lakes as we
find most of the larger ones about Chicago. They contain, at various
points, the three formations which we have discussed. The lake is
reduced in size by filling near its shores and the lowering of its outlet.
The older stages are continuously encroaching on the younger. The
area of barren shoal is constantly becoming less as the lake fills and the
outlet, if it has one, is lowered. Around the shores the development of
prairie or forest is usually well begun and one or the other of these types
of land vegetation finally displaces the h,ke.

134 COMMUNITIES OF SMALL LAKES

I. THE INFLUENCE OF SIZE AND DEPTH

Size and depth have a marked influence on the rate of succession.
If the lake is large, like Lake Michigan, its waves beat upon the shores
with such force as to prevent the development of vegetation or the
establishment of any of the formations just discussed. Smaller lakes
have proportionally less efficient wave-action, and situations which would
not be protected to any marked degree in a lake like Lake Michigan are
relatively free from effective wave-action. The formations succeed one
another rapidly where wave-action is slight. The various parts of the
shore of a small kettle-hole with a regular shore-line would pass through all
these stages at nearly the same rate. Depth is an important factor also
because the various formations cannot succeed over the deep water until
the deeper parts are filled (or drained), which often requires long periods.
The rate of succession in lakes is then directly proportional to their size
and depth. The small lakes pass through all the stages more quickly
than the larger lakes. Those considered here have for the most part, at
present, become dominated by the late stages. The lakes of the inland
type which are large enough to maintain all the formations discussed are
among the most complex of all our habitats.

2. INFLUENCE OF MATERIAL AND MODE OF ORIGIN

At the very beginning the kind of material in which a lake is situated
is important but as time goes on it becomes less and less important. If
the lake is in clay, at the outset there are no sandy areas, but the action
of the waves soon removes the finer material and leaves sand (the finer
materials being deposited on the bottom of the lake). Young lakes in
rock are probably very different from those in clay, but even here sandy
shores are soon formed and occupied by the same animals as sandy
shores of different origin.

The distinction between lakes and ponds is a purely artificial one.
The ponds have the same communities at the outset as the lakes, but
the changes proceed so rapidly that very young ponds are rare. All
lakes and ponds tend to become ecologically similar, regardless of mode
of origin and kind of material.

LIST II
The following Entomostraca have been taken from Wolf Lake: * indicates the
species is found in Fox Lake; f in Butler's Lake; % in the series of ponds at the
head of Lake Michigan: Copepods: %*\ Cyclops serrulatus Fischer; *fj C.albidus
Jurine; %C. viridis brevispinosus Herrick. Cladocerans: Acroperus harpae Baird;
t Scapholeberis mucronala Muel.; % Pleuroxus denticulatus Birge; Diaphanosoma
brachyurum Liev.; J Chydorus sphaericus Muel. ; Polyphemus pediculus Linn; Macrothrix
rosea Jurine; % Ceriodaphnia reticulata Jurine; % Simocephalus serrulatus Koch; Bosmina
obtusirostris Sars. Ostracods : Potamocypris smaragdina Vav.

SMALL LAKE ANIMALS

135

TABLE XXVI

Animals from Small Lakes

Meaning of letters occurring in the columns is as follows: "Habitat" column:

S = bottom of sand; SH = bottom of sand and humus; B = bulrush vegetation; VO =

vegetation of open water; VB = vegetation of bays; in "Lake Where Recorded"

column: F = FcxLake; W = Wolf Lake; G = Lake George; B = Butler's Lake.

Common Name

Scientific Name

Habitat from

Lake \

Which Collected

Recoi

S

w

S

F

S

S

W

s

W

s

W

s

W

s

W

s

W

s

W,F

SSHB

W,F

S,SH

S

W.F

s

W

S,SH

S,SH

S,SH,B

W

B

VO

B

VO

W,F

B

VO

W,F

B

VO

B

VO

W,F

VO,VB

W

VO,VB

W

VO,VB

W

VO,VB

W

VO.VB

W

VB

W

VB

F

VB

VB

W

VB

F

VB

VB

W

VB

F

VB

F

VB

F

VB

W

VB

W

VB

F

VB

VB

VB

W

Caddis-worm

Caddis- worm

Caddis- worm

Snail

Snail

Crayfish

Turtle (musk)

Geographic turtle ....
Straw-colored minnow

Johnny darter

Mussel

Planarian

Mussel

Mussel

Polyzoan

Leech

Brook silverside

Snail

Snail

Midges

Amphipod

May-fly nymph

Dragon-fly nymph . . .

Polyzoan

Shrimp

Cricket-frog

Top minnow

Snail

Snail

Snail

Damsel-fly nymph . . .
Dragon-fly nymph . . .
Dragon-fly nymph . . .

Back-swimmer

Back-swimmer

Back-swimmer

Back-swimmer

Leech

May-fly

Isopod

Bug

Beetle

Beetle

Goer a sp

Molanna sp

Polycentropidae

Pleurocera subulare Lea . . .
Goniobasis livescens Mke. . .

Cambarus virilis Hag

Aromochelys odorata Lat. . .
Graptemys geographicus LeS

Notropis blennius Gir

Boleosoma nigrum Raf ....

Lampsilis luteola Lam

Planaria maculata Leidy. . .

Anodonta grandis Say

A nodonta marginata Say. . .
Plumatella polymorpha Kraep
Placobdella parasitica Say. . . .
Labidesthes sicculus Cope ....

Ancylus fuscus Adams

Segmentina armigera Say ....

Chironomus sp

Hyalella knickerbockeri Bate. .

Callibaetis sp

Ischnura verticalis Say

Pectinatella magnified Leidy. .
Palaemonetes paludosus Gib . .

Acris gryllus Lee

Fundulus dispar Ag

Physa gyrina Say

Planorbis campanulatus Say. .

Planorbis parvus Say

Enallagma sp

Tetragoneuria cynosura Say . .

Anax Junius Dru

Buenoa platycnemis Fieb

Notonecta variabilis Fieb

Plea striola Fab

Notonecta undulata Say

Macrobdella decora Say

Ephemerella excrucians Walsh
Mancasellus danielsi Rich. . . .

Zaitha fluminea Say

Coptotomus interrogans Fab. .
Donacia sp

CHAPTER VIII

ANIMAL COMMUNITIES OF PONDS

I. Introduction

Ponds are fascinating to all, and do not lack interest from the scien-
tific point of view. They are of especial interest to those familiar with
the laboratory study of zoology. The common animals of the laboratory
are pond animals, because pond animals are forms that will live in
stagnant water. The common aquarium fishes are all pond fishes, as
the brook forms die quickly if they are not supplied with running water.
The frog, so much studied, is a pond form. The conditions in ponds are
different from those in lakes and streams, because currents are not strong
nor particularly important. The water doubtless piles up at one side
or end of a pond during strong winds, and a complete circulation is
effected, but this is not important. All of the conditions of lakes are
duplicated in ponds, but on a smaller scale. One of the chief differences
between ponds and lakes is the vegetation. Ponds are usually very
largely captured by vegetation which is very much like that in the bays
of lakes. Succession of plants in ponds is similar to that in lakes; the
age of a pond is therefore a matter of first importance. The bottom
materials are of most importance at the beginning (6, 112). The bottom
materials in the ponds of the Chicago area are rock, clay, and sand.
Rock-bottomed ponds have been but little studied, though there are a
number of ponds in abandoned quarries of different ages which would
make a good series for investigation. Clay bottom occurs in the moraine
area. Nearly all the natural clay-bottomed ponds have reached a stage
at which the bottom is not important, but one could no doubt find a
good series if he were to make a special study. Sand-bottomed ponds
are the commonest of all, and for the purpose of studying the effect of
age upon ponds, a series of sandy-bottomed ponds, which differed chiefly
in the matter of age, was selected.

II. Area of Special Study

The ponds that have been made the subject of special study lie in
the sand area at the south end of Lake Michigan, within the corporate
limits of the city of Gary, Ind. They may be reached from the stations
known as Pine, Clark Junction, and Bufiington (Fig. 84). The locality

136

ORIGIN OF PONDS

137

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138

POND COMMUNITIES

is characterized by a series of ridges running parallel with the shores of
the lake. Their average width is about 30 meters (100 ft.), and they are
separated by ponds somewhat narrower. Most of the ponds are several
miles long and vary in depth, during the spring high water, from a few
inches to 4 or 5 ft. Originally there were probably a number of outlets
to the ponds, either connecting them with the lake or with the Calumet
River. This river flows across the long ponds at a small angle. The
ponds and ridges were formed under water, and the river has cut its
way across them with the falling of the lake level. The building of
sewers associated with the growth of the Northern Indiana towns has
drained a number of the ponds, and roads and railroads have isolated
parts of others.

I. ORIGIN OF THE PONDS (62)

The waters of the lake appear to have fallen gradually from the 12-ft.
level referred to on p. 47. There are at present usually two or three
depressions along the shore of the lake under the water. The present
submerged depressions and ridges appear to be strictly comparable
to those found on the plain of Lake Chicago, and the ones with which
we have to deal probably belong to a series formed by the continuous
recession of the lake level (Fig. 83). This gives us a series of pcnds
differing principally in age, the oldest being farthest from, and the
youngest nearest to, the lake.

As has been stated, the ponds have been partly drained, so that we
have been obliged to study isolated portions. The younger members
of the series (1st, 5th, 7th, and 14th, as counted from the lake) show the
greatest differences and have, accordingly, been studied in detail. The
arrangement of these ponds is shown in Fig. 83. In addition to the
ponds named, the 13th, the 5 2d, the 93d, and the 95th have been
studied, but with less care.

2. PHYSICAL CHARACTERISTICS (112)

The main facts of the topography of the isolated portions studied
are shown in Table XX Via.

TABLE XXVIa

Pond

Area in Sq. M.

Depth in Meters

Average Depth

Slope 3-7 °

Slope 20

I

3,500

3>500

25,000

10,000

50,000

630

0.6
0.9
0.9
O.667

0.5
0.4

03
o-5
0.5
0.4
O. 2
O.I

Much
Less

Very little
Very little
Very little
Very little

Little

c

Much

7

Much

14

All

30

All

C2

All

ORIGIN OF PONDS

139

140 POND COMMUNITIES

A decrease in depth, due to the accumulation of humus and the lowering
of the ground-water level, is to be noted in the older ponds. The series
is, then, an ecological age-series, and throughout our discussion we refer
to earlier and later phases of the various associations concerned.

III. Communities of Ponds

I. THE PELAGIC FORMATION

We have in the ponds a pelagic formation. Though it is limited
in number of species, many of which breed on the bottom, it is similar
to that of larger lakes. We have found little difference in the pelagic
species inhabiting younger and older permanent ponds. Diaptomus
reighardi has not been taken from ponds filled with the vegetation
which reaches the surface. Other species are about the same in
the different permanent ponds. The pelagic formation is poorly
developed.

2. PIONEER FORMATION (TERRIGENOUS BOTTOM)

(Ponds, i, 5, 7) (113) (Stations 9 and 32; Tables XXVII and XXXIV)

The youngest ponds of the Chicago area are near Waukegan. The
outer end of the Dead River receives the force of the winter waves from
the lake and the bottom is bare, with a few scattered aquatic plants.
Here animals are few. We have taken only a few invertebrates. The
fish present probably get their food from the older parts farther back
from the lake. The fish are: the pike (Esox lucius) which prefers clear,
clean, cool water (79); the red-horse {Moxostoma aureolum) which dies
in the aquarium if the water is the least bit impure, and which also suc-
cumbs to any impurities in its natural environment (79); Notropis
cayuga, which prefers clear waters; the common shiner (Notropis
cornutus) which breeds on bare bottom (105), and the white crappie
{Pomoxis annularis) which lives in streams. On the bottom at such a
period one is likely to find the larvae of caddis-flies {Goer a sp.), snails,
mussels, etc., but we have found none in the Dead River.

Vegetation quickly captures parts of such a pond. Chara is the
first plant to cover parts of the bottom. After this has happened, the
pioneer formation may still continue. In Pond 1 of the series of special
study (Fig. 85) we have a considerable area of bare sand, and the forms
present are the caddis- worm (Goer a sp.) and the mussels (Anodonta
marginata and grandis, and Lampsilis luteola). These are preyed upon
by muskrats (Fig. 86). There are a number of fish that belong to this

PIONEER COMMUNITIES

141

formation because of their breeding relations. The large-mouthed
black bass, the bluegill, the pumpkin-seed, and the speckled bullhead
all make nests on the sand, the male fish guarding the nests and driving
off other fish that approach. These species are the same as those of the
bare-bottom formations of a lake. In their feeding the fish belong in
part to another formation in the pond, namely, that of the chara.

Character of the formation : The formation may be designated as the
bare-bottom formation, the forms present being those that are dependent

BE? 'Sg^-. j~ .^SLfc. ^te.

m , M

,,'- . "~

Fig. 85. — Shows Pond 1 at the extreme low water of the drought of igoS. In the
spring the old boat is usually covered with water. In the foreground a large area of
bare sand bottom is shown; to the right a few rushes and sedges. The absence of
shrubs near the water's edge should be noted.

upon bare bottom in their most important activities — the fish in breeding,
the caddis- worms in making their cases, the mussels in their general
activities. It is necessary for the mussels to be on bare bottom in order
to maintain themselves in an upright position.

Tendencies in the formation: This formation is similar to that of the
bare bottom of lakes. The vegetation comes in, as has been indicated in
the protected situations, and the bare bottom disappears, its place being
taken by the chara. The chara gives rise to humus, upon which chara

i 4 2 POND COMMUNITIES

will grow for a long time, so the bottom becomes a humus- and chara-
covered bottom.

3. THE SUBMERGED VEGETATION ASSOCIATION

(Ponds 1, 5, and 7; Stations 32, 33, and 34)
The Chara community is entirely different from that of the bare
bottom, and differs also from that of other vegetations. Chara is highly
siliceous. It is probably eaten only accidentally by animals or at least
forms no important part of their food. It should be considered simply as
a covering for the bottom and a resting- and living-place for animals.
Some fish culturists (113) have said that it is very rich in life. This
may be true under certain artificial pond conditions; but the chara
ponds are poorer than any others of our series. Chara differs from some
other plants in not reaching to the surface of the water. Many aquatic
insects that carry air beneath the surface must cling to objects which
reach the surface when obtaining a fresh supply, and others must crawl
to the surface on some object in order to emerge from the nymphal skin
(96). Associated with chara are often growths of bulrushes near the
sides of the ponds and on the sterile bottom. In the sparse chara the
most characteristic animal forms are Anodonta grandis footiana (Fig. 86),
and the musk turtle (Aromochelys odorata), which is abundant on these
bottoms but is not found elsewhere. There are often nests of a few un-
identified fishes that clear off the bottom in building. The burrowing
dragon-fly nymph (Fig. 87) lives on the bottom among sparse chara, in
the presence of but little oxygen. It lies half buried in the mud, with its
abdomen protruding a little at the end. The mud minnow (Umbra limi)
(Fig. 88), the golden shiner (Abramis crysoleucas) (Fig. ^) y the chub-
sucker (Erimyzon sucetta), bullheads, the little pickerel (Esox vermicula-
tus), the tadpole cat (Schilbeodes gyrinus), and occasionally the warmouth
bass (Chaenobryttus gulosus) spend their time in the denser chara. The
shiner and mud minnow place their eggs on the chara or other plants.

Among the most abundant forms in the association are the midge
larvae (Chironomus); these (Figs. 89, 90, 91) are present sticking to the
vegetation in their small silken cases in great numbers (81). They are
important articles in the food of the fishes. Aquatic insects are not
numerous except for the midge larvae and a little May-fly. Others
are occasional horseflies (Fig. 92), damsel-fly nymphs, May-fly nymphs
(Siphlurus sp.), and occasional dragon-fly nymphs (Tramea, Anax,
Leucorhinia). There are also a number of dytiscid beetles, many of
which are common in all shallow waters, even rain pools, because of
their powers of flight.

PIONEER COMMUNITIES

H3

Ecologically one of the most interesting insects is a caddis-worm
(Leptoceridae), which creeps over the Char a and submerged wood.
It (Fig. 93) has a case made of the minutest sand grains and pieces of
humus, such as are stirred up by the waves and which are to be found

Representatives of a Young Pond Community

Fig. 86. — The shell of a mussel (Anodonta grandis footiana) that has been broken
open by a muskrat; slightly enlarged.

Fig. 87. — The burrowing dragon-fly nymph (Gomphus spicatus), with the mask
extended.

Fig. 88. — Some fishes of the pond. The dark fish which rests near the bottom is
the mud minnow (Umbra limi). The fish swimming about is the golden shiner
(Abramis crysoleucas) ; 1/5 natural size.

among the chara. This species is the successor of the bottom species
(Goer a). It belongs to a different group and has structural characters
which distinguish it from Goera, but which probably have no relation
to its habitat or habits. On the other hand, the mores as indicated by
case-building is also different but is related to the environment. The

144

POND COMMUNITIES

crustaceans constitute an important element in this association. The
smaller amphipod (Hyalella knickerbockeri) is abundant among the
chara. The crayfish (Cambarus immunis) occurs here sparingly. In
ponds there is an important element of small crustaceans that belong
to the vegetation and the bottom; this element is composed chiefly of

Representatives of the Submerged Vegetation Association

Figs. 89, 90, 91. — Larva of a midge (89), pupa of the same (90), the adult.
Midges are inhabitants of the chara-covered bottom; enlarged about 4 times (after
Johannsen, Bull. N.Y. State Museum).

Fig. 92. — The eggs of the common large black horsefly on the tip of the bulrush

stalk.

Fig. 93. — The chara-inhabiting caddis-worm (Leptocerinae); enlarged as indi-
cated.

Fig. 94. — Ostracod (Notodromas monacha Miill.); 30 times natural size (after
Sharp) .

Ostracoda (Fig. 94), which are small bivalved forms resembling the
bivalved Mollusca. They form food for fishes to a small degree.

Especially abundant just under the chara are the red water-mites
(Limnochares aquaticus) (Fig. 80, p. 130). One sees numbers of these

PIONEER COMMUNITIES 145

when he stirs the bottom. Creeping over the plants are the small
snails (Amnicola limosa) (Fig. 100, p. 146). These respire by means
of gills. Other snails are also occasionally present. Physa and Lym-
naea, etc., are always small or juvenile. We have never taken an adult
specimen of these from the young ponds and in all only a few specimens
have been taken. These animals get into the ponds that are formed by
the removal of sand. We are not at all sure but that the few forms
found in Pond 1 are the result of such entrance, rather than the regular
establishment of the species.

Among the bulrushes are a few aquatic insects that belong to the
vegetation that comes above the surface. One of the most characteristic
forms is the neuropterous larva (Chauliodes rastricomis) (Figs, no,
in, p. 150), which is a marsh form and will drown in water.

Characters of the association: This association differs from the
preceding and from the others generally in being distinctly aquatic and
also essentially independent of the bare bottom and of the surface. The
animals of this association are, however, strictly dependent upon the
vegetation for nesting-places, shelter, etc. The mud minnow has been
studied experimentally and shows avoidance of direct light.

Tendencies in the association: This association, like all the others, is
destined not to last; changes are taking place all the time. The chara
is filling the pond at the rate of one inch a year (58) and is making a fine
soil for roots of other plants. As soon as the dense chara stage has
existed for a time we find other plants, such as Myriophyllum, Pota-
mogeton, and water-lilies. As soon as these have become established we
have the commencement of the next association. These plants usually
appear in spots, and in many cases the zones are much less important
than in the lakes because of the small areas of the plants. We can,
however, recognize a zone of water-lilies, and zones or patches of other
plants.

Just as we noted that the formations of the bare-bottom type existed
in the small ponds with the Chara, we see also that the surface-reaching
vegetation occurs with the Chara association and often all three occur
together. Pond 5 contains a poorly developed phase of all three, the
bare bottom being of minor importance. Pond 7 contains the chara
association and the surface-reaching association. Ponds 14 and 30 are
the best expressions of the surface-reaching type, and Pond 52 is
the last stage of it. This will be discussed more fully, and we will
pass directly to the association of the vegetation which reaches the
surface.

146

POND COMMUNITIES

4. THE ASSOCIATION OF EMERGING VEGETATION

(Stations $4~37, 39> Ponds 5, 7, and 14) (Fig. 101) (30 and 52)
With the incoming of the water-lilies and the fine-leafed plants, we
have the inauguration of a new state of affairs. Among the new animals

1

! a

c

99-/-. - A-

Representatives of the Dense Bulrush Association (Pond 5)
(All about natural size)

Fig. 95. — The common diving spider (Dolomedes sexpunctatus) . The individual
from which this drawing was made was taken with a nymph of the dragonfly shown,
in its jaws.

Figs. 96, 97, 98. — Various stages of a dragon-fly (Leucorhinia Intacta) : 96, nymph;
97, about to shed its outer covering; 98, the adult. (Modified from Needham.)

Fig. 99. — The larva of a caddis- worm (Phryganeidae) , which makes its case from
bits of grass blades, etc.

Fig. 100. — Small gill-breathing snail (Amnicola limosa).

that come in, the bivalved mollusks deserve special mention. The
Unionidae must have bare bottom for their activities; they are too large
and heavy to climb on such small vegetation, and the development of
such a habit has not taken place. They disappear with the sparse

MATURE COMMUNITIES

147

Char a. Their place is taken by other bivalves, viz., the Sphaeridae, such
as Musculium partumeium, which lives in the humus of the bottom, and
Musculium secure and trmicatum, which live in the vegetation and are
able to climb on the vegetation and on the side of aquarium jars.

In the early phases, shrubs and young trees have begun to grow by the
sides of the ponds and these from time to time fall into the water, thus
forming a resting-place for many forms that are not found in the other
situations. Diving spiders (Fig. 95) are common on the bulrushes which

Fig. ioi. — Showing Pond 14 at moderate low water. In contrast with Pond 1
we see that it is choked with emerging vegetation and the margin occupied by shrubs
and bulrushes, etc.

are here growing on a bottom of humus outside leaf-bearing plants
(Fig. 101), inside the shrubs. These spiders dive for the immature
aquatic insects which are here at their maximum. We find numerous
damsel-fly nymphs and dragon-fly nymphs, both the creeping form (Leu-
corhinia intacta) (Figs. 96, 97, 98) and the climbing form. The burrow-
ing dragon-fly nymph has gone, or is present in small numbers only, and
there are but few May-fly nymphs. Those that persist creep about on
submerged sticks in company with Amnicola and are especially likely to
occur in the earlier phases of this community. With these occur the

148 POND COMMUNITIES

caddis-worms (Phryganeidae: Neuronia) (Fig. 99), which are also abun-
dant in the later stages of dense vegetation. This worm's case is some-
what similar in form to that of Leptoceridae, being a circular tube, but it
is made of pieces of grass blades or other pieces of plant fragments instead
of sand grains. The pieces are fastened together with silk. The worm is
found creeping among the vegetation, drawing its case after it. Amnicola
(Fig. 100), the river-dwelling snail, is common, especially on twigs and
logs. In the mature stage represented by Pond 14 (Fig. 10 1) the com-
mon newt (Fig. 102) probably reaches its maximum abundance. The
snails which are at best advantage in these ponds are the lung breathers.
They can here come to the surface for air, and food is abundant, as the
surfaces of the plants are covered with algae and these form the food of
the snails. Those snails which come to the surface for air are common.
Planorbis campanulatus (Fig. 103) is characteristic of the mature stage
and Lymnaea refiexa (Fig. 104) in the older stages. The individuals in
this case are larger than those of the temporary marshes (cf. Figs. 104
and 125, pp. 149, 175). Planorbis parvus (Fig. 105) is commonest in the
earliest phases and Planorbis hirsutus (Fig. 106) in the later. Diving
beetles (Fig. 107), which are common throughout, are most numerous
in the denser vegetation. The soldier-fly larvae (Fig. 108) are often
common in the dense filamentous algae of the mature phases of the asso-
ciation; here the number of all dipterous larvae is greater than at any
other point. Midge larvae occur in great numbers, having their cases
among the algae. Horseflies (Fig. 92), also T any pus, Ceratopogon, and
some mosquitoes are present. Specific identification, however, is not
possible, and whether or not the species differ in modes of life or reactions
from those inhabiting the earlier stages in the pond series has not been
determined.

Adult aquatic insects have increased with the increase in vegetation,
in a remarkable fashion. The prominent forms are the larger bugs, such
as the electric-light bugs (Zaitha fluminea and Belostoma americana
Leidy, with Benacus griseus Say). The water-boatmen are also common.
The species of these are not well known, and we cannot say whether or
not they are the same in the older and younger ponds. Back-swimmers
are also abundant {Notonecta variabilis and undulata, Buenoa platycnemis,
and the small form, Plea striola, occur here). They are few in number
or absent from the younger ponds.

Some animals particularly abundant in the older stage are the
common leech {Placobdella parasitica) (Fig. 109), the larvae of a netted-
winged insect (Chauliodes rastricornis) (Figs, no, in), the large flat

MATURE COMMUNITIES

149

snail {Planorbis trivolvis) (Fig. 112), and the amphipod (Eucrangonyx
gracilis) (Fig. 113). All these occur in the senescent stage, where in
dry years the pond goes almost dry. The vertebrates of the mature
and later stages are not numerous. The fish are limited to mud- and
muck-preferring species, the black bullhead (Ameiurus melas) and the
mud minnow {Umbra limi) (106). The grass pickerel and the dogfish
are found in such vegetation-choked ponds.

05

04 ^106""*

Representatives of the Emerging Vegetation Association (Pond 14)

Fig. 102. — The common newt (Diemictylus viridescens); natural size (after Hay).

Fig. 103. — A flat pond snail (Planorbis campanulatus); natural size.

Fig. 104. — The common pond snail (Lymnaea reflexa) ; natural size.

Fig. 105. — Small flat snail (Planorbis parvus); 3 times natural size.

Fig. 106. — A snail (Planorbis hirsutus); 3 times natural size.

Fig. 107. — A predaceous diving beetle (Cybister fimbriolatus Say) ; natural size.

Fig. 108. — A soldier-fly larva — unidentified; twice natural size.

The amphibia are the frogs which occur in all stages of the associa-
tion, and the common salamander {Ambly stoma tigrinum), which burrows
in the soft mud where it remains during the greater part of the year.
It comes out in spring (February or March) and deposits eggs in the
pond, where the young are found later. Of the turtles the common

i5o

POND COMMUNITIES

painted turtle {Chrysemys marginata) is abundant, basking on the fallen
trees. The geographic turtle and the snapping turtle are found also
in the younger phases. Garter-snakes pick up their food along the
ponds (Fig. 114), while muskrats, occasional minks, and various aquatic
birds (108) feed in the ponds.

Senescent Pond Inhabitants

Fig. 109. — A leech with young attached to the ventral side (Placobdella para-
sitica) ; natural size.

Fig. 1 10. — The larva of a netted-winged insect (Chauliodcs rastricomis).

Fig. hi. — Pupa of the same (slightly enlarged).

Fig. 112. — A snail {Planorbis trivolvis); natural size.

Fig. 113. — Common amphipod (Eucrangonyx gracilis) ; twice natural size.

Fig. 114. — Pond 58 in a dry season, showing dead fish (mud minnows) both
on bottom and out of water and in the water. A garter-snake (Thamnophis sp.)
feeding on the fish.

Consocies of logs. — This is the chief place to find the sponge and the
polyzoa. Their numbers vary from year to year but they are usually

SUCCESSION OF COMMUNITIES 1 51

present. With them are often found leeches, especially Macrobdella
decora, which is a brilliant red-and-green form. The only character-
istic insect is the dytiscid beetle (Agabus semipunctatus Kirby) (99c),
a slender reddish-brown form. The other forms found here are inci-
dental in the vegetation. Hollow logs are probably used for breeding-
places by the fishes, such as the bullheads (105), while the eggs of Physa
and of water-mites, and some of the aquatic insects, are also placed here.
The mammals of these ponds are the muskrat, which occurs in all the
stages, and the mink, which is now rare.

Tendencies of the association: This association is unstable. Its
fate is heralded by the incoming of different amphibious plants at the
sides. This is the form Proserpinaca, with the divided leaves above
water and the entire ones below. This is often associated with Equisetum
and plants that have the growth form of grasses. Following these are
the shrubs, such as the buttonbush (6). Before these have captured
the entire pond it becomes dry during the dry season and the end of the
aquatic community is come. The formation which follows is the tempo-
rary pond, swamp, or marsh type.

Characters of the formation : The formation composed of the two
associations mentioned may be characterized as made up of forms
which require but little oxygen, and no bare bottom. The reproduction
is one of two types : either the young are carried or the eggs are attached
to plants. Some of those carrying the young are the Sphaeridae, the
amphipods, and the isopods. Those sticking the eggs onto or into the
vegetation are the snails (all), the Dytiscidae, all the species recorded, the
Hydrophilidae, the Notonedidae, the Belostomidae, the Ranatras, the
caddis-flies, the Donacias, and in fact most of the forms of the formation.

IV. Succession

The first formation to take possession of a pond when it is first
separated from a lake like Lake Michigan is the bare-bottom formation ;
chara soon makes its appearance in the deeper parts and we have the
beginning of the chara association. The chara association so acts upon
the bottom by covering it with humus and vegetation that it renders
the continued existence of the bare-bottom formation impossible (6,
112, 114, 114a). At the same time it prepares a way for the vegetation
which reaches to and above the surface. This, in turn, fills the pond
still further, and the strictly marsh vegetation takes possession. The
history of the true pond is then at an end and the story of the marsh
begins. Our series of 95 ponds illustrates the series of stages. The

I5 2 POND COMMUNITIES

vegetation which comes to the surface of the water and the later marsh
and swamp vegetation encroach from the sides toward the center.

Entomostraca do not ordinarily show so clear a succession of species
as do other groups and our collections are very incomplete. The follow-
ing have been noted: Cladocerans: Ceriodaphnia reticulata Jurine, C.
pulchella Sars, and C. quadrangula Muel. from Ponds 52 to 93.
Copepods: Cyclops albidus Jurine appears more common throughout
the series and C. viridis Jurine is common in the older ones. Diaptomus
reighardi Marsh is in the younger ponds and its place is taken by
D. leptopus Forbes beginning with Pond 30. Of the ostracods, Cypria
exsculpta Fisch. is common throughout the series. Cypridopsis vidua
Mull, is common in the semi-temporary ponds.

I. FATE OF THE PONDS

In the late stages the pond dries during extreme droughts and passes
rapidly from the stage at which it dries occasionally during a dry season
to the stage when it dries every season. It is then known as a marsh or
swamp, or often vernal marsh or swamp, or summer dry pond. At such
a stage it is a land habitat in summer and a water habitat in spring. As
the pond bottom is built up higher by the accumulation of peat, and the
surrounding ground-water level is lowered by the forces of erosion, the
question of what is to become of the pond brings us to a question of great
importance in connection with climatic formations. It will become what-
ever the surrounding climatic formation may be. If it is forest, directly
or indirectly, the pond becomes forest, and if it is steppe the pond be-
comes steppe, while if prairie or savanna the pond becomes savanna.

We have already noticed that the area of study is on the border of
the forest and prairie (steppe formations). A pond in the area of study
may therefore become prairie or forest. Ponds with sloping sides usually
become prairie, and those with steep abrupt banks or shores turn into
forest. There is no marked difference between the animal life of the two.
Collections made in a series of three prairie ponds which are situated
near Wolf Lake, Ind., and which in ecological age may be compared with
Ponds 1,7, and 14 of the Lake Michigan series, are almost parallel with
the collections from the Lake Michigan ponds. The differences to be
noted are that the snail Planorbis trivolvis, which usually occurs in old
ponds only, is found in the earliest pond of the prairie pond series, while
the snail Vivipara contectoides and the shrimp Palaemonetes paludosus,
which usually occur only in streams and small lakes, also occur in the
prairie pond series. The presence of the latter two may be explained, how-
ever, by the fact that the ponds were once connected with Wolf Lake.

POND ANIMALS

153

In the pond formation proper, the fate of the pond early becomes
evident along the margin. This will be discussed in connection with
swamps and marshes. The discussion of the areas properly called
marshes and swamps is the most complex of all our discussions, and will
be taken up in the chapter on swamps, marshes, and temporary ponds.

Tables XXVII-XXXIII show animals recorded from the series of
ponds at the head of Lake Michigan (Stations 32-37).

TABLE XXVII

Sponges

Name

Pond Numbers

1

5

7

14

30

52

93

95

Meyenia{?) crateriformis Pot.. . .

Meyenia fluviatilis Auct

Heteromeyenia argyrosperma Pot .
Spongilla fragilis Leidy

*

*

*
*
*

*

TABLE XXVIII

Leeches

Name

Pond Numbers

1

Sc

ya

M

3°

52

93

95

Glossiphonia fusca Castle

*
*
*

*
*
*
*

*
*
*
*
*
*

*

*
*
*
*

*

*
*

*

*
?

*

*
*
*

Dina fervida Verrill

Erpobdella punctata Leidy

M acrobdella decora Say

Haemopis grandis Verrill

Placobdella parasitica Say

Placobdella rugosa Verrill

Glossiphonia heteroclita Linn

Haemopis marmoratis Say

TABLE XXIX

Sphaeridae and Unionidae

Pond Numbers

Name

1

5^

7a

146

3°

52

93

95

Unionidae —
Lampsilis luteola Lam

*
*
*

*
*
*

*

*
*

*

*

?
*

*
*

?

*

*

*

A nodonta marginata Say

A nodonta grandis footiana Lea . . .
Sphaeridae —

Musculium truncatum Lins

Musculium secure Prime

Musculium partumeium Say

154

POND COMMUNITIES

TABLE XXX

Snails

Name

Pond Numbers

i

SC

7a

14&

30

52

Q3

OS

Amnicola —

Amnicola limosa Say

*
*

F

*

*
*
*
*
*

F

*
*

F

F

*

*

*

*

F

*
*
*

c

*
*
*
*
*

c

*

*
*

*

c

*

*
*
*

A

C

*

c

*

A

A

?

*
*

*
*

*
*

*
*

Amnicola Cincinnati ensis Lea. . . .

A mnicola limosa parva Lea

Physa—

Physa gvrina Say

Physa hcterostropha ? Say

Lymnaeidae —

Lymnaea reflexa exilis Lea

Planorbis bicarinatus Say

Lymnaea kumilis modicella Say . .

Planorbis parvus Say

Planorbis campanulatus Say

Planorbis hirsutus Gld

Planorbis exactions Say

Lymnaea reflexa Say

Planorbis dcflectus Say

Planorbis trivolvis Say

Segmentina armigera Say

?

TABLE XXXI

Crustacea

Pond Numbers

Name

1

5c

7 a

146

30

52

93

95

Hyalella knickerbockcri Bate

Eucrangonyx gracilis Smith

Mancasellus danielsi Rich

Asellus communis Say

Cambarus immunis Hagen

Cambarus blandingi acutus Girard . .

c

F

c

F
F

c
c

c

F

F
A

C

F

F

A

*

*

C

?

A

*

*
*
*

A

*

*
*

F

*
*

POND ANIMALS

155

TABLE XXXII

Aquatic Insect Larvae and Nymphs

Name

Pond Numbers

14&

30

*

*

*

*

*

*

*

*

*

*

*

*

?

*

c

A

*

*

*

*

*

*

?

*

?

?

*

*

*

c

?

*

*

93

May- flies —

Siphlurus sp

Caenis sp

Callibaetis sp

Neuroptera —

Chauliodes rastricornis Ram . ,
Damsel-flies —

Lestes sp

Enallagma sp

Ischnura verticalis Say

Dragon-flies —

Tramea lacerata Hagen

Celithemis eponina Drury. . . .

Libellula pulchellaDrury

Gomphus spicatus Selys

Leucorhinia intacta Hagen . . .

Anax Junius Drury

Sympetrum rubicundulum Say

Sympetrum sp

Pachydiplax longipennis Burm

Epiaeschna heros Fab

Caddis-worms —

Goera sp

Leptocerinae sp

Neuronia sp

Diptera larvae —

Chironomid larvae

Stratiomyid larvae

Tanypus sp

Tipulid larvae

Ceratopogon sp

Hemiptera — ■

Ranatra kirkaldyi Buen

Corixa sp

Ranatra fusca P.B

Zaitha fluminea Say

Notonecta undulata Say

Buenoa platycnemis Fieb

Notonecta variabilis Fieb ,

Plea striola Fieb

Water-striders —

Gerris rufoscutellatus Lat

Gerris marginatus Say

Mesovelia bisignata Uhl

156

POND COMMUNITIES

TABLE XXXIII
Distribution of Fish: Ponds Arranged According to Ecological Age
For meaning of numbers and letters see Fig. 84, p. 139.

Common Name

Large-mouthed black bass

Bluegill

Blue-spotted sunfish

Pumpkin-seed

Warmouth bass

Yellow perch

Chub-sucker

Spotted bullhead

Pickerel

Mud minnow

Golden shiner

Yellow bullhead

Black bullhead

Dogfish

Scientific Name

Micropterus salmoides .

Lepomis pallidas

Lepomis cyanellus ....
Eupomotis gibbosus . . .
Chaenobryttus gulosus .

Perca flavescens

Erimyzon sucetta

Ameiurus nebulosus . . .

Esox vermiculatus

Umbra limi

Abramis crysoleucas. . .

Ameiurus natalis

Ameiurus melas

Amia calva (juvenile) .

Ponds

14J

TABLE XXXIV

Higher Vertebrates

Name

Pond Numbers

14ft

Aromochelys odorata Lat . . .

Rana pipiens Sch

Chrysemys marginata Ag . . .
Graptemys geographicus LeS
Diemictylus viridescens Raf .
Fiber zibethicus Linn

CHAPTER IX

CONDITIONS OF EXISTENCE OF LAND ANIMALS

I. Introduction

Man being a land animal, it is natural that he should be more familiar
with the conditions of existence of land animals than with those of aquatic
forms. The reader will recognize that the primary divisions into which
land animals may be divided are (a) those living exposed to the atmos-
phere on the surface of the soil and of plants and animals, and (b) those
out of direct contact with the atmosphere, in the soil, in wood, and in the
tissues of living plants and animals. The solid substances in and upon
which animals live are called materials for abode (55, 115) and, aside from
soil, materials are just as varied as are the living and decaying bodies of
plants and animals. For this reason, an adequate discussion of such
materials for abode would require a separate treatise. Since the laws
governing the physical conditions surrounding animals living hidden
away, for example in the bodies of living and dead organisms, are little
known, we will pass directly to a discussion of the conditions of existence
of animals living in soil and exposed to atmosphere.

II. Soil (116)

Because of its importance in agriculture, the relation of plants to soils
has been much studied. The laws governing plants in their relation
to soils apply in the main to soil-inhabiting animals, all the various
properties of soils being of some importance in this connection.

1. TEXTURE

The texture of soils is of importance to animals because of the vary-
ing difficulty with which they may burrow into it, and the ease with
which their burrows are maintained when once dug. Particular animals
prefer soils of a particular texture, some preferring rock, some sand, etc.

2. WATER

Most subterranean animals are submerged in water during rains.
The amount of water which they encounter in the soil at other times is
determined to a large extent by their relation to the water table (57), and
by the character of the soil. The water-holding power of different soils
is different. It increases with the decrease in size of the soil particles and

157

158 TERRESTRIAL CONDITIONS

with the addition of humus which takes up water by imbibition. The
amount of water in the soil is usually expressed in terms of per cent of
weight, but a soil with 8 per cent of moisture may not give up water to an
organism as readily as another soil with only 2 per cent. It is necessary
therefore to determine the capacity of a soil to retain or give up moisture.
This has been determined for a number of soils (117, 118), in terms of
what is called the moisture equivalent. The moisture equivalent of a
soil is the percentage of water which it can retain in opposition to a cen-
trifugal force 1,000 times that of gravity. The maintenance of turgor
in plants is believed to be a purely physical matter. If the roots of a
plant are in a mass of soil, the plant gradually reduces the water content
until the permanent wilting occurs. The wilting coefficient of a soil is
the moisture content (in percentage of dry weight) at the time when the
leaves of the plant growing in the soils first undergo a permanent reduc-
tion in moisture content, as a result of a deficiency of moisture supply.
The moisture equivalent of a soil is 1 . 84 times the wilting coefficient for
wheat, used as a standard plant. Fuller (119) states that the wilting
coefficient of dune sand is about o. 75 per cent, while the usual moisture
content of the cottonwood dune sand is two or three times this amount.
For the clay soil of the oak-hickory forest, according to McNutt and
Fuller (1 19a), the coefficient is about 8 per cent. These standards of soil
moisture indicate the amount of water available to animals through
direct contact with the soil or available for evaporation into the air of
cavities which they construct for themselves beneath the surface of the
soil. A soil gives water to or takes water from the body of a subter-
ranean animal in proportion to the availability of water in the soil in
question. The amount of available water increases with depth (119).

3. TEMPERATURE

Transeau found that the temperature of bog soil and bog water is
below that of other soils and waters. This has, however, not been
observed for different dry soils. The differences between soil on the
beach at Sawyer, Mich., August 19, 1911, at 3:00 p.m. and in the beech
woods near at hand was as follows: Air 20 C, upper half-inch of beach
sand 38°-39° C, sandy soil of beech woods i<f-2o° C, a difference of
1 9 C. The upper half -inch of bare sand goes as high as 47 C. on the
hottest days of summer, while the soil in the beech woods is probably
always a little cooler than the air at the time of the air maximum.
Dune sand temperature on the hottest summer days at about 3:00 p.m.
has been found to be as follows:

ATMOSPHERE 159

TABLE XXXV

Showing Variation of Sand Temperature with Depth and Moisture Content

Air 36 C.

Moist Sand

i . 25 cm. below surface ,

3-4 cm. below surface ,

8-9 cm. below surface ,

io-ii cm. below surface,

12-13 cm - below surface,

17-18 cm. below surface,

32° C.
3i° C.
29 C.

27 C.

It will be noted from the table that temperature decreases with depth
and with increasing moisture.

4. PLANTS AND ANIMALS

Cowles (120) mentions the importance of soil bacteria which increase
with the increase of the humus, and the development of substances toxic
to the plants producing them(i2i,n 4a) . Little is known of the effect of
animals upon the soils in which they live but if excretory products ever
accumulate in any quantity, they probably have a detrimental effect,
especially upon the animals which produce them (114). On the other
hand, many burrowing animals bury organic material and bring mineral
soil to the surface. The digger wasps add much to the sand by burying
many insects for their young. Earthworms contribute to soil forma-
tion (30). Cowles states further on the authority of Transeau (122) that
humus accumulation alters soil aeration. It follows that the atmosphere
available to subterranean animals differs in different soils.

III. Atmosphere

Animals living fully exposed to the atmosphere are usually those most
dependent upon the various physical factors of the air, viz., light,
temperature, pressure, humidity, currents, electrical conditions, etc.

I. LIGHT

Animals are either positive or negative to the actinic rays of the
spectrum (45, 123). Considerable work has been done by plant
ecologists, on the measurement of light with photographic papers, but its
bearing on plant problems is questioned by some because the nonactinic
portion of the spectrum is most important in the process of photosyn-
thesis. It appears that these measurements are of much greater signifi-
cance for animals than for plants. Zon and Graves (124) have brought

160 TERRESTRIAL CONDITIONS

together the literature and discussed the methods of study (see especially
several papers by Wiesner). The light in which animals live varies from
that of the strongest sunlight of mid-day to the darkest recess of soil, etc.
Many animals show diurnal migration due to changes in light.

2. TEMPERATURE

The temperature of the air varies with light (insolation). Cloudy
summer days are about 4 cooler than sunny days. Cloudy winter days
are warmer (125, p. 136) than sunny ones. The temperature of the
lowest strata of air on sunny days varies in some inverse ratio with the
distance from the soil, vegetation, etc. The temperature immediately
above bare soil may be very high in summer (see Table XXXV).

3. PRESSURE

According to experimental work by Cohnheim and others (126, 127),
man is sensitive to variations in atmospheric pressure. Many other
animals, such as rabbits, dogs, etc., are probably also sensitive. Bird
movements are often correlated with variation in atmospheric pressure.
In all cases the pressure, as meteorologically recorded, represents a
variation in humidity, etc., and relations to pressure alone have been
but little studied.

4. HUMIDITY

Atmospheric humidity (128) is very important to animals and
determines the sensible temperature and rate of evaporation to a large
degree (see under " Evaporation," below).

5. COMPOSITION OF THE ATMOSPHERE

(Table II, p. 59)
The amount of carbon dioxide varies (125) in different localities but
is usually greatest near the ground where decomposition is taking place.
Animals living among decaying organic substances probably live in the
presence of much more carbon dioxide than animals upon vegetation.
Carbon dioxide is probably important to animals because of its effect
upon respiratory activity. Carbon dioxide is believed by some physiolo-
gists to be a necessary stimulus to the brain to cause all respiratory
movements. It is further held by some that mountain sickness (asso-
ciated with high altitude) is due to decreased carbon dioxide pressure.

6. CURRENTS
Currents of wind are important in scattering animals and in affecting
the rate of evaporation from their bodies. Some animals take up

ATMOSPHERE 161

definite positions with reference to wind (anemotaxis) (128a), as for
example some flies hover in the air in one position with the head toward
the wind. Some animals, such as the land salamanders, frogs, toads,
millipedes, spiders, and insects turn away from currents of air because
of increased evaporation.

7. ATMOSPHERIC ELECTRICITY (125)

The effect of atmospheric electricity upon organisms is little known.
It varies with variations in other conditions of the atmosphere. It will
probably be found to be important in the life of animals.

IV. Combinations or Complexes of Factors

As has already been pointed out (55), the animal environment is a
combination of moisture, temperature, light, pressure, materials for abode
and food, all of which factors taken together constitute a complex of
interdependences. These various factors are so dependent upon one
another that any change in one usually affects several others. This
property of environmental complexes is what makes ecology one of the
most complex of sciences, and experimentation in which the environment
is kept normal except for one factor, an ideal rarely realized in practice,
even under the best conditions.

The efforts of ecologists, geographers, and climatologists have long
been directed toward the finding of a method of measuring the environ-
ment which shall include a number of the most important environ-
mental factors. De Candolle undertook to base the efficiency of a
climate, for supporting plants, upon the mean daily temperatures above
6° C, this temperature being taken as the starting-point of plant activity .
Merriam has followed this lead and calculated total temperatures for
many places in North America and made maps and zones based upon
such totals. This system, however, has been rejected by botanists and
plant ecologists on account of much evidence, both experimental and
observational, which is quite out of accord with this view. The scheme
has not been generally accepted by zoologists outside of the United States
Biological Survey. There is practically no evidence of an experimental
sort for the application of such a scheme to animals. Relative humidity
has been suggested as an important index (128) but does not properly
express the influence of atmospheric humidity upon the animal body
(125, p. 53). The saturation deficit has also been suggested but does
not take temperature into account.

162 TERRESTRIAL CONDITIONS

I. EVAPORATION

"The total effect of air temperature, pressure, relative humidity,
and average wind velocity upon a free water surface in the shade or in
the sun is expressed by the amount of water evaporated" (125, p. 72).
Since temperature in the season without frost is directly due to the sun's
rays, light is in part included. In our latitude, clouds in summer slightly
decrease the air temperature (125, p. 72). In winter, however, the
temperature of cloudy days is higher. The strongest light is usually
associated with the greatest evaporation. Yapp (129) found that the
rate of evaporation was directly correlated with temperature and illumi-
nation, but most closely correlated with relative humidity. From the
standpoint of including many factors, the evaporating power of the air is
by far the most inclusive and is therefore by far the best index of physical
conditions surrounding animals wholly or partly exposed to the atmos-
phere. It is not, however, to be expected that it will hold good for all the
factors under all climatic conditions, and for this reason, records of light,
temperature, pressure, carbon dioxide, etc., should be made.

The data are usually obtained by using a porous cup atmometer.
Evaporation from the atmometer is more nearly like that from an organ-
ism than is evaporation from any other device; it was devised by
Livingston (130). "It consists of a hollow cup of porous clay 12.5 cm.
high, with an internal diameter of 2 . 5 cm. and a thickness of wall of about
3 mm. It is filled with pure water and connected by means of glass
tubing to a reservoir usually consisting of a wide-mouthed glass bottle of
one-half liter capacity. The water, passing through the porous walls,
evaporates from the surface, the loss being constantly replaced from the
supply within the reservoir. Readings are made by refilling the reservoir
from a graduated burette to a certain mark scratched upon its neck.
For convenience in handling, a portion of the base of the cup is coated
with some impervious substance and, before being used in the field, the
instrument is standardized by comparing its loss of water with that from
a free water surface of 45 sq. cm. exposed under uniform conditions. As
a further check against error this standardization is repeated at intervals
of six to eight weeks throughout the season'' (Fuller, 131). In Fuller's
work, the bottles were arranged so that the evaporating surface of the
instrument was 20-25 cm - above the surface of the soil.

a) Effect of evaporation upon animals. — In the case of man some
observations have been made. According to Pettenkoffer and Voit (fide
125), an adult man eliminates 900 gms. of water from his skin and lungs

EVAPORATION 163

daily. Of this amount 60 per cent or 540 gms. come from the skin alone
and changes in relative humidity of only 1 per cent cause perceptible
changes in the amount of evaporation from the skin. If evaporation
from the skin and lungs is diminished, the amount of urine is increased,
as in many cases are also the secretions of the intestines. Sudden
changes in humidity make themselves felt in sudden increased or
decreased blood pressure. The less dilute blood of dry climates operates
as a stimulant and increases the functions of the nervous system. The
consequences are excitement and sleeplessness (125, pp. 56-57).

Little has been done on the physiological effect of evaporation or
desiccation upon cold-blooded animals. Various writers have found a
loss of water associated with hibernation. Greeley (132) obtained the
same results with desiccation as with freezing (132; 133; 51, pp.
182-88). The reactions of animals to evaporation gradients have been
studied by the writer (134). A high rate of evaporation is advanta-
geous to some animals and decidedly detrimental to others. Animals
inhabiting dense woods turn back when they encounter air with a high
evaporating power. This is true of frogs, salamanders, insects, and
millipedes. The frogs and salamanders die in an hour or more in an
atmosphere of high evaporation power but centipedes and ground beetles
and other heavily armored animals do not die for many hours or even
days though they react negatively to the dry air when they encounter
it in a gradient. Animals from hot, dry, sand areas usually select air of
high evaporating power and die in air of high evaporating power only
after very long exposure. The results of a long series of experiments
may be summarized as follows: (1) the animals studied react to air of
a given high rate of evaporation whether the evaporation is due to
moisture, temperature, or rate of movement; (2) the sign and degree
of reaction to the given rate of evaporation are in accord with the com-
parative rates of evaporation in the habitats from which the animals
were collected; (3) the animals of a given habitat are in general agree-
ment in the matter of sign and degree of reaction; the minor differences
which occur are related to vertical conditions (see below) and kind of
integument; (4) there is a rough agreement between survival time in air
of high evaporating power, and kind of integument, but no agreement
between survival time and habitat when a number of members of a com-
munity are taken together. The relation of warm-blooded animals to
rate of evaporation has been sufficiently studied so that, when it is
taken with the work on cold-blooded animals, we are warranted in con-

1 64

TERRESTRIAL CONDITIONS

eluding that the evaporating power of the air is probably the best index
of environmental conditions of land animals.

b) Evaporation in different habitats. — The evaporating power of the
air varies in different situations (Fig. 115). There are great differences
between open prairies and closed forests. Shimek (135) found that the
evaporation in the undisturbed groves in Eastern Iowa during July and
August was very much less than that in the prairies adjoining. From
the free surfaces of pans set in the ground so that the water which
they contained was level with the surface of the soil, the evaporation
of the groves was about 27 per cent of that of the prairie; with
cup evaporimeters about 37 per cent, and with Piche evaporimeters

Per cent, of standard

1. Salt marsh, outer margin...

2. Open gravel slide

3. Carnegie garden, standard. . .

4. Upper beach

5. Salt marsh, inner margin. . . .

6. Garden, high level

7. Gravel slide, partly invaded.

8. Open forest

9. Fresh-water marsh

10. Typical mesophytic forest . . .

11. Ravine forest

12. Swamp forest

Fig. 115. — Showing the comparative evaporation rates in the ground stratum of
several animal habitats on Long Island during July and August (after Transeau,
courtesy of the Botanical Gazette).

20

40

60

80

100

120

m

about 47 per cent. This is about the same as the difference on Long
Island between the inner side of Transeau 's salt marsh dominated
by grasslike plants and his mesophytic forest. Sherff (135) found the
evaporation in a marsh forest to be a little less than that in the beech-
maple and from 1.8 to 2.6 times as great as in the lowest stratum of
an open marsh.

c) Vertical differences in evaporating power and other conditions. — The
evaporating power of the air is usually greater at the higher levels of a
habitat.

STRATIFICATION

165

TABLE XXXVI

Evaporation from Porous Cup Evaporimeters in Different Strata of a
Summer Dry Marsh, Cambridgeshire, England, during Three
Periods between July 9 and September 8, 1907
(Yapp, 129, p. 299)

Ratio of
Evapora-
tion

Temperature

Height above
Ground

Mean
Max.

Mean
Min.

Mean

5 ft. 6 in. to 4 ft. 6 in. .
2 ft. 2 in

100.00

32.8

6.6

22. 1
23.O

18.O

12. 7

6.6

11 . 2

16.5
14. 1

11. 8

Well above vegetation

A little above the mid-height

5 in

Soil

Table XXXVI shows marked differences in the rate of evaporation
and considerable differences in temperature at the different levels, both
due largely to vegetation. Differences in light are also to be expected.
Sherff (136, p. 420) has found conditions similar to the above by a two
months' study of evaporation on Skokie Marsh near Chicago. The
evaporation there was three times as great at a height of 1.95 m. as at
the surface of the soil in among the plants of Phragmites. Mr. Harvey
has secured similar (unpublished) results on the prairie at Chicago
Lawn, Chicago, also Mr. Fuller, in the beech woods.

Division into strata: Plant and animal habitats are commonly
divided into strata as shown below.

Plant (12) after Warming
1. No such stratum recognized.

2. Ground stratum made up of algae,
mosses, immediately above the sur-
face of the ground.

3. Field stratum; grasses and herbs.

4. Shrub stratum; formed of shrubs
taller than the herbaceous vege-
tation.

5. Tree stratum.

Animal

1. Sub-aqueous stratum made up of
animals requiring water during
their active reproductive stages.

1 a. Subterranean stratum made up
of animals or stages in the life
histories of animals which inhabit
the ground, especially during the
breeding season.

2. Ground stratum made up of ani-
mals or early stages in the life his-
tories of animals, as 1.

3. Field stratum; the inhabitants of
the herbaceous vegetation on land.

4. Shrub stratum; inhabitants of
shrubs.

5. Tree stratum; inhabitants of trees.

166 TERRESTRIAL CONDITIONS

V. Quantity of Life on Land (137)

The quantity of life on land has been but little studied. While it is
evident that some habitats have more animals than others, we have no
exact data. As a rule the number of species is small in pioneer situations.
While the number of individuals in some one or two species may be large,
the grand total is probably not so large as in later stages. In forest
development it appears from naturalistic observations that the number
of both species and total number of individuals increases with age up
to the oak-hickory stage, the maximum being in the oak-hickory stage.
The beech and maple forest is qualitatively and quantitatively poor in
animals. Felt (137) records pest species on the trees of the white-oak,
red-oak, hickory forest as follows : Oak in general, 157; red oak, 1 2 ; white
oak, 31; hickory, 30; wild cherry, 38; hazel, 33; total 401. He records
pests on trees of beech and maple forest as follows: beech, 92; sugar
maple, 19; pawpaw, 5; total, 116.

1. FOOD SUPPLY

The food supply of land animals is in part dependent upon soil. All
the chief principles governing the elementary food substance of plants
and animals in water are given on pp. 65-68. Since all these processes
are dependent upon water (as a solvent) and since soils at all times con-
tain some water (116), the reader will easily apply most of the principles
there stated to the soil problem. There is probably no kind of organic
matter found that is not food for some animals. Some require plants
or their juices, some decayed fruits, some wood, some living animals,
and some carrion. Each stage of its decay, a dead plant or animal is
food for some animal.

Certain animals, usually plant-eaters, reproduce very rapidly and are
preyed upon by many other animals. Mice, aphids, grasshoppers are
examples (26). These form small centers about which many of the
activities of a community rotate. The centers are indicated by the
convergence of lines in Diagram 6.

2. EQUILIBRIUM

The balance in land communities is probably less perfect than in
aquatic communities even under strictly primeval conditions. This is
due to the fact that there are many small (feeding) groups of organisms
centering around each of several rapidly reproducing groups such as
aphids, mice, and grasshoppers. It is accordingly probably possible for
a land community to be out of adjustment in some particular corner

EQUILIBRIUM

167

without the maladjustment being felt as far as in an aquatic com-
munity of corresponding magnitude.

To illustrate the character of land communities in the matter of food
supply and equilibrium we have chosen a number of prairie animals and
constructed them into an arbitrary community. This community is
graphically represented in Diagram 6. The arrows point from the
animal eaten to the animal doing the devouring, many such relations
being shown on the basis of actual published records.

Diagram 6. — Showing the food relations of land animals. Circles and ellipses
inclose groups of organisms which are commonly eaten by the same animals, and
groups eating similar food. Arrows point from the animals eaten to those doing the
eating. For explanation see text.

From the diagram we note that wolves destroy the bison. If for any
reason the wolves increased, they would destroy so many bison that the
bison would decrease because wolves were abundant. The greater
destruction of mice in summer by the numerous wolves would cause a
decrease of mice. Finally, wolves would decrease because of lack of big
game in winter and mice in summer. This would give the bison and
mice an opportunity to recover their former number and the whole
chain of changes would be duplicated and a general equilibrium be

i68

TERRESTRIAL CONDITIONS

re-established. The decrease of mice just noted might, however, cause
the coyote to eat more ground squirrels and thus cause an increase of
insects because of the removal of the ground squirrel as a check upon
their numbers. The numerous checks upon the numbers of insects
would tend to prevent their increasing greatly, but would no doubt
affect the greater part of the community. The reader will be able to

A B C D E F

Diagram 7. — Representing the food relations of the animals of a land community.
The circles represent life histories which come into contact or overlap at the point
where one species feeds upon another. The vertical shafts represent the animals
which feed upon the vegetation (herbivora and phytophaga). The extent to which
the shaft penetrates the community indicates its importance as food of the forms
whose life histories are represented. The letters refer to the vertical lines (shafts)
above them. These lines (shafts) represent the various central groups of Diagram 6
and other comparable groups as follows: A, large herbivores such as the bison;
B, the mice, rats, squirrels, and rabbits; C, vegetation-eating birds; D, boring insects
secured by the woodpeckers; E, the large plant-eating insects; F, the small soft-
bodied insects such as aphids, scales, etc. The animals represented by the shafts are,
figuratively speaking, the propellors which keep the life histories shown above them,
turning.

trace out many such possible fluctuations and equilibrations. The
number of possibilities is great even in an arbitrary community, though
much greater in an actual one.

Diagram 7 is a graphic representation of the relations of life his-
tories in land communities to elementary food substances. The number
of plant- feeders which serve to lock the inorganic substances to the main
part of the community is far greater than in aquatic communities.

CHAPTER X

ANIMAL COMMUNITIES OF THE TENSION LINES BETWEEN LAND

AND WATER

I. Introduction

Margins of bodies of water, swamps and marshes, and temporary
ponds are on the border-line between land and water. Swamps and
marshes are areas occupied by plants whose stems, leaves, and blossoms
are in the air and whose roots are in the water or very moist soil,
throughout the year. Areas covered by grasslike plants are commonly
called marshes, while those covered by trees are called swamps.
Swamps and marshes usually contain water the year round and are
commonly either directly connected with some permanent body of water
or are fed by springs. Others are dry in summer, and possess an active
aquatic fauna only in spring and after heavy rains. Our area, being in
a region of glaciation, represents a portion of one of the great marsh areas
of the world. Geologically speaking, however, these features represent
the positions of lakes and serve to show us the fate of our small lakes
and ponds. Classification of these communities is difficult, but they
may be divided into temporary and permanent swamps and marshes
and into margins of lakes, ponds, and rivers.

II. Communities

I. PERMANENT WATER, SWAMP, AND MARSH COMMUNITIES

a) Lake-margin marsh sub-formation (senescent pond, or emerging
vegetation pond association) (Stations 30, 30a, 31). — About the margins
of lakes and ponds there is often a girdle of bulrushes and cattails (Fig.
116) which has a characteristic animal community. The sub-aquatic
stratum is made up of pond animals and has been considered already in
chap. viii. There are a few characteristic animals which live chiefly
above the water. The diving spider (Dolomedes sexpunctatus) (Fig. 95)
crawls about on the marsh vegetation and dives beneath the water for
prey. The long slender spider (Tetragnatha laboriosa) is common among
the bulrushes (138). At the base of the rushes and sometimes crawling
near the top is the snail (Succinea retusa) (91). Common frogs (Rana
pipiens and clamata Lat.) (Fig. 116) and the cricket-frog (Acris gryllus)
hop about in the water (139).

169

170

WET GROUND COMMUNITIES

There are also a number of insects which live upon the vegetation
and never go into the water. These are the blue and yellow moth
(Scepsis fulvicollis), which is most characteristic, flies which breed in the
water, such as horseflies (Tabanidae) (140), Tetanocera, etc., also midges,
mosquitoes, dragon-flies, damsel-flies, May-flies, etc. These are asso-
ciated with grasshoppers, such as Stenobothrus, Xiphidium, and various

Permanent Water Marsh and Its Inhabitants
Fig. 116. — General view of an open bulrush marsh at Wolf Lake.
Fig. 117. — Similar but closer view of a marsh at Nippersink Lake, showing the

yellow-headed blackbird (Xanthoccphalus xanthocephalus Bonap.) perched on the

bulrushes. Photo by T. C. Stephens.

bugs and beetles which belong to drier places but which alight on the
vegetation above the water. These will be discussed in connection with
low prairie communities.

The birds deserve especial attention (108, 141). The pied billed
grebe, the black tern, and coot are especially aquatic. The grebe
builds a nest from decayed floating rushes; its bottom is usually wet and
the eggs commonly lie in moisture. The black tern builds a nest of

SWAMP COMMUNITIES

171

weeds and trash similarly situated; the coot is less aquatic. The yellow-
head blackbird (Fig. 117), mallard, pintail, American bittern, the least
bittern (Fig. 118), the Florida gallinule (Fig. 119), the long-billed marsh
wren, and sometimes the Virginia, sora, and king rails, and the red-
winged blackbird nest in such situations. These birds build nests,
either woven from grasses or in the form of crude piles of dead vegetation,
each species having its characteristic method.

The muskrat breeds here and builds a nest from bulrushes (Fig. 82,

Permanent Water Marsh and Its Inhabitants

Fig. 118. — Nest of the least bittern (Ardetta exilis Gmel.) in a marsh at Nipper-
sink Lake. Photo by T. C. Stephens.

Fig. 119. — Nest of the Florida gallinule {Gallinula galeata Licht) in a marsh at
Nippersink Lake. Photo by T. C. Stephens.

p. 131). The mink likewise is found in this kind of situation (22, 142,
143). The grassy outer edges of such ponds are the favorite breeding-
places of frogs (Rana clamata) which stick their eggs to grass. Points
about such lakes, especially where there are shrubs and willows, are the
favorite haunts of the bullfrog {Rana catesbeiana Shaw) (Fig. 117).

b) Spring-fed marsh sub-formations (Figs. 120-22) (Stations 10, 51). —
These are very similar to the marshes which adjoin bodies of water,

172

WET GROUND COMMUNITIES

but the water of such marshes, however, gets very warm in summer,
while the spring-fed marsh water is usually cool. It is the subaquatic
stratum which differs most.

One of our best examples of spring-fed marsh is at Cary, 111. (Fig.
1 20). This contains watercress, which is usually associated with springs.
The most characteristic animals are the flatworms or planarians. Pla-
nariadorotoccphala (Fig. 121) is common on the under sides of leaves, etc.;

Spring Marsh and Inhabitants
Fig. 1 20. — A spring marsh at Cary, 111.

Fig. 121. — Planaria dorotocephala; i\ times natural size (original).
Fig. 122. — The brook amphipod {Gammarus fasciatus); twice natural size.

if one puts a piece of meat into the water it will be covered with worms
within a short time. The worms follow the diffusing meat juices, often
passing through the direct sunlight, which they usually avoid. When"
they reach the piece of meat they crawl to the under side.

Associated with this planarian is Dendrocoelum (144), a, larger, light-
colored species, which does not come to the meat but is found with the
former, under boards, chips, leaves of plants, etc. The brook amphipod
{Gammarus fasciatus) (Fig. 122) occurs here also. The animals of the

TEMPORARY POND COMMUNITIES 173

vegetation above the water including the birds are about the same as
in the preceding sub-formations.

Permanent and temporary swamps are covered with trees. The
most important permanent swamps are the tamarack swamps. The
aquatic phase of these will be discussed in connection with the tamarack
swamp itself (p. 193). Temporary swamps will be discussed under the
head of temporary forest ponds.

2. TEMPORARY POND OR TEMPORARY SWAMP AND MARSH
FORMATIONS

The situations known as temporary ponds, temporary marshes or
swamps, or summer dry ponds, are common about Chicago and usually
contain water in early spring, drying before the first of June. At some
points at the south end of Lake Michigan much sand has been removed
for commercial purposes and frequently the workmen remove it to points
below the ground-water level of the spring months and accordingly make
temporary ponds which have pure white sand bottoms. A few of these
have been studied, one when it was one year old, another when about
twelve years old. These were compared with ponds of the horizontal
series which are much older.

a) Bare-bottom association. — Twelve-months-old pond association
(Station 40; Table XXXVII): In April, 1910, we found this full of
filamentous algae, and containing rotifers, copepods, and ostracods, the
eggs of all of which will probably withstand drying and may have
blown into the pond during the preceding dry seasons. There was a
single full-grown snail (Physa gyrina), a small individual (probably
Physa heterostropha), and a small long snail, Lymnaea (probably exigua).
These snails may have been carried into the pond, from other ponds a
few rods away, on the feet of turtles or frogs.

Twelve-year-old pond association (Station^; Table XXXVII) : As
such a pond as we have just described grows older, the algae continue
and the reed {J uncus balticus) comes in, together with some sedgelike
plants. In such ponds the number of species is usually greater than
at an earlier period.

In addition to the species found in the twelve-months pond, we
obtained water-beetles, which are, however, not particularly signifi-
cant because they may occur in rain pools. Cladocera, the flat snails
(Planorbis sp.), and the nymphs of damsel-flies and dragon-flies are
also found. The difference between this pond and the preceding one
is not great. Indeed, it is only when the bottom of the pond becomes

174 WET GROUND COMMUNITIES

covered with sedges that we find marked differences in the ponds of
different ages.

b) Vegetation choked temporary pond association (Stations 41, 42, 43;
Table XXXVII). — Sedges soon take possession of the bottom of such a
pond as we have been discussing. Just how long a time is required is not
known, though the pond which we are about to discuss is probably
several hundred years old. Here we find nearly all the groups men-
tioned as occurring in the younger ponds, but also certain ecological
types which are characteristic of sedge-bottomed ponds. Most notable
is the small green, flat, cigar-shaped worm {Vortex viridis) which usually
occurs in numbers, and a small brown species of Mesostoma similar
in form but brown in color. With them are often small larvae of
dytiscid beetles (species unknown), caddis-worms (Phryganeidae) with
cases made from pieces of grass (their relation to those in permanent
ponds is not known), and the snail (Lymnaea modicella).

As such a pond grows older the sedge becomes thicker and other
plants make their appearance. What is known as low prairie develops.
At such a stage the small ponds like those we have been describing
usually become partially filled and so never contain the best development
of the older temporary pond community. We accordingly turn to the
later history of the ponds discussed in the preceding chapters, which
represent the best development of the temporary pond communities.

In a forest climate when ponds are filled and drained they are
occupied by forest. In the steppe climate they are occupied by steppe
or prairie. In the forest border area, where our studies have been
carried on, some ponds when filled are occupied by prairies, others by
forest. Dr. Cowles is of the opinion that ponds with gently sloping
sides and bottoms become covered with prairie, while those with steep
slopes become covered with forest (Fig. 123).

As ponds, such as we have discussed in the preceding chapter,
become ecologically old, they dry in dry seasons. They usually become
occupied by cattails, equisetum, or other grasslike plants. The red-
winged blackbird (Fig. 124) occasionally nests in them. At such a
stage the isopods (Asellus communis and Mancasellus danielsi), amphi-
pods (Eucrangonyx) (Fig. 113), and snails (Lymnaea reflexa) (Fig. 125;
compare with Fig. 104, p. 149). are common. The fringe-legged mosquito
(145) and the common marsh mosquito (Fig. 126) breed in such situations
while the crayfishes and various of the old-pond species continue.

When such a stage is reached, it is only a step to the typical tempo-
rary pond. If the ground- water level is lowered, as is the case in many

TEMPORARY POND COMMUNITIES

175

Semi-temporary Pond or Marsh and Inhabitants

Fig. 123. — General view of Pond 93, which is occupied by Sagittaria and grass-
like plants.

Fig. 124. — Side view of a red-winged blackbird's nest. Photo by T. C. Stephens.

Fig. 124a. — The same from above.

Fig. 125. — A temporary pond form of the snail (Lymnaea reJIexa): natural size.

176

WET GROUND COMMUNITIES

of the ponds south of Lake Michigan, such ponds usually become grassy
in the middle and often typical temporary prairie ponds. Here we find
the green flatworm (Vortex), vernal planarians (Planaria velata), great

y*

Fig. 126. — The common marsh mosquito {Anopheles pnnctipennis Say); much
enlarged (from Williston after Smith). The details are such as to enable one to
recognize this species of mosquito: (1) adult female; (2) her palpus; (3) her genitalia;
(4) part of a wing- vein showing scales; (5) anterior, and (6) middle claws of the male.

numbers of Entomostraca, belonging to all orders. Of the last there are
many very large cladocerans, the copepods (146) (Cyclops viridis
americanus) (Fig. 127), the red copepod (Diaptomus stagnalis) (Fig. 128),

TEMPORARY POND COMMUNITIES

177

the ostracod (Cyprois marglnata X147) (Fig. 129), and the fairy shrimp
(Eubranchipus) (148) (Fig. 130), all of which are characteristic of tempo-
rary ponds. Red mites (Fig. 131) are also common (149).

Professor Child (unpublished) has noted that the distribution each
spring of Eubranchipus and of other temporary pond species is modified

Temporary Grassy Pond Animals

Fig. 127. — A temporary pond copepod {Cyclops viridis americanus Marsh); 35
times natural size (after Herrick and Turner) .

Fig. 128. — The red copepod (Diaptomus stagnalis) from temporary pond; 12
times natural size, left antenna omitted (after Herrick and Turner).

Fig. 129 — The temporary pond ostracod {Cyprois marginata); 35 times natural
size (after Sharp).

Fig. 130. — The fairy shrimp (Eubranchipus); 3 times natural size.

Fig. 131. — The red mite (Hydrachna sp.); 10 times natural size.

by the rainfall of the preceding season. When the rainfall of the pre-
ceding season has been great, the temporary pond species are found only
in the smallest and highest (above ground-water) ponds such as would

i 7 8

WET GROUND COMMUNITIES

develop in the place of one of the small ones with sandy bottom. Follow-
ing dry seasons the temporary pond species are found in ponds which do
not usually dry in summer, but which were dry the preceding summer.
It has been shown that the eggs of Eubranchipus must be dried and

Fig. 132. — The little smoky mosquito (Aedes fitsca O.S.); much enlarged (from
Williston after Smith): (1) adult female; (2) her palpus; (3) palpus of the male;
(4) anterior; (5) middle, and (6) posterior claws of the male.

frozen before they will hatch. The relation of their distribution, follow-
ing the seasons of different rainfall, suggests that some definite degree
of drying must be attained to insure hatching as well as that the eggs
are probably blown about by wind. One autumn, about 1900, there was

TEMPORARY POND COMMUNITIES 179

early freezing and cold weather followed by warm weather of a very
springlike character in December. Professor Child observed that the
Eubranchipus hatched during this period of warm weather. Cold weather
came on soon after and most of those that had hatched died before
reaching sexual maturity, and for several years after the species was
very scarce in the vicinity of Chicago. Eubranchipus is found only in
grassy ponds, possibly because the forested ponds do not dry sufficiently
in summer. We have found it on one occasion in woods, but this was

34

I

33 : 135

The Bare Sand Water Margin and Inhabitants

Fig. 133.— Margin of Lake Michigan at Buffington.

Fig. 134. — The beach tiger-beetle (Cicindela hirticollis); i| times natural size.

Fig. 135.— The beach ground beetle (Bembidium cannula) ; i\ times natural size.

in flood-plain pools following an early spring flood and might have been
due to the washing-in of eggs or young.

c) Forest temporary pond sub-formation (association) (Station 50;
Table XXXVII).— These are characterized by the absence of both
Diaptomus and Eubranchipus. The Entomostraca are chiefly ostracods,
such as Cyprois marginata, which occurs in grassy ponds. Vortex, mos-
quito larvae, the little bivalve (Musculium), small earthworms (Lum-
briculus), and the larvae of a beetle (Dascyllidae) are also very common.

i8o

WET GROUND COMMUNITIES

The amphipods and sowbugs of the earlier stages are still present. This
is the breeding-place of such mosquitoes as the little smoky mosquito
(Aedes fuscus) (Fig. 132, p. 178) (145, 99c).

3. COMMUNITIES OF MARGINS OF BODIES OF WATER

There is always a narrow area along the margins of bodies of water
which is difficult to classify as water or as land. The association of
this area is the one with which we now have to deal.

Along the margins of young ponds and lakes is an area which is
characterized by being made up of wet sand or mud which is sub-
merged at high water and moist at
other times.

a) A ssociation of the terrigenous mar-
gins of large lakes (Fig. 133) (Stations
57, 58; Table XXXVIII).— Here we
find the springtails the simplest in-
sects, the shore bugs (150), Saldidae,
especially Salda humilis Say, a large
number of tiger-beetles (151) (Cicin-
dela hirticollis) (Fig. 134) (C cupras-
cens), together with numerous small
flies.

The ground beetle (Bembidium
cannula) (Fig. 135) and numerous
scavengers are common because the
beach is often strewn with dead ani-
mals which have floated ashore. The
relations of the drift to other com-
munities will be discussed in the
chapter on dry forests. The spotted
sandpiper feeds here, and with the piping plover often breeds not far
from the water's edge. Under conditions of rapid recession of the lake
such a margin is separated from the wave-action. It is then rapidly
transformed into the next association.

b) Association of the terrigenous margins of ponds and small lakes
(Stations 30, 40; Table XXXIX). — This association differs from that of
the large lake in that the scavengers are absent and the animals much
less active, not moving about so rapidly. Here we find springtails,
Saldidae of another species, and the toadbug (Gelastocoris oculatus) (150)
(Fig. 136), which is colored like the ground and is found hopping about

Fig. 136. — The bare pond and river-
margin toadbug {Gelastocoris oculatus) ;
greatly enlarged (after Lugger).

WATER MARGIN COMMUNITIES 181

close to the water. The tiger-beetle of the Lake Michigan shore is dis-
placed by that of another (Cicindela repanda) which is less active. With
these is the hooded grouse locust (Paratettix cucullatus) (Fig. 137) (40,
p. 419). The small semiaquatic snail (Lymnaea modicella) is frequently
present in numbers.

The nests of the spotted sandpiper (108, 141) and the yellowlegs are
found here, and the birds no doubt feed upon the invertebrates present
on the margins of the ponds and of the shallow water.

c) Association of sedge margins of ponds and small lakes (Stations
32-34; Tables XL, XLI). — As time goes on, the sandy margin is
captured by sedges which are scattered at first, so that the animals just
discussed continue for a time among them (Figs. 138, 139). Finally,
however, the ground becomes sodded over
with sedges and a low prairie animal commu-
nity comes in, and the bare ground animals
disappear. In the case of ponds which are
to develop into forest this stage is found
only along the young ones. The sedges are
soon displaced by shrubs and the sedge
communities give way to shrub.

d) Associations of shrub margins of ponds
and small lakes (Fig. 140) (Stations 34, 37,
44; Tables XLI, XLII).— Mr. Allee has
verified my observations to the effect that . Fl ^ ^--Hooded grouse

. locust {Paratettix cucullatus)

the aquatic part of this formation is almost ( a f ter Lugger).

entirely barren; however, in summer we get

the short-winged and armed grouse locust (Tettigidea armata Morse,

and parvipennis Harr.) (40) and the slimy salamander (Plethodon

glutinosus) (152) (Fig. 141). Of the birds associated with the water

we have here the wood-duck and the green heron.

4. MARGINS OF RIVERS

(Station 29)
Here the sandy margin is similar to that of the ponds and lake.
Along the Fox River we find the mole cricket (40) which burrows into
the sand. Mud margins are rather barren except for occasional beetles.
The margins of rivers which are grassy or marshy are like those of ponds
and lakes. The margins of the Calumet and lower Deep rivers are
covered with marsh plants and saturated with water in spring. They
are the nesting-places of the long-billed marsh wren (Figs. 142, 143) and
many other marsh birds (108, 153).

182

WET GROUND COMMUNITIES

139

Fig. 138. — Prairie-like stage of a pond margin.
Habitat of Cicindela tranquebarica in the pine
zone of the ridges at the south end of Lake
Michigan. The dark portion in the foreground
is the shadow of a tree. At the left is the
cattail zone of the depression; between a and
b, the sedge zone; between b and c the zone of
high-depression plants. The white blossoms
here are those of Parnassia caroliniana; their
distribution, September, 1906, corresponds ap-
proximately to the distribution of the larvae of
C. tranquebarica, which arose from eggs laid in
May and June, 1905. The portion to the right
and above c represents the higher portion of the
ridge and the habitat of C. scutellaris. Reprinted
from the Journal of Morphology.

Fig. 139. — The upper part of the burrow of
C. tranquebarica, pupal cell shown by dotted
line; \ natural size. Reprinted from the Journal
of Morphology.

WATER MARGIN COMMUNITIES
III. General Discussion

183

The areas which we have been discussing in this chapter are the
tension lines between the land and the water. It is in such areas that
ecologists have learned most about succession and about the tendencies

Fig. 140. — Pond 95, showing the death of the pond by the growth of buttonbush.
Fig. 141. — The shiny salamander (Plethodon glutinosus); about twice natural
size (after Fowler).

and processes in animal formations and associations. In this chapter
we first considered the marshes which border the lakes and ponds about
Chicago. Dr. Cowles and others have pointed out that lakes and ponds
are filled by organic debris and that bulrushes invade from the shore and
" capture" the ponds and lakes. As the bulrushes and other plants

184

WET GROUND COMMUNITIES

invade, the girdle of marsh which is the nesting site of the birds men-
tioned moves farther and farther toward the center of the pond or lake,
the former positions being occupied by shrubs, such as buttonbush or
willow, or in some cases by prairie. Such a situation is in unstable
equilibrium.

Turning to the margins of ponds, lakes, and rivers, we note that
at the beginning we often have the bare sand. This is first occupied

Fig. 142. — The long-billed marsh wren's nest. The nest unopened.
Fig. 143. — The nest torn open showing the eggs.

by reeds and sedges, and finally by shrubs. It is this reed and sedge
group, or the buttonbush, that invades the swamp as it fills with bul-
rushes and cattails. We note accordingly that the vegetation which
appears on the shore invades the pond as it fills. The last stage of
a pond is either a buttonbush swamp or a low prairie which we shall
discuss in later chapters.

WET GROUND ANIMALS

185

TABLE XXXVII
Temporary Ponds of Different Ages
The numbers standing at the heads of the columns where months or years are
not indicated refer to the number of the pond in question when counted from the lake.
J.P. is a pond south of Jackson Park.

Common Name

Scientific Name

Undifferen-
tiated

Prairie

For-
est

12 Mo.

12 Yr.

4

55

JP.

94

Rotifer

*
*

*
*

*

*

*

*
*
*

*

*
*
*
*
*
*

*

*
*

*

*

*
*
*
*
*
*

*
*
*
*
*
*

*

*
*

*
*
*

*

*

*

*
*
*
*

*

*

*
*

*
*
*

*
*

*

Copepod

Cladoceran

Ostracod

Snail

Physa gyrina Say

Lymnaea obrussa exigua
Lea

Snail

Ground beetle

Scavenger beetle

Bembidium sp

Aphodius fimetarius
Linn

Small water-bug

Scavenger beetle

Zaitha fluminea Say. . .

Hydrophilidae

Gerridae

Water-mite

Flat snail

Hydrachna sp

Planorbis

Dragon-fly nymph ....
Toad-shaped bug

Enallagma,

Gelastocoris oculatus
Fabr

Green flatworm

Brown flatworm

Vortex viridis M. Sch .
Mesostoma sp

*

Springtail

Caddis-worm

Pond snail

Collembola

Lymnaea reflexa Say. .
For

Red copepod

Fairy shrimp

Forbes

Amphipod

Planaria velata Str. . . .
Eucrangonyx gracilis
Sm

*

Isopod

Asellus communis Say.
Culicidae

*

Mosquito larva

Bivalve

*

Musculium secure
Prime

*

Ostracod. . .

Cypris fuscata Jurine. .
Cyprois marginata

Ostracod

*

Beetle larva

Dascyllidae

Lumbricidus

inconstans Smith

*

Annelid worm

*

i86

WET GROUND COMMUNITIES

TABLE XXXVIII

Animals Frequenting the Moist Margin of Lake Michigan

(Stations 57, 58)

Common Name

Scientific Name

Month

Flesh-fly

Sarcophaga sp

Chrysomyia macellaria Fab

4-9
4-9

4-9
4-9
4-9

6-8

Flesh-fly

Flesh-fly

Cynomyia cadaverina Des

Hister beetle

Saprinus patruelis Lee

Bembidium carinula Chd

Ground beetle

Tiger-beetle

Tiger-beetle

Cicindela hirticollis Say

Cicindela cuprascens Lee

7-8

TABLE XXXIX

Animals Resident on the Margin of a Twelve-Year-Old Artificial Pond and

of Wolf Lake (Sandy)

(Stations 30, 40)

Common Name

Scientific Name

Month

Ground beetle

Bembidium variegatum Say

Snail

Lymnaea humilis modicella Say

Gelastocoris oculatus Fabr

4-9
4-9

4-9
4-9

Toad-shaped bug

Tiger-beetle

Cicindela re panda Dej

Hooded grouse locust

Paratcttix cucullatus Burm

WET GROUND ANIMALS

187

TABLE XL

Animals Recorded from Sedge-covered Pond Margins

(Stations 32, 33)

Common Name

Scientific Name

Month

Snail

Lymnaea humilis modicella Say

Succinea retusa Lea

Snail

4 9

Snail

Succinea avara Say

4 9

May-fly

4 9

Toad

4 9

Diving spider

Dolomedes sexpunctatus Htz

4 9

Spider

Pirata insularis Em

4 9

Walking-stick

Diapheromera femorata Say

£ n

Grasshopper nymph

A crididae

e g

Damsel-bug

Reduviolus ferns Linn

8 n

Centipede

Lithobius sp .

9

Spider

4 9
8-9
8 n

Long-bodied spider

Tetragnatha laboriosa Htz

Spider

Tibellus duttoni Htz

9
8 n

Eucta candata Em

9

Orb-weaving spider

Epeira foliata Koch

5
5-9

7-8

9
g

Augochlora confusa Rob

Ant

P oner a coarctata La" r

Diabrotica 12-punctata Oliv

Root beetle

Diabrotica vittata Fab

8

Spider

8

Ambush-bug

Phymata fasciata Gray

8

Thyreocoris unicolor P B

8

Bug

Philaronia bilineata Say

9
8-9

Red-legged grasshopper

Stinkbug

Melanoplus femur-rubrum DeG

Cosmopepla camifex Fab

Ant

Midge

Formica fusca var. subsericea Say

Chironomidae

1

188 WET GROUND COMMUNITIES

TABLE XLI

Animals Recorded from the Margin of Pond 8 (Mixed Sedges and Shrubs)

by Mr. B. F. Isely
(Station 34)

Common Name

Scientific Name

Month

Lygaeid. .

Cytntis angustatus Stal

7-8

Apple-leaf hopper

Lacebug

Empoasca mali LeB

Physatochila plexa Say

7-8

Jassid

Draecidacephala mollipes Say

7-8

Dusky plant-bug

Cranberry lygaeid

Adelphocoris rapidus Say

Ischnodemus f aliens Say

7-8
7-8

Beetle. .

Nodonota tristis Oliv

7-8

Ground beetle

Anomoglossus pusillus Say

7-8

Ant-like flower-beetle

Stereopalpus tnellyi Laf

7-8

Leaf-beetle

Chalepns hornii Sm

7-8

Mordellid

Mordellistena aspersa Mel

7-8

Pachybrachys abdotninalis Say

7-8

Strawberry beetle

Typophorus Gemellus sellatus Horn

Lucidota punctata Lee

6-9

Lampyrid

7

Lampyrid

Lampyrid

Pyractomena borealis Rand

7

Lucidota atra Fab

7

Metallic wood-borer

Pachyscelus laevigatus Say

7

Dascyllid

Ptilodactyla serricollis Say

7

Hemileuca rnaia Dru

7

Short-winged brown grass-
hopper

Slender meadow grasshopper .
Short- winged meadow gr'hop.
Fly

Stenobothrus curtipennis Harr

7-8

Xiphidium fasciatum DeG

7-8

7-8

Tetanocera umbrarum Lin

7-8

Fly

Fly

Fly

7-8

7-8

Tetanocera saratogensis Fitch

7-8

Horsefly .

Chrysops aestuans V.W

7-8

Horsefly

Chrysops callidus O.S

7-8

Syrphus fly

Mesogramma marginata Say

7-8

TABLE XLII

Animals Recorded from the Willow and Buttonbush. Margins of Ponds

52 and 93. Records by Allee are Indicated

(Stations 37, 44)

Common Name

Scientific Name

Month

Plant-bug

Adelphocoris rapidus Say (young)

Cosmopepla carnifex Fabr

7-8

Stinkbug . .

7-8

Fulgorid

Amphiscepa bivittata Say

7-8

Jassid. .

Parabolocratus viridis Uhler

8

Smeared dagger-moth

Ant

Acronycta oblinita S and A (Allee).. . .

Aphaenogaster treatae Forel (Allee)

Tetanocera sp. (Allee)

8
8

Flv

8

Epeira trlvittata Key. (Allee)

8

Leaf -beetle . .

Calligrapha midtipunctata var. bigsby-

Leaf-beetle

Typophorus canellus aterrimus Oliv ....

CHAPTER XI

ANIMAL COMMUNITIES OF SWAMP AND FLOOD-PLAIN FORESTS

I. Introduction

Swamp forests are those which arise in the areas formerly occupied
by ponds and lakes and which grow in water or very wet soil. About
Chicago the many coastal and morainic lakes of earlier periods have been
filled by organic detritus and more or less completely occupied by trees.
Often the trees have grown upon floating bogs such as sometimes occur
about lakes, though sometimes they have sprung up on solid ground and
compact organic detritus.

II. Swamp Forest Formations and Associations

We shall consider these forests genetically: the marsh which often
appears first, the shrub stage which follows, and finally the forest.

I. THE ELM-ASH SWAMP FOREST COMMUNITIES

a) The marsh association (Station 52; Table XLI). — One of the best
examples of this community is at the north end of Wolf Lake, Ind. The
youngest part is occupied by bulrushes and Hibiscus, and covered in the
spring by about a foot of water which teems with small crustaceans,
mosquito larvae, and red water-mites. Lymnaea reflex, usually about
half the size of the specimens (100) of permanent ponds, and the small
bivalve (Musculium) are present. As the season advances the water
dries up and the eggs of the crustaceans and adult mollusks live through
the dry season on the bottom of the pool. Above the water on the
Hibiscus are the small Succinea retusa (91, 100), which belong to the
forest edge and low prairie.

b) Shrub association (forest edge sub-formation) (Station 52; Table
LXIII). — Surrounding the central pool which we have described is
usually a girdle of buttonbush. Here we recognize several strata. The
subterranean stratum has few inhabitants. We have recorded none.

The ground stratum is not inhabited by many animals. The wood-
cock and the northern yellowthroat (108, 153) probably occasionally
nest here on the ground, possibly also the common shrew (Sorex
personatus St. Hil.) (142). There is no distinct field stratum, as the

189

190 WET FOREST COMMUNITIES

thickness of the shrubs prevents the growth of herbaceous vegetation.
The shrub stratum is the chief habitat.

The buttonbush is remarkably free from plant-feeding animals.
Occasionally some of the willow-eaters, such as the larva of the smeared
dagger-moth, are found on it, but never in any numbers. This stratum
is the resting-place of many of the insects whose early stages inhabit
water. When the plants are in blossom, it is visited by many flower-
frequenting insects, such as the bumblebee (40).

Mr. Visher has recorded a number of nesting birds in this girdle.
The wood-duck usually makes its nest here in some hollow tree and lines
it with feathers; where stumps or rotten trunks are found the prothono-
tary warbler sometimes nests; Traill's flycatcher (Empidonax trailli
Aud.) places its nest well up in the branches and leaves of the bushes.

c) Forest formation (Stations 52 and 53; Table L). — As time goes
on and the marsh fills with organic detritus, the buttonbush which is
continually encroaching upon it comes to occupy a position farther in,
while its former location is taken by the ash, which is the next girdle
outside.

The ash is succeeded by the American elm and the basswood. These
are frequently considerably mixed with the ash, but the two girdles can
be distinguished in the Wolf Lake Forest. For convenience we shall
treat these two girdles (associations) together under the head of the wet
forest formation.

The subaqueous and subterranean-ground strata: The subterranean
portion is inhabited by earthworms. On the higher parts there are
doubtless other subterranean forms. Where the roots of the grapevine
are in the drier soil, the vines are infested with the aphid (Phylloxera)
which makes galls on both roots and leaves. The depressions of these
forests are filled with water in spring and support temporary pond ani-
mals such as we have discussed on p. 179.

In the Wolf Lake woods we noted in the spring of 19 10 that the small
red spiders (Trombidium sp.) were numerous. Centipedes, crane-fly
larvae, and ground beetles occur under the leaves. Hancock (40, p. 419)
states that the obscure and Indiana grouse locusts [Tettix obscura Han.
and Neotettix hancocki Bl.) are found in such forests. Under pieces of
rotten wood are sometimes found specimens of the small snail (Zonitoides
arbor eus), which is first to appear in forests developing from the button-
bush swamp stages. On highest ground we get two other snails (Poly-
gyra monodon and Pyramidula striatella Ant.) (91, 100). In the fallen
logs we find a considerable number of borers (Parandra brunnea Fabr.

SWAMP FOREST COMMUNITIES 191

and others) and under the loosened bark are centipedes (Lithobius), milli-
pedes (Polydesmus), and beetle larvae (Pyrochroidae) which are flattened.

While we have no actual records of mammals in such situations,
doubtless the varying hare (Lepus americanus Erx.) which frequents
marshy woods with thickets such as the buttonbush, the common shrew,
which nests under logs, and the mink (Mustela vison lutreocephala Harlan),
all have been visitors if not residents in such situations in the past. The
wood-duck, the woodcock, and prothonotary warbler often nest in such
woods.

Field stratum: The field stratum is inhabited by small flies, such
as crane-flies, midges, and mosquitoes (Chironomidae and Culicidae),
occasional spiders, such as Theridium frondeum, parasitic hymenoptera
(Pimpla inquisitor Say, Ichneumon mendax Cress.) and the scorpion-fly
(Panorpa), which breeds in the ground.

Shrub stratum : The shrubs consist chiefly of buttonbushes and low-
hanging grapevines. The vines frequently have conspicuous insect
galls. One called the grapevine apple gall, because of its shape, is due
to the larva of a small fly (Cecidomyia vitis-pomum W and R) (137);
another which is a pointed tube on the leaf is due to Cecidomyia viticola.
Wartlike galls on the under side of the leaves are due to Phylloxera
vastratrix PL (Fig. 277, p. 273) (150), an aphid which, when introduced
into France, threatened to destroy the vine industry. These occur only
on the vines on high ground where the roots, upon which a part of the
life of the aphids is spent, are out of water. Several grape insects, includ-
ing the fulgorid bug (Ormenis pruinosa Say), have been taken.

Tree stratum: The tree stratum of this girdle has not been studied,
because the study of the tree stratum in general is difficult. The white
ash is, however, attacked by many insects. Felt (137) and Packard (154)
record a number. One of the most difficult groups to secure is the
" borers" of the solid wood or sapwood of trunk and twigs. These are
chiefly beetle larvae, especially the Cerambycidae (155), or long-hprned
beetles. The larvae of these are legless and only slightly larger at the
anterior end. Another prominent family is the metallic wood-borers or
Buprestidae (155). The larvae of these are also legless and may be dis-
tinguished from the preceding by a broad, flattened enlargement just
behind the head. The ecology of these two families alone is a subject
for a work the size of this volume (see 137 and 154). The four-marked
borer (Eburia quadrigeminata Say) is said to occur on the ash through-
out Indiana (156). The elm and basswood likewise have many borers,
some in common with the ash.

192 WET FOREST COMMUNITIES

The insects feeding on the leaves are numerous on all the trees. The
following are common to the three trees mentioned (137): the cater-
pillars of the hickory tussock-moth, the American dagger-moth, the forest
tent caterpillar, the white-marked tussock-moth; each has a preference
for one of the trees. The larvae of several other common moths occur
on two of the trees, a few are confined to one. Beetle and sawfly larvae
also attack the leaves. Each tree has its characteristic gall insects and
galls; for example, on the elm, the coxcomb gall (Colopha ulmicola Fitch),
on the ash, the midrib gall (Cecidomyia verrucicola O.S.). These are
believed to be confined to particular tree species.

According to Wood (21) such forests are the chief haunts of the gray
squirrel. The green heron is especially likely to nest on the low trees
of such a forest if they are near water.

2. OTHER TYPES OF SWAMP FOREST COMMUNITIES

The swamp forest formation is well developed in the Skokie marsh
area. We have visited these woods at a point west of Dempster Street,
Evanston. This was originally characterized by trees very much larger
than those at Wolf Lake. The soil at Wolf Lake is sand, while that at
Evanston is clay, which is probably more favorable for trees. However,
the most important cause of the greater luxuriance is greater age.
The subterranean stratum has not been studied.

The ground stratum: Here we find, in addition to those species
of the temporary ponds at Wolf Lake, a snail (Aplexa hypnorum Linn.)
which is characteristic of very transient ponds (100).

On November 27, 1903, the condition of the animals of this stratum
was noteworthy. In the lower moister parts of the wood we found the
mollusks, especially Pyramidula alternata, in groups under logs. One of
these groups contained 1 2 individuals. Under another log was a group
of about 50 ground beetles (Platynus sp.). Under one small piece of
bark were found three ground beetles, three rove-beetles, one slug, and
two snails. Under another, one tetrigid or grouse locust, several ground
beetles, and a rove-beetle. Under the bark of a log on the above date
we found the hibernating parasitic hymenoptera (Ichneumon extrematatus
Cress., galenus Cress, and mendax), also a queen white-faced hornet
(Vespa maculata), which with its colony builds a large spherical nest
in a tree in summer.

Most noticeable of all was a group of several hundred small blue
chrysomelid beetles (Haltica ignita Illig.). They were under the leaves
at the base of a tree down the sides of which individuals of the same

TAMARACK FOREST COMMUNITIES 193

species were moving. Such groupings are common among hibernating
insects and are believed to keep the temperature a little higher. Baker
(100) has studied the wet forest near Shermerville, 111. In his Stations
7-1 7 the forests are ecologically older. (For birds and mollusks present,
see 100, p. 468.)

3. THE TAMARACK SWAMP COMMUNITIES

(Stations 54, 54a; Tables XLIII-XLV)
Tamarack swamps develop about deep lakes. Floating plant debris
supports first water-lilies and later bulrushes and cattails. Upon these
grow shrubs, such as the leather-leaf and the willows; these make condi-
tions suitable for the poison sumac and young tamaracks. The semi-
aquatic plants are thus succeeded by the shrubs and finally by the
tamarack.

The aquatic communities have not been studied in a typical tamarack
lake, but there is no reason to suppose that they differ in any important
way from the aquatic communities of other old bodies of water.

a) Floating bog and forest edge association (Tables XLIII, XLIV). —
The floating bog of cattails and bulrushes is usually full of low places in
which water is present the year round. Here we find the typical
animals of semi-temporary ponds, as described on p. 150. The various
frogs of the marsh probably breed here. Another aquatic habitat of
some interest is the water-holding leaves of the pitcher-plant (158).
The pitcher-plant mosquito (Wyeomyia smithii) is known to breed in the
leaves of pitcher-plants only. These are accompanied by the larvae of
midges and large numbers of dead insects which crawl into the pitchers
and cannot get out on account of the presence of many hairs which pro-
ject inward along the wall of the entrance.

The surface of the bog is frequented by marsh spiders, insects, and
frogs, only a few of which belong especially to pre-tamarack bogs. The
inhabitants of the vegetation (field stratum) are like those on the vege-
tation over other marshes, belonging chiefly to low prairies. The edge
of the tamarack woods (Fig. 144) is a characteristic forest margin.
Except for the presence of some of the tamarack leaf-feeders, such as
the larch sawfly larva and measuring-worm, it possesses few species
different from the margins of other marshes (Fig. 145).

b) Tamarack forest formation (Table XLV). — Pools: The pools
within the forest proper contain old-pond animals together with some
mosquito larvae (such as those of Culex canadensis) which are char-
acteristic of pools in all moist and mesophytic forests (see 99c).

194

WET FOREST COMMUNITIES

Representatives of the Tamarack Swamp Community

Fig. 144. — View in the dense vegetation of the tamarack swamp.

Fig. 145. — Female orb-weaver (Epeira gigas) ; about natural size.

Fig. 146. — The brindled locust (Melanoplns punctulatiis) ; natural size.

Fig. 147. — An earwig (A pterygida aculeata); natural size.

Fig. 148. — An engraver beetle destroyer (Cleridae, Thanasimus dubius) ; 3 times
natural size (from Blatchley after Wolcott).

Fig. 149. — The bark of the tamarack, showing the work of the engraver beetle
(Polygraphias rnfipennis) .

Figs. 150, 150a. — Pickering's tree-frog (Hyla pickeringii); about two-thirds
natural size (after Fowler).

TAMARACK FOREST COMMUNITIES 195

Ground stratum: On the sphagnum, which sometimes occurs in the
pools, various insects and spiders occur, including, according to Hancock
(40), two species of sphagnum crickets. On the higher ground numbers
of typical moist forest animals occur sparingly. Frogs are often numer-
ous. The common frogs (Rana pipiens and clamata) and the marsh
tree-frog (Chorophilus nigritus) occur in summer. The wood-frog and
Pickering's tree-frog {Rana sylvatica and Hyla pickeringii, Fig. 150) are
regular residents; probably both breed in the pools (139) between the
hummocks. Farther north the hermit thrush nests on the hummocks
amid the dense undergrowth. This is also the typical haunt of the
varying hare (Lepus americanus Erx.) (83, 142, 143), which is white in
winter and brown in summer; it is common in tamarack swamps farther
north. The lynx (p. 15) was probably once common near Chicago and
is most likely to have frequented these swamps. Adams (83, 42) records
its tracks on the hummocks of the tamarack swamps on Isle Royale in
Lake Superior. Judged by its tracks it wanders far. It feeds largely
on hares, the numbers of which fluctuate (inversely) with the numbers of
lynx. The otter (Lutra canadensis Schr.) and Cooper's lemming mouse
might be added as probable former residents (143, 21).

Field stratum : This is confined to hummocks supporting herbaceous
plants. Insects, spiders (159), etc., are common; some characteristic
species occur.

Tree stratum: The brindled grasshopper (Melanoplus pundulatus)
(Fig. 146) has been found on the low branches of the tamarack and
deposits its eggs on the bark of the trunk or on stumps. Several other
insects have been recorded as common on the tamarack, among which
are a sawfly, an earwig (Fig. 147), a lappet moth, and a woolly aphid,
but we have not taken all of them. (See 137, II, 838, and I, Plate 18.)
The tamarack is infested by bark beetles. In the swamp at Mineral
Springs, Ind., we found one (Polygraphus rufipennis) (137), sometimes
also Dendroctonus simplex Lee, common under the bark of partially dead
trees (Fig. 149). The larvae of the clerid beetle {Thanasimus dubius)
(Fig. 148) (137) occur with the bark beetles and feed upon them.
The adult of the clerid (137) appears in spring, having wintered over
as adult or in the late larval or pupal stage. It goes about on the
bark of trees, seizing the bark beetles and later laying eggs at the
openings of their galleries. The larvae invade the galleries and feed
upon the eggs and larvae of the bark beetles. Felt states that two
other bark beetles attack the tamarack (160). In this marsh the bark
beetles have killed a number of trees. In summer the area of dead ones
may be seen a mile away.

i 9 6 WET FOREST COMMUNITIES

Farther north the blackburnian warbler nests here. The tree stratum
of primeval conditions usually included the pine marten {Maries
americana Tur.). It lives in trees in dark coniferous forests. Merriam
(142) says that it nests in a hollow tree or log, rarely on the ground.
It preys upon partridges, rabbits, squirrels, chipmunks, mice, shrews,
birds' eggs, young birds, and frogs and toads. It disappears when
civilized man settles the country. The marten's close relative, the fisher
(Marks pennanti Erx.), is said to be the wildest of all wild animals. It
is somewhat similar (21, 22, 162) to the marten in habits.

c) The pine-birch transition girdle (Station 54; Table XL VI). — This
succeeds the tamaracks and contains a few old trees of this species. The
pools are all dry in summer, though they may contain water in spring.
The subterranean stratum has not been investigated.

The ground stratum includes the frogs of the tamarack formation
(Hyla pickeringii) . Insects, spiders, centipedes, and snails, which belong
chiefly to mesophytic forest, are more numerous than in the tamarack
stage. Nesting of the ruffed grouse likewise indicates that the swamp
stage is past. The field and shrub strata likewise include more of the
mesophytic forest animals than the true tamarack stage.

The tree stratum has not been studied. The trees are white pine,
yellow birch, and an occasional maple. Felt (137) records no insect
common to these two trees. There are several common to the white
pine and tamarack (larch lappet, engraver beetle, etc.). Pines have
many borers and few leaf-feeders. Each borer usually prefers a certain
part, as the trunk, limbs, or growing shoots; some, as the white-pine
weevil (Piss odes strobi Peck) (161), attack young pines. Felt records
about 25 injurious insects common to birches and maples in general
and one or two which occur only on yellow birch. The great crested
flycatcher nests in holes in dead limbs; the wood pewee nests on
horizontal limbs, and the red-eyed vireo builds a nest in trees from
5 to 40 ft. from the ground. Dead birches form suitable nesting-
places for woodpeckers. The Canada porcupine (142) which we have
noted in the ground stratum is a good climber and feeds largely in
the trees, which it often girdles.

d) The geographic relations of the animals. — Most of the non-aquatic
animals of the swamps are commonly said to belong to species common
farther north where conifers dominate. However, our lists and the
unpublished work of Messrs. Wolcott and Gerhard do not bear out this
conclusion. Some of the species of these swamps doubtless formerly
occurred among the hemlocks of Southern Michigan.

FLOOD-PLAIN FOREST COMMUNITIES 197

e) Fate of the formation. — Most of our tamarack swamps are in the
regions which are commonly dominated principally by beech and maple.
In the higher portions of the tamarack swamps are found several species
characteristic of beech woods and other mesophytic woods. These are
the wood-frog, the large slug, the snail (Polygyra albolabris) and the
red-backed salamander (Plethodon cinereus) and the spider (Castianeira
cingulata). These indicate that beech and maple are to follow.

4. FLOOD-PLAIN AND RAVINE FOREST COMMUNITIES

As we have noted on pp. 87-93 an d 1 08-1 13, streams often develop
by head-on erosion into uplands of rock or clay.

a) Streams developing in rock. — In case the upland is of rock, the
beginning of the stream is a lower place in the slope of the rock through
which water flows when it is raining. Vegetation is usually absent. If
there are broken pieces of rock at the sides or in the course of the inter-
mittent stream, some of the forms mentioned on p. 218 may be present.
Until it becomes permanent or has cut itself a deep, straight-sided
channel, it is inhabited by the animals which inhabit the bare rock of
hills or hillsides. After the stream has cut such a channel, there are
always small piles of fine soils which support nettles and other mesophytic
plants similar to those of the old mesophytic flood-plain. Flood-plain
animals appear early in the development of the stream.

b) Streams developing in clay. — Along the north shore we have an
opportunity to study the vegetation of ravines of all ages corresponding
to the aquatic stages described on pp. 87-93. The slightly lower places on
the bluff side in which water runs only when it is raining are usually too
steep to support plants and animals as regular residents, and have the
same incidental forms as the steep bluff (p. 210). Later, when the sides
of the gully become less steep, it is similar to if not identical with the
second bluff stage (pp. 212-214); later, like the third (p. 215), and still
later, like the young forest stage. There appears to be little or no
difference between the bluff and the sides of young ravines. The outer
ends of ravines as much as a mile and a half long are usually in the shrub
stage and possess the shrub community. In favored situations the sapling
forest, apparently identical in its animal associations with that of the bluff
(p. 215), grows up. Up the stream, well back from the lake, a distance
of a fourth of a mile, conditions become very different. A very meso-
phytic forest grows up. In this we have possibly some special features
under primeval conditions, but in the ravines along the north shore
where the forest is so much disturbed, ravines do not differ particularly

198 WET FOREST COMMUNITIES

from the rest of the forest, but animals of the forest collect in the
ravines in dry seasons and apparently leave the ravines in the wet
seasons.

We have noted that the animal species living at the headwaters of a
stream may move inland as the headwaters move inland. This is true
of aquatic species. In the case before us none of the species of the young
stream are at the headwaters of the older streams because the headwaters
of the older streams are in the forest of the upland w r hile the young
streams are in the unforested and exposed bluff of the lake.

c) Flood-plain communities. — In streams not more than a mile long
we get suggestions of a small flood-plain near the mouth. Here we find
ragweeds and other pioneer plants with their full quota of animals, such
as the plant-bug (Lygus pratensis) and other common insects of rank
pioneer vegetation; willows w T ith their quota of cecropia caterpillars,
viceroy larvae, willow-beetles, etc., are found here as elsewhere. The
flood-plains of such small streams are hardly typical because the streams
are cutting downward so rapidly. They doubtless possess many special
features of interest which are subjects for detailed and special
investigation.

Flood-plain forest is best developed among such streams as the
DesPlaines River and Hickory Creek. As the stream meanders from
side to side of its valley, it presents points of deposition and erosion.
The points of deposition are best for the study of the development of
flood-plain forest.

Girdle of bare sand or gravel (Station 66) : On the wet portions of the
sandy margins one finds the ground beetles (Bembidium) (156), some-
times toadbugs (p. 180), and more rarely the mole cricket. On the
higher and drier portions we have taken the Carolina locust (Dissosteira
Carolina) (40) and the two-lined locust (Melanoplus bivittatus) (40)
hopping over the ground.

Girdle of ragweed and helianthus (sub-formation) (Stations 66, 710;
Table XL VII) : Here (in September) we found several species of spiders,
the meadow grasshopper, long-legged flies, the leaf-hoppers, and the
common plant-bug. This girdle is later displaced by willows.

Willow girdle (sub-formation) (Stations 66, 71a; Table XL VII):
When herbaceous plants have grown for a few years they become mixed
with willows which are inhabited by animals common in low forest mar-
gins. Here (in September) continues the same meadow grasshopper, the
same plant-bug of the earlier stage. Two different spiders are recorded
(Pisaurina and Epeira). From willows along other streams we have

FLOOD-PLAIN FOREST COMMUNITIES iqq v

taken the larvae of the viceroy butterfly (163) and the larvae of the
cecropia moth (Samia cecropia Linn.). Doubtless forest-edge birds
nest here also.

The belt which succeeds the willow is commonly found farther from
the water and has not been so much studied. It is commonly made up
of larger willows, river maples, young elms, young ashes, and small
hawthorns. These are usually much tangled with weeds such as nettles,
and masses of flood trash and vines. General collecting in such a situ-
ation along Thorn Creek (August) secured for us the large green stink-
bug (Nezara hilaris), the spiny assassin-bug (Acholla multispinosa), and
the broad-winged fulgorid (Amphiscepa bivittata). On the maples are
frequently larvae of Symmerista (Fig. 151). On a small hawthorn were
a number of larvae of the handmaid moth (Datana). At this stage the
trees and shrubs become the nesting-places of the yellow warbler and
American goldfinch, which are probably our most characteristic early
flood-plain birds.

In the wet ground of the flood-plain, especially in any small depres-
sions made by overflows, the crayfish (Cambarus diogenes) is the charac-
teristic resident. Under driftwood and on the plants of the water
margin is the slug (Agriolimax campestris), and often also the snails
(Succinea retusa and avara).

Such situations are also the chief haunts of the beaver, which cuts
away the saplings to make its dams. The otter (Lutra canadensis) is
particularly fond of stream margins. It feeds upon crayfishes, fishes,
frogs, etc. It has particular powers of traveling long distances and a
curious habit of sliding down mudbanks and snowbanks for sport (142).
In winter it progresses on ice by repeatedly running a distance and then
sliding as far as the momentum will carry the body. The nest is nearly
always in the stream bank, with the entrance below water. The skunk,
the mink, and the raccoon are also fond of the stream-margin thicket, the
latter picking up fish or crayfish if they can be had at night. This animal
is said to wet its food before devouring it; hence the "waschbar" of the
Germans. The skunk likewise devours almost anything that is to be
had at the water's edge.

d) Flood-plain forest association (Station 68; Table XL VIII). — As
times passes the river cuts lower, the forest develops, and we have
a dense forest of elm, hawthorn, ash, and basswood, with sometimes
walnut and butternut, these being partially displaced on the higher
ground by the oaks. This we may regard as the typical flood-plain
forest.

200

WET FOREST COMMUNITIES

Subterranean-ground stratum: The nymphs of the seventeen-year
cicada and the two-year cicada together with earthworms are always
numerous. The latter comes out on the ground under a log and ascends
under the bark of dead trees during wet weather.

On the ground one finds slugs (Agriolimax campestris). Under
leaves, logs, and bark are snails (Circinaria concava, Polygyra profunda,

Representatives of the Flood-Plain Forest Animal Communities

Fig. 151. — A caterpillar (Symmerista albifrons) on the leaf of the soft maple;
natural size.

Fig. 152. — The common land sowbug (Porcellio rathkei); twice natural size.
Fig. 153. — The scorpion fly (Panorpa venosa); much enlarged.
Fig. 154. — A sphinx caterpillar, from Virginia creeper; natural size.
Fig. 155. — The unicorn larva from dogwood; enlarged.

Pyramidula alternata, and Polygyra clausa, and rarely thyroides). Land
sowbugs are common (Fig. 152). Of the centipedes we note the long
ground form {Geophilus sp.) and sometimes the large millipede (Spiro-

FLOOD-PLAIN FOREST COMMUNITIES

201

bolus marginatus). The white-footed wood-mouse {Peromyscus leucopus
noveboracensis Fisch.) nests usually under a stump or a log though some-
times slightly under ground or in hollow trees (21). The short-tailed
shrew (Blarina brevicauda Say) and the common shrew (Sorex personatus
St. Hil.) are common residents.

In the earlier days (22) the ground stratum was occupied by the
larger mammals. The black bear doubtless found the delicate herbace-
ous plants desirable at certain times of the year. The Virginia deer
occurred here commonly, and the bison and elk invaded the flood-plain
forest in going to the rivers to drink. The timber wolf and the common
fox, both of which formerly frequented
all parts of Illinois, were no doubt also
to be found.

Under fallen logs we find all the
animals that are found on the forest
floor, and some others also. When a
tree first falls to the ground, if it be
still solid or living, the animals which
attack it are the same as those which
attack it when it is standing. If the
tree be an oak or a basswood, one of
the first of these is the weevil (Eupsalis
minuta) (Fig. 156) (155), which bur-
rows into the wood. Later the larvae
of some of the long-horned beetles are
found working under or in the inner

layers of the bark. These are followed by the Tenebrionidae and the
Buprestidae larvae, or flat-headed borers (137). All these tend to let
the water between the trunk and bark, which meanwhile has been
loosening with every rain, then drying, freezing, and thawing, until it
soon becomes quite loose. The space between bark and log is loosely
filled with the castings of the many animals that have worked over the
outer wood and bark, and with wood and bark that have decayed with-
out the aid of these animals. At such a time the space between bark
and log becomes the abode of the flattened larvae of Pyrochroidae,
centipedes, slugs, ground beetles, and nearly all of the small animals
mentioned as belonging to the ground stratum proper. Fallen logs are
also the nesting-places of the weasel {Mustela noveboracensis) (142, 143).

In the autumn we find many hibernating animals under the leaves of
the floor of the flood-plain forest. Here we have found water-striders,

Fig. 156. — An oak borer {Eupsalis
minuta Drury): a, larva; b, pupa;
c, adult female; d, head of adult
male; details of parts are indicated
(after Riley).

202 WET FOREST COMMUNITIES

the cutworms from the field stratum, the stinkbugs and leaf-bugs from
the river margin, and large white-faced hornets (Vespa maculata).

Field stratum: In early summer the forms of the field stratum are
most in evidence. There are scorpion-flies (Fig. 1 53, p. 200), the males of
which have curious clasping organs at the posterior end of the abdomen.
Bittacus, the long-legged insect, closely related to the former, flies about
among the nettles; it has the curious habit of seizing flies with its hinder-
most pair of legs and holding them while they are being devoured. In
their breeding both of these insects belong to the ground stratum.

The harvestmen, or daddy-longlegs, are always in evidence, crawl-
ing over the nettles (Liobunum dorsatum and ventricosum being most
common) . Several spiders (Leucauge hortorum and Theridiumfrondeum)
occur. Numerous bugs including Reduviolus annulatus, syrphus flies
(Syrphus americanus), and aphids, with the various enemies which occur
with them, are common here. After rains we find many animals of the
ground stratum on the nettles and the trunks of trees. We have noted
the slugs (Agriolimax campestris) and the snails (Polygyra profunda and
thyroides) here.

Shrub stratum: The shrub stratum is well developed. The dogwood
is one of the characteristic shrubs, and in early summer its leaves usually
are covered with small bunches of foam which upon inspection are found
to contain a small insect, the spittle insect (Aphrophora). The unicorn
larva (Fig. 155) (163) feeds on the leaves of the dogwood, and the sphinx
larva on the Virginia creeper (Fig. 1540)-

Tree stratum: The tree stratum has not been especially studied.
The trees above the level of the shrub stratum are inhabited by many
borers, lepidopterous larvae feeding on the leaves, and many birds nesting
in the branches. The raccoon is especially fond of nesting high in hollow
trees of the flood-plain forest. The opossum, which was never abundant
near Chicago, found a suitable place in the trees of the flood-plain with
its wild grapes and tender herbs. Under natural conditions this is one
of the chief haunts of the gray squirrel, now familiar in our parks (21).
For birds frequenting the flood-plain, see Baker (100, pp. 476-78).

The most striking peculiarity of the flood-plain forest is its frequent
inundation. In the spring of 1908 we found the flood-plain of the north
branch of the Chicago River inundated at a time when the nettles were
but a few inches high. On the small nettles we found the common small
slug (Agriolimax campestris) and the snails (Succinea avara and retusa) in
great abundance. Caught in a corner behind a tree in some driftwood
we found a carpenter ant (Camponotus), some flood-plain cutworms,

FLOOD-PLAIN FOREST COMMUNITIES 203

crane-fly larvae, and ground beetles. These had been swept into this
position by the current. Wood (21) says that the white-footed mice
and shrews climb the trees when the stream is in flood. As the number
of animals does not seem to be decreased after floods, the animals of the
lower strata of the flood-plain forest must be able to withstand sub-
mergence for days at a time. The fact that these floods come in spring
and winter when the animals are inactive doubtless assists in preserving
them because of the low ebb of their metabolic processes.

e) Succession in the flood-plain forest. — As the stream works over its
flood-plain, it is constantly destroying the forest at some points and
depositing new materials upon which a new series develops at other
points. The depositing sides of the curves present the early forest
stages. Back of these and higher above the stream are the older stages.
Thus the horizontal series which we see when we pass from a depositing
bank across the various terraces is a duplication of the vertical series at
the oldest point or on the highest terrace.

The higher and drier parts of the plain left by the lowering of the river
bed, and much of the flood-plain proper, are often well drained, rarely
flooded, and when thus drained pass rapidly into the oak-hickory type.
At such a stage the oak-hickory animal association is present and the
characteristic flood-plain animals have disappeared.

/) Comparison with other moist forests. — There are a few species
common to the marsh and flood-plain forests. This is true of several
mammals and insects. One of the most characteristic of the insects is
the scorpion-fly. Many of the others belong particularly to the trees
common to the two, such as the ash, elm, basswood, etc.

204

WET FOREST COMMUNITIES
TABLE XLIII

Animals from the Open Pre-Tamarack Bog Dominated by Bulrushes,
Sedges, and Similar Plants

Animals recorded from Tamarack Swamps; M from the swamp at Mineral
Springs, Ind. (Station 54), and P from that near Pistakee Lake, 111. (Station 54a).
Numbers refer to month in which the specimens were taken, f indicates that the
species has been taken from low prairie; * that it has been taken from high.

Common Name

Scientific Name

Habitat

Marsh and
Month

Midge larva

Chironomus sp

Pitcher-plant
a

a

u

a

a
a
a

Pool
a

a

a

a
a

Surface ground
a

«

a

Vegetation
a

u

a

«
a

u

a
a
a
u
a

a
u
a
a
a
a
a
a
a
a
a

M s

Mosquito larva

Caterpillar

M S
M 5

Noctidnae larva

Ground beetle (dead)

A mar a polita Lee

M 5

M 5

*Orb-weaving spider
(dead)

Epeira foliata Koch

* Jumping spider
(dead)

Phidippus podagrosus Htz

Listronotus callosus Lee

Dolichoderus mariae Forel

Helophorus lineatus Say

Planorbis parvus Say

M 5

Snout-beetle (dead) . .
Ant (dead)

M 5
M 5
P 8
P 8

Water-beetle

Flat snail

Crayfish

Cambarus diogenes Gir

M 5

Entomostraca

Snail

M 5
M 5

Snail

Circinaria concava Say

fSpider (Pisauridae) .

Pisaurina undata Htz

M 5

Running spider

Pirata nwntana Em

M 5

fMarsh rattlesnake . .

Ground beetle

Harvestman

Sistrurus catenatns Raf

Platynus picipennis Kirby

Liobunum grande Say

M 5
M S
M s

*Orb-weaving spider. .

Epeira prompta Htz

M 5

f*Orb- weaving spider.

Plectana stellata Htz

M s

fGarden spider

Argiope trifasciata For

P 8

fDictynid

Dictyna sublata Htz

*Crab spider

fCrab spider

Runcinia aleatoria Htz

Tibellus duttoni Htz

P 8
P 8

Jumping spider

Jumping spider

Dendryphantes oclavus Htz

Thiodina puerpera Htz

P 8

M 5

t Orb-weaving spider .
Meadow grasshopper .
Hoosier locust

Eugnatha straminea Em

Orchelimum glaberrimum Burm . .
Paroxya hoosieri Bl

M 5
P 8
P 8

f*Grasshopper (Acri-

didae)

fToad-bug

Bug (Cercopidae)

Bug (fulgorid)

Braconid

Stenobothrus curtipennis Harr

Pelogonus americanus Uhl

Lepyronia quadrangular is Say. . .
Pentagramma vittatifrons Uhler. .

P 8
M 5
P 8
P 8
P 8

Ant

Formica fusca Lin

P 8

Fly (Sciomyzidae) ....

Sepedon pusillus Loew

M 5

Snout-beetle

Baris confinis Lee

M s

Snout-beetle

*Lampyrid beetle ....

Brachybamus electus Germ

Telephones lineola Fab

M 5
M s

Snout-beetle

Listronotus inaequalipennis Boh .

M 5

WET FOREST ANIMALS

205

TABLE XLIV

Animals Recorded from Margin of Tamarack Forest — Forest Edge
Abbreviations as in Table XLIII

Common Name

Spider

Snail

Slug....

Camel cricket

Millipede

Firefly larva

Tortoise beetle

Ground beetle

Tree-frog

Crab spider

Stinkbug

Jumping spider

Orb-weaving spider. .
Orb-weaving spider. .

Katydid

Ant

Pickering's frog

Beetle

Earwig

Brindled locust

Orb- weaving spider. .

Jumping spider

Sawfly larva

Caterpillar

Fly

Spider

Long-bodied spider. .

Harvestman

Jumping spider

Red mite

Ground beetle

Scientific Name

Argiope trifasciata For

Vitrea indentata Say

Agriolimax campestris Binn.

Ceuthophilus sp

Polydesmus sp

Lampyridae sp

Coptocyda bicolor Fab

Pterostichus lacublandus Say .

Hyla versicolor Lee

Philodromus ornatus Bks
Euschistus tri stigmas Say. . .
Dendryphantes militaris Htz.

Epeira trifoliam Htz

Epeira trivittata Key

A. mblycorypha sp

Formica fusca Linn

Hyla pickeringii Hoi

Languria gracilis Newm ....
Apterygida aculeata Scud. . .
Melanoplus punctulatus Scud

Epeira gigas Lea

Dendryphantes militaris Htz.

Nematinae ,

Geometridae

Mesogramma marginata Say
Chiracanthium inclusa Htz . ,
Tetragnatha grallator Htz . . .
Liobunum dorsatum Say ....
Dendryphantes octants Htz. .
Trombidinm sericenm Say . .
Platynus decens Say

Habitat

Ground

Shrubs

Young tamarack

Locality
and Month

P 9
M 5
M 5
M 5
M 5
Ms
M 5
M 5
M 5
M 5
M 5
M 9 P8
P 8
P 8
P 8
M 5
Mo
M 5
Mo
Mo
Mo
M 9
P 8
P 8
M
P
P
P
P

M 5
M 5

2o6

WET FOREST COMMUNITIES

TABLE XLV

Tamarack Forest
For meaning of abbreviations see Table XLIII

Common Name

Scientific Name

Habitat

Locality
and Month

Mosquito

Amphipod

Sowbug

Copepod

Copepod

Copepod

Copepod

Spider (lycosid)

Spider

Millipede

Millipede.

Snail

Slug

Snail

Crane-fly larva . .
Ground beetle . . .
Swamp tree-frog .

Wood-frog

Snail

Ground beetle .
Ground beetle .

Engraver beetle

Engraver destroyer

(larva)

Borer (larva)

Spider

Spider

Spider

Leaf-hopper

Leaf-bug

Tree-hopper

Caterpillar

Beetle (Melandryidae)

Tortoise beetle

Jumping spider

Orb-weaving spider. . .
Orb-weaving spider. . .

Long spider

Jumping spider

Jumping spider

Die tynid spider

Leaf -hopper

Bug

Leaf-bug

Leaf-hopper

Spider

Culex canadensis Theob

Eucrangonyx gracilis Sm

Asellus communis Say

Cantho cam plus northumbricus Br,
Cyclops viridis americanus Mar . .

Cyclops serrulatus Fisch

Cyclops albidus Jurine

Pirata piratica CI

M angora maculata Key

Scytonoms granulatus Say

Polydesmus sp ,

Zonitoides arborens Say

Philomycus carolinensis Bosc.

Circinaria concava Say

Tipulidae

Pterostichus coracinus Newm .

Chorophilus nigritus Lee

Rana sylvatica Lee

Polygyra multilineata var.

algonquinensis Nason

Pterostichus adoxus Say

Pools

Sphagnum
a

Under log and

bark
Under log and

bark
Under log

Pterostichus pennsylvanicus Lee

Polygraphus rufipennis Kirby . .

Thanasimus dubius Fab

Cerambycidae

Epeira ocellata CI

Habrocestum pulex Htz

Theridium frondeum Htz

Gypona striata Burm

Poecilocapsns lineatits Fab.?. . .
Ceresa borealis Fair

Synchroa punctata Newm . . .
Coptocycla clavata Fabr ....

Zygoballus bettini Peck

Epeira gigas Lea

Epeira foliata Koch

Tetragnatha grallator Htz . . .
Dendryphantes octavus Htz. .
Dendryphantes militaris Htz ,

Dictyna foliacea Htz

Cicadula variata Fall

Scaphoideus immistus Say . .

Lygus plagiatus Uhler

Gypona octolineata Say

Pisaurina undata Htz

Under log

Ground under

bark
Ground under

bark
Ground under

bark
Early decay

Decaying wood
a

Under loose bark
Herbs

Undergrowth

M s P8
M 59

M59
M69

M9

M9

M 9

M9

M 9

Mg

M 9

M95
M9

M95
M 9
M9
Mg

M59
P 8

M 5
Mg

M 5 9

M 59
M s 9 P 8

P 8

P 8

P 8

P 8

P 8

P 8

P 8

P 8

P 8

Mg
M59

Mg

M9

Ms

M 5

M 5

M9

M9

WET FOREST ANIMALS
TABLE XLV— Continued

207

Common Name

Scientific Name

Habitat

Locality
and Month

Beetle (Dermestidae)..

Cryptorhopalum haemorrhoidale
Lee

Undergrowth
u

a

a

u

a

a

Low shrubs
a

Shrubs

Mo
M 5
M 5

Beetle (Scarabaeidae)
Lady-beetle

Chalepus nervosa Panz

Psyllobora 20-maculata Say

Cyphon variabilis Thunb

Cyphon padi Linn

Allopoda lutea Hald

Beetle (Dascyllidae) . .
Beetle (Dascyllidae) . .
Beetle (Melandryidae)

Pummice-fly

Ant

M 5
M 5
M 5

Drosophila amoena Loew

Formica fusca Linn

M 5
M 5

Dictynid spider

Spider

Dictyna sublata Htz

Ms
M 5

Hypselistes Jlorens Cam

TABLE XLVI

Animals of the Birch-Maple Belt, Which Succeeds the Tamarack at

Mineral Springs

(Station 54)

Common Name

Scientific Name

Habitat

Month

Red mite

Trombidium sericeum Say

Polygyra albolabris Say

Pterostichus adoxus Say

Phloeotrya quadrimacnlata Say. . .
Listotrophus cingulatus Grav ....

Castianeira cingulala Koch

Xiphydria maculata Say

Rana sylvatica Lee

Ground

a

u
u
u
a
a
a
u

Herbs

a

Shrubs

a
a

u
a

u

a

5

Snail

Ground beetle

Melandryid beetle . . .
Rove beetle

5
5
5
5
5
5
5
5
9

Clubionid spider

Horntail

Wood -frog. . .

Salamander

Plcthodon cinereus Gr

Salamander

Plethodon glutinosus Gr

A gelena naevia Wal

Spider

Tree-frog

Hyla picker ingii Hoi

Phidippus audax Htz

Spider

Spider

5
5
5
5
5

Dendryphantes militaris Htz ....

Misumessns oblongus Keys

Cyphon padi Linn

Spider

Beetle

Beetle

Ant

Photinus corruscus Linn

Camponotus herculeanus ligniper-

dus var. noveboracensis Fitch. .
Calligrapha miiltipunctata var.

bigsbyana Kirby

Leaf-beetle

9

9

208

WET FOREST COMMUNITIES

TABLE XLVII

Animals Occurring in the Ragweed and Willow Thicket Stages of Flood-
Plain Forest Development
(Stations 66, 67, 71a)
Ragweed Stage

Common Name

Scientific Name

Habitat

Month

Snail

Succinea avara Say

Snail

Succinea retusa Lea

Meadow grasshopper.
Tarnished plant-bug. .
Spider

Xiphidium brevipenne Scud

Lygus pratensis Linn

Argiope tr if as data For

Tetragnatha laboriosa Htz

Orchelimum glaberrimum Burm . .

8-9

8-9
8-9

8-9

Long-bodied spider. . .
Meadow grasshopper .

Thicket Stage

Snail

The Succineas above continue
Succinea ovalis Say

Plants

Willow
a

Grape

Weeds and willow

Haw

Willow

Willow
a

u

a

Katydid

Grape scarabaeid ....
Fulgorid bug

Assassin-bug

Spider

Spider

Bythoscopid bug

Sawfly larva

Leaf-beetle

Amblycorypha oblongifolia DeG. .
Pelidnota punctata Lin

Amphiscepa bivittata Say

Lepyronia quadrangular is Say . . .

Acholla muttispinosa DeG

Nezara hilaris Say

Pisaurina undata Htz

Epeira gigas Lea

Idiocerus snowi G. and B

Cimbex americana Lea

Crepidodera helxines Lin

TABLE XLVIII

Animals Usually Common on Herbaceous Vegetation (Chiefly Nettles) of
the Riverside Flood-Plain Forest (Oak-Elm Stage) in June and July
Those starred occur in the corresponding stages of marsh forests.

Common Name

Scientific Name

*Dictynid spider

Dictyna foliacea Htz.

*Spider

Theridium frondeum Htz.
Leucauge hortorum Htz.

Spider (Epeiridae)

*Harvestman

Liobunum dorsatutn Say

*Harvestman

Liobunum ventricosum Wood

False crane-fly

Bittacus strigosus Hag.
Panorpa venosa Westw.

*Scorpion-fly

*Snail

Polygyra thyroides Say (moist days)

Lampyrid beetle >

Podabrus rugulosus Lee.

Long-horned beetle

Strangalia acuminata Oliv.

Click-beetle

Limonius inter stitialis Melsh.

Scarabaeid beetle

Chalepus scapularis Oliv.

Snout-beetle

Rhinoncus pyrrhopus Lee.

Damsel-bug

Reduviolus annulatus Reut.

Capsid bug

Plagiognathus fuscosus Prov.

Fly (Psilidae)

Loxocera pectoralis Loew.

CHAPTER XII

ANIMAL COMMUNITIES OF DRY AND MESOPHYTIC FORESTS

I. Introduction

The forest communities discussed in the preceding chapters are those
displacing aquatic communities. In a climate suitable for forests, trees
spring up on high, well-drained surface materials of all kinds. Forest
appears on rock, sand, clay, etc., first as shrubs or scattered trees, later
as dense mesophytic forest. In the region about Chicago we have forest
in all stages of development and on several kinds of material.

The bluffs of the lake and artificial exposures of clay along the drain-
age canal and the till uplands afford examples of development peculiar
to this type of soil. The few outcrops of Niagara limestone and the
quarries and rock dumps present scattered data on the history of forests
on rock. The extensive sand areas afford examples of all stages of
development peculiar to sand. From all these situations, we find
forests leading toward some type related to climate, either the typical
forest of the forest climate, or the forest of the savanna climate.

II. Forest Communities on Clay
(Fig. 157) (55)

The chief areas of more or less active erosion are along the west side
of the lake, from Waukegan to Winnetka, and on the east side of the
lake from South Haven to Benton Harbor. The old bluffs of the Tolles-
ton and Calumet stages as represented north of Waukegan and at
various other points offer valuable areas for comparison. There are
also similar bluffs along many of our streams, some of those in Michigan
being very old.

When the ice sheet receded entirely and left the outline of Lake
Michigan much as it is now, doubtless the shore presented a more or less
rounded profile. However, since that time waves have gradually
changed the shore profile. By washing away the clay at the base of
such a shore, a bluff has been developed (62).

I. STEEP BLUFF ASSOCIATION

(Station 56; Table XLIX)
a) Ground stratum (55) (Fig. 157). — In spring, when the frost goes out
of the ground, leaving the clay somewhat loosened, the ground-water

209

2IO

DRY AND MESOPHYTIC FOREST COMMUNITIES

level is high, and gravitation overcomes the viscosity of the clay, and
great masses, whose consistency is that of thick mud, slump down in the
form of landslides. This process naturally decreases the angle of slope at
the points where the slumping takes place. Slumping does not occur
equally everywhere and the bank becomes very irregular. Under such
conditions the only animals present are the Collembola. In summer the
steep bank dries. No animals are present as actual residents. The
bank serves only as a casual alighting-place for tiger-beetles, butterflies,
bees, flies, and other insects. Few or no plants are present.

Fig. 157. — Upper figure is a
diagram showing Lake Michigan
bluff as seen from the zenith.
U, level surface of upland; BL,
bluff; SB, sandy beach; M,
water of Lake Michigan; J,
piers; toward the left is north;
sand has lodged on the north side
of the piers. AB and CD indi-
cate positions of cross-sections
below. Middle figure is a cross-
section AB. Slumping bluff
stage. The adults of Cicindela
limbalis are distributed from A
toB; the larvae, sparingly, from
E to F. Other letters as in the
upper figure. Lower figure is a
cross-section CD; stage of some
bluff stability and bare clay
exposure. Adults of limbalis
between C and D; larvae plenti-
ful between G and H. Other
letters as above. Reprinted
from the Journal of Morphology.

Unless something interferes with the action of the waves the same
series of events just described continues from year to year. If for some
reason the action of the waves is checked, the associated processes will
be checked also. At various points along the shore piers have been built
out into the water at right angles to the shore for a distance of a hundred
meters or more (Fig. 157). The currents in the lake are southerly in
direction along the west shore. Whenever water in motion, laden
with material picked up by its action against the bluff, strikes one of
these piers, its velocity is decreased and a part of the material is dropped

ON CLAY

211

on the north side of the jetty. Materials thus deposited gradually
pile up to such an extent as to protect the base of the cliff from
wave-action. Thus the effect of the slumping of the springtime
(which tends to reduce the angle of slope) is not fully removed from
year to year.

d

Fig. 158. — The bluff habitats near Glencoe, 111., showing several stages in the
development of the forest on the bluff. The area to the right of a line between a and b
is stable enough to support some sweet clover. Here the tiger-beetle larvae, spider,
etc., are most abundant. The area between lines joining a and b and a and c is in the
early shrub stage. To the left of ac the shrubs are denser and larger, and some trees
are present. Reprinted from the Journal of Morphology.

2. SWEET-CLOVER ASSOCIATION

(Fig. 158) (55)
Under the condition described above, the water of rainfall, as well
as the slumping, reduces the angle of slope, and the bluff becomes more
and more stable. Some of the clods of turf from the top of the bank
stop half way down the slope. The bluff begins to support a few xero-
phytic plants, such as the sweet clover, asters, etc.

212

DRY AND MESOPHYTIC FOREST COMMUNITIES

vAfeA/

162

163

Life History of the Clay-Bank Tiger Beetle
(Reprinted from the Journal of Morphology)

Fig. 159. — From left to right — the ventral, side, and dorsal view of the oviposi-
tor of the bluff tiger-beetle {Cicindela limbalis) with segments numbered; 3 times
natural size.

Fig. 160. — The egg of the same in the hole in the ground made by the ovi-
positor; 1 \ times natural size.

Fig. 161.— The egg; $h times natural size.

Fig. 162. — The larva, side view; h, hooks; 3 times natural size.

Fig. 163. — The anterior half of the larva: an, antennae; mp, maxillary palp;
m, mandible; 0, ocelli; 3 times natural size.

Fig. 164.— The pupa; 3 times natural size.

Fig. 165. — The burrow of C. limbalis, pupal cell; \ natural size.

ON CLAY

213

a) Subterranean-ground stratum. — Perhaps the most characteristic
animal of the steep bluff is the bluff tiger-beetle (55, 151) (Cicindela
purpurea limbalis) (Figs. 159-67). In the open places of this stage, the
larvae, which live in curved cylindrical burrows (Figs. 165, 166), are
common.

The female beetle is provided with an ovipositor (Fig. 159) adapted
to making small holes in the clay in which eggs are laid (Figs. 160, 161).

ft.&

' t ,"J&

66

168

&

69

Clay-Bank Inhabitants
Fig. 166. — View of larval burrow of the tiger-beetle; natural size.
Fig. 167.— The adult tiger-beetle {Cicindela limbalis); about twice natural size.
Fig. 168.— The clay-bank spider (Pardosa lapidicina).
Fig. 169.— A snail of the shrub stage (Polygyra monodon); enlarged.
Fig. 170. — The snail (Polygyra thyroides) ; enlarged.

The larva (Figs. 162, 163) on hatching from the egg digs a burrow in the
position of the ovipositor hole. The eggs, which are laid in June, hatch
in two weeks and the larvae live in the spot where the eggs were laid
for one year, and transform into pupae (Fig. 164) in the ground in an
especially prepared cavity (Fig. 165). The adult, which is a reddish-

214 DRY AND MESOPHYTIC FOREST COMMUNITIES

green form (Fig. 167), appears in the autumn and lives over winter in
the ground (151).

The tiger-beetle larvae are found on the bare spots and sometimes
among the sweet clover (eggs are laid before the clover is full grown).
They feed on any animals that crawl over the clay within reach — any
that w r e mentioned may fall victims.

As physiographic processes go on, we find that more animals make
their appearance, bristle-tails creep out of the cracks in early spring, and
occasional slugs and geophilids are found hiding under clods. A large
black spider (Pardosa lapidicina) (138) (Fig. 168) and many smaller
species are present also. More rarely one of the land snails {Pyramidula)
is present at this time of year, crawling about under the dead vegetation.
The mud-dauber wasp (Pelopoeus cementarius) secures its mud (40)
and the Carolina locust (Dissosteira Carolina) probably breeds here.

b) Field stratum. — Under such conditions, as summer advances the
sweet clover grows up, and as soon as it is of considerable size it is
attacked by aphids, which form the basis for a small consocies of inter-
dependent animals. Many coccinelids come to feed on aphids, and
parts of adult coccinelids have been found in the burrow r s of the tiger-
beetle larvae. The golden-eyed lacewing (Chrysopa oculata) deposits
stalked (p. 291) eggs on the plant; soon its larvae — the aphis-lions —
are devouring aphids, as do also the larvae of syrphus flies (164).

Crab-spiders (Runicina aleatoria, Misumena vatia) (138) lie in wait
in the clover flowers and thus capture the nectar- and pollen-seeking
flies, such as Eristalis tenax (Fig. 271, p. 270) and Syrphus ribesii Lin.
(165). The common plant-bug (Adelphocoris rapidus) (Fig. 262, p. 266)
is especially abundant in autumn. The honey-bee {Apis mellifera) and
a bumblebee (Bonibus americanorum) come in numbers for nectar and
pollen. Grasshoppers, such as Scudderia, Melanoplus Jemur-rubrurn,
etc., are common, and when young may fall prey to spiders such as orb-
weavers (Epeira trivittata). Parasitic hymenoptera (Pitnpla conquisitor
Say) are also common.

3. SHRUBS ASSOCIATION (a FOREST MARGIN SUB-FORMATION)

A little humus accumulates locally through the decay of sweet
clover. The roots of plants in the soil and the undecayed trunks of
the sweet clover hold this and the mineral soil in place against the
action of the rain as it falls on the slope. Conditions become ripe
for the germination of the seeds of other plants and for the breeding
of other animals. Shrubs, such as the willow and shad-bush, appear

ON CLAY 215

as scattered individuals here and there, and bring with them new
conditions and animal forms.

a) The subterranean- ground stratum. — In addition to Pyramidula
mentioned above, other snails appear, especially in the more moist spots
on the bank. These are Zonitoides, Polygyra monodon (Fig. 169),
and P. thyroides (Fig. 170). Centipedes (Geophilus) and millipedes
(Polydesmidae) become more numerous, while the spiders (Pardosa
lapidicina) (Fig. 168), the tiger-beetle larvae, and other soil-inhabiting
forms decrease.

b) Field stratum. — The field stratum of the shrub stage does not
differ strikingly from the preceding, as it consists mainly of plants of
the earlier stage scattered among the shrubs.

c) Shrub stratum. — Here we have the characteristic inhabitants of
shrubs. On the young aspens and willow are the larvae of the viceroy
butterfly (163). The common gall on the willow is the pine-cone gall,
caused by Cecldomyiidae (137). Beneath the leaves of the cone we have
found long slender eggs of some orthopterous insect (probably Xiphidium
ensiferum) (40, p. 428). We have no record of the nests of birds, but
many of the forest margin birds nest here (see pp. 274-75 and Table
LXIV, p. 277).

4. YOUNG FOREST STAGE

(Fig. 171)

Shrubs and seedlings of trees become more and more numerous.
The sweet clover and most of the animals associated with it disappear.
Young trees, such as oak, hickory, hop hornbeam, etc., grow and usually
give rise to a sapling forest.

a) Subterranean- ground stratum. — This stratum has all the characters
of the more dense and mesophytic forest ground stratum and largely be-
cause of the springy character of the bluff which supplies much moisture.
The woodchuck (Marmota monax) (142) sometimes digs in these banks.
In the open places in which small areas of soil are covered with only a
few leaves we find the larvae of the green forest tiger-beetle (Cicindela
sexguttata) (55, 151) which lays eggs in shaded places (Figs. 172, 173).
Under the leaves the snails, which were recorded in the younger stages,
and sowbugs are present. We find snails and slugs {Polygyra profunda
[Fig. 220, p. 237] and albolabris [Fig. 240, p. 243], Philomycus caro-
linensis [Fig. 231, p. 241]), which are commonly abundant in dense
woods. The Myriopoda are also more numerous and belong to different
species. Fontaria corrugate (Fig. 218, p. 237), which has the margins

2l6

DRY AND MESOPHYTIC FOREST COMMUNITIES

The Bluff Forest

Fig. 171. — An open place in the oak and hickory forest of a Tennessee mountain-
side, a typical green tiger-beetle (Cicindela sexguttata) habitat. The individuals were
seen copulating on the log in the foreground. The general aspect is very similar to
that of the bluff forest. (Reprinted from the Journal of Morphology.)

172 173

Fig. 172. — The black dots represent the distribution of the larvae of C. sexguttata
from eggs laid in a cage. The larvae are in the exact position in which eggs are laid.
The stippled area is in shadow in the middle of the day.

Fig. 173. — Diagram of a burrow of Cicindela sexguttata.

ON ROCK

217

of the segments striped with yellow, is one of the most characteristic
of moist woods, while others {Geophilus rubens and Lysiopetalum lac-
tarium) are not uncommon. Ground beetles (Calathus gregarius Say)
and bugs (Reduviolus subcoleoptratus) occur. In logs of fallen basswood
we found the larvae of Tenebrionidae and Cerambycidae and of horntails,
the burrowing hymenoptera, and the Mycetophilidae larvae (Sciara)
(Fig. 174) (165).

c) Field stratum and shrub stratum. — The field stratum has been but
little studied. We have taken a few Scudderia nymphs, some spiders,
and bugs, but no adequate study has been carried on.

d) Tree stratum. — This has likewise been but little studied, but in
these young forests, while the ground stratum is like that in the older
forest, the tree stratum is poorly de-
veloped because the trees are short
saplings. As time goes on, however,
the forest becomes more dense. Such
a forest may be seen on the bluff at
Lake Bluff, 111.

5. OTHER BARE CLAY FORESTS

Other bare clay young forests may
be seen along the dumps of the drainage
and Chicago-Michigan canals at Summit.
Here we find practically the same stages
as at Glencoe on the lake bluff. There
are the steep clay bluffs with no perma-
nent residents, the semi-stable bluffs, or
weed-occupied areas. These are like the
semi-stable bluffs at Glencoe but the tiger-beetle is another species and
selects more nearly level places; otherwise it is very similar in habits.

The shrub stage occurs but is without the snails, since the ground-
water level is lower and the moisture in the soil of the lake bluff is wanting
here. This causes the development of the ground stratum to lag behind,
while it is in advance in the bluff forests. Accordingly we find a sapling
forest made up largely of cottonwoods. This has not been studied.

Fig. 174. — One of the fungus
gnats {Sciara sp.) the larvae of
which are commonly found under
the bark of trees, feeding on fungus.

III. Forest Communities on Rock
(Station 55)
The rock exposures near Chicago are not numerous, and we have
studied only those at Stony Island. There the bare rock is inhabited

2l8 DRY AND MESOPHYTIC FOREST COMMUNITIES

by incidental forms, such as the Carolina locust (Dissosteira Carolina ?)
(40), with occasionally the red-legged locust {Melanoplus femur-
rubrum) and the two-lined locust {Melanoplus bivittatus). Under rock
fragments we took the ground beetle {Anisodactylus inter punctatus) and
the common cricket {Gryllus pennsylvanicus) . Hancock (40) states
that the smooth cockroach (Jschnoptera inaequalis Sauss) and the large
cockroach (/. major Sauss) occur in such situations. We found the nest
of a spider (Agelena naevia) attached to one of the loose rocks.

Other stages have been studied only superficially. In the cracks
and crevices of rocks and rock piles, shrubs and vines grow and the
young forest, field, and shrub strata have all the appearance of the
shrub stage on clay at Glencoe. The animals are for the most part those
common to thickets.

IV. Forest Communities on Sand

In chap, iii, pp. 46, 47, we discussed sand areas and their distribu-
tion. In chap, viii we noted the series of ponds and ridges with a little
regarding their origin (pp. 136-40). Their general relations are indicated
by Figs. 83, p. 137, and 84, p. 139. It appears that the margin of the lake
may, under conditions of rapid recession, become the margin of an inland
pond. Under condition of slower recession this belt may be buried and
hence come to lie beneath such belts as lie farther inland. Since the
sand areas about Chicago represent all the stages in the development
of forests, beginning with the bare sand and ending with the beech
forest, it is my purpose in the remainder of this chapter to follow the
animal associations and formations of forest development. Some of the
stages will be taken from till areas, but this is because these stages are
more extensive than the corresponding stages on the sand deposits.

The chief stages are the wet sand of the water margin, the middle
beach, the cottonwoods, the old cottonwoods and pine seedlings, the
pines, the black oak, the black oak and white oak, the black oak-white
oak-red oak, the red oak-white oak-hickory, the basswood-red oak-
white oak-maple in moister places, and the beech and maple.

I. THE WATER MARGIN ASSOCIATION

(Stations 56, 58; Table XXXVIII)

One morning early in June, we walked along the beach of Lake

Michigan for a mile and a half, for the particular purpose of studying

the animals of the zone within the reach of waves. Animals were few,

only stragglers of the regular residents which we have noted on p. 181.

WATER MARGIN

219

The day was warm and a strong southeast wind was blowing. In mid-
afternoon there was a small shower and the wind changed to a strong
northeaster. At 4 p.m. we paid another visit to the beach. The waves
were rolling moderately high and the beach was covered with a host of
insects, chiefly alive, though many were dead. The beach was lined
with live forms crawling away from the water. Often the live ones
were still clinging to small sticks upon which they had floated ashore
by the fifties. These insects represented all orders, belonging to various
habitats near the lake. There were large forest margin bugs, potato-
beetles, lady-beetles, horseflies, robber-flies, butterflies, water, marsh,
prairie, and forest inhabitants which had been blown in the lake in the
forenoon. With them were occasional fish, some with large round scars
showing the work of the lampreys (166); others that had evidently died
from other causes. On other occasions dead muskrats, dogs, cats, birds
of all kinds have been found in these lines of drift (167). On one
occasion, birds, chiefly downy woodpeckers, were so numerous that
one could almost step from one to the other, had they been equally
spaced over the half-mile of beach upon which they were strewn. Need-
ham (168) has studied the drift and gives an account of the numerous
beetles that came ashore.

In a few days after such a storm, one finds the various insects that
washed ashore either lying dead, or alive under the chips, sticks, and
carcasses which came with them. Flesh-flies detect the presence of the
food very quickly, and often come to dead fish inside of ten or fifteen
minutes (169). These flies belong to the families Sarcophagidae and
Muscidae. As a result of storms which float the bodies of animals
ashore from time to time, the flies always find a sufficient quantity of
decaying flesh to maintain the species. The flies are in competition with
a large number of scavenger beetles: e.g., a hister (Saprinus patruelis
Lee.) which feeds on carrion (Stereopalpus badiipennis Lee). Several
species of rove-beetle complete a partial list of the other scavengers
usually more or less abundant on the shore. The larvae of Dermestidae
have been found under the dry remains of fish which had been worked
over by the carrion-feeders.

Preying upon these and upon the insects that come ashore are the
tiger-beetles (Cicindela hirticollis and cuprascens) (151, 170) which pick
up the flies that they often are able to seize while alighting on the ground.
They also capture the maggots of the flies when they leave the carrion,
and the lady-beetles and other small insects which come ashore. Several
species of the ground beetles and occasional shore bugs (Saldidae) are

220 DRY AND MESOPHYTIC FOREST COMMUNITIES

found, while the digger-wasps and robber-flies of the beach farther back
come here for flies and other prey. The spotted sandpiper picks
maggots from the bodies of dead fishes. Mr. I. B. Myers states that
skunks visit the beach in the night and feed upon the drift.

2. MIDDLE BEACH ASSOCIATION

(Stations 57, 58, 716) (Fig. 175)

The belt within the reach of ordinary waves is usually wet. The
belt a little higher up, farther from the shore, is characterized by more
permanent residents. From the often wet margin to the first cotton-
woods is the middle beach (Fig. 175).

This middle beach is usually dry in summer but is reached by the
waves of severe storms and often covered by snow and ice to great
depths during the winter. It is the final lodging-place for the driftwood
which stops temporarily farther out. This belt arises in the place of
the preceding through the latter being buried by the deposition of
sand. In digging into the sand here or elsewhere one usually encounters
wood and other traces of organic matter.

. a) Subterranean-ground stratum. — In the lower places where the
ground is usually moist, we find the larvae of Cicindela hirticollis (170)
which live in straight cylindrical vertical burrows about 6 in. deep. On
higher ground, where there is the beginning of the incipient dunes, are
the occasional larvae of the white tiger-beetle {Cicindela lepida) and the
burrowing spider (Geolycosa pikei), which has a burrow similar to the
tiger-beetles, but larger, and always distinguished by the presence of a
tubular web at the entrance. Burrowing beneath the sand is the white
carabid (Geopinus incrassatusDe].) and termites or white ants. The latter

Inhabitants of the Middle Beach

Fig. 175. — General view showing the line of cottonwoods and the scattered
driftwood.

Fig. 176. — The larva of one of the cabbage butterflies {Pieris protodice Bd.);
found on sea rocket; much enlarged.

Fig. 177. — Pupa of the same.

Fig. 178. — A log on the beach; favorite habitat of the termites {Termesflavipes).

Fig. 179. — Termites; a, queen; b, nymph of young female; c, worker; d, soldier
twice natural size (after Howard and Marlatt, Bidl. 4, Div. EnL, U.S. D. Agr).

Fig. 180. — The older cottonwoods of the cottonwood belt.

Fig. 181.— The adult white tiger-beetle {Cicindela lepida); twice natural size.

Fig. 182.— The burrow of the larva of the white tiger-beetle.

MIDDLE BEACH

221

intiiirfcrfriin

75

78

Mr.

1 180

1 I

* 179

^ I.

181

r >,. i . _ i . .-.:..■:

1182

Inhabitants of the Middle Beach

222 DRY AND MESOPHYTIC FOREST COMMUNITIES

feed on decaying wood (Fig. 178) and make their way to the under side
of wood lying on the beach (Fig. 179). The bank swallow often nests
in the sides of vertical sandbanks. Under the driftwood we find the
scavengers and predatory species of the preceding belt. They spend
their time here when the beach is not well covered with food. The
sand-colored spider (Trochosa cinerea) (138) is a regular resident. The
common toad finds shelter beneath the driftwood during the day, going
forth in search of food at night. After sleeping near the beach one night
we found the sand about where we had lain crossed and recrossed by the
tracks of the toads and other smaller animals, such as beetles, spiders,
etc. The toad finds food abundant near the shore. The white-footed
mouse occasionally nests here under the largest driftwood. The spotted
sandpiper and piping plover nest here occasionally.

b) Field stratum. — There are occasionally very young seedling
cottonwoods. Sea rockets and some other plants grow in this belt.
Occasionally we find the larvae of a cabbage butterfly {Pieris protodice
Bdv.) (171) on the sea rocket (Figs. 176, 177). There is no shrub or
tree stratum.

3. THE WHITE TIGER-BEETLE OR COTTONWOOD ASSOCIATION

(Stations 57, 58, 59; Tables L, LVI, LVII)
(Fig. 180) (115)

This begins with the line of young cottonwoods which we see in
Fig. 175. The beach belt sometimes overlaps it because the large
driftwood is sometimes mixed with the cottonwoods. The cottonwood
belt is underlaid by the two preceding, and has succeeded them.

a) Subterranean-ground stratum. — Here the white tiger-beetles (Figs.
181, 182) reach their maximum abundance and the openings of their
cylindrical burrows are numerous; the termites continue wherever there
is wood for them to feed upon; the burrowing spider is commoner
here than in the preceding zone (172). This is pre-eminently the zone
of digger-wasps (173). Here the holes of Microbembex monodonta
(Fig. 183) are numerous. This species is somewhat gregarious, the bur-
rows usually being in groups. They probably store their nests with flies
secured often from the beach. Another larger bembex (Figs. 184, 185)
(B. spinolae) also stores its nest with flies. Anoplius divisus, the
black digger, stores its nest with spiders. The velvet ant (Mutilla
ornativentris) is present. Dielis plumipes appears in May and lays its
eggs in the sand.

The robber-flies (Erax) (Fig. 186) (165) (Promachus vertebratus) (Fig.
187) are common; their larvae live in the sand as parasites on other

COTTONWOOD ASSOCIATION

223

species. Some bee-flies (Exoprospa) (Fig. 188) lay their eggs at the
entrances of the burrows of Microbembex. The roots of the beach grasses
are probably attacked by the larvae of snout-beetles (Sphenophorus)
(Fig. 189) (174) of which several species are very common in the vicinity.
The white grasshopper {T rimer otro pis maritima) (40) and the white tiger-
beetle (Cicindela lepida) are most characteristic. The long-horned
locust (Psinidia fenestralis) (Fig. 189) occurs commonly.

b) Field stratum. — The field stratum is made up of animals that
occupy the grasses, sagebrush, and a few other xerophytes. Animals

Digger- Wasps of the Cottonwood or White Tiger-Beetle Association

Fig. 183. — Photograph of a number of the burrows of one of the digger-wasps
{Microbembex monodonta) at Pine, Ind.

Fig. 184. — A digger-wasp {Bembex spinolae)) about twice natural size.

Fig. 185. — A sectional drawing of a burrow of the digger-wasp {Bembex spinolae);
reduced (after the Peckhams, Wis. Geol. and N. H. Surv.).

are few. An occasional red-legged locust (Melanoplus femur-rubrum)
occurs here. Midges, mosquitoes, and the flies which breed on the beach
rest on the leeward side of the grasses (169). Various native sparrows
are common in fall, feeding on grass and weed seeds.

c) Shrub stratum. — On the young cottonwoods we find the crab-
spider (Philodromus alaskensis), often with its appendages stretched out
on the petiole or midrib of a leaf. The animals feeding on the cotton-
wood here are few. In early spring the willow blossoms are frequented

224

DRY AND MESOPHYTIC FOREST COMMUNITIES

by pollen-gathering insects (Andrenidae, Apidae, syrphus flies, etc.).
The kingbirds feed on these insects; one article of their diet, the robber-
flies, is always common. A chrysomelid beetle (Disonycha quinquevittata)
commonly feeds upon the willow. The cherry is attacked by aphids

Fig. 186. — A robber-fly (Erax sp.); 3 times natural size (after Williston).

Fig. 187. — Robber-fly {Pro-
tnachus vertebratus Say); natural
size (after Washburn from Willis-
ton).

Fig. 188. — A bee-fly {Exoprosopa
sp.); 1 2 times natural size (from
Williston after Kellogg).

which attract the Coccinellidae, and the syrphus flies. Cherries are
eaten by many birds.

COTTONWOOD ASSOCIATION

225

d) Tree stratum. — The cottonwood is attacked by many borers.
The most characteristic is Pledrodera scalator, which is not common.
There are few leaf-feeders excepting two gall aphids; the petiole gall is
due to the work of Pemphigus populicaulis, and the terminal gall to
Pemphigus vagabundus (137). These occur on the cottonwoods along
the lake rarely, being more abundant farther inland, where they are
protected from the severity of winter. The osprey nests in trees, and the
tree-swallow in the dead ones.

We have noted that this association often arises through the burying
of the preceding one. Deposition of
sand is the chief cause of succession
up to this point. When cottonwoods
and grasses begin to grow and digger-
wasps begin to burrow, organic mat-
ter is continually added to the soil.
The grasses die down from time to
time, the roots and leaves of the
shrubs and other plants add humus.
The myriads of digger-wasps which
go elsewhere (probably commonly to
the beach) for the animals with which
to store their nests add a large amount
of organic matter at a depth of a few
inches. The grasses bind the dune
sand; the conditions become favorable for other plants,
stage the bunch-grass and seedlings of pines appear.

Fig. 189. — The long-horned locust
(Psinidia fenestralis) (after Lugger).

At such a

4. TRANSITION BELT

(Station 58; Table L) (Fig. 190) (115, 170)

The stage of mixed pine seedlings, old cottonwoods, and the begin-
ning of the bunch-grass constitutes a well-marked belt. Along the
shore, from Indiana Harbor to Gary, there was formerly a ridge upon
which the lakeward-facing side supported the typical community of the
cottonwoods and the landward side the transitional belt. When one
crosses to the landward side of such a ridge he notes a change in the
animals. The white tiger-beetles and the maritime grasshopper are
practically absent. Digger-wasps are abundant. The larvae of the
large tiger-beetle {Cicindela formosa generosa) (Figs. 191-193) with their
pits and crooked holes are added, but they rarely invade the dense pine
areas. Another grasshopper (Fig. 194) (Melanoplus atlanis) and an

226 DRY AND MESOPHYTIC FOREST COMMUNITIES

Fig. 190. — The cottonwood and young pine area at Buffington, Ind.
Fig. 191. — The burrow of one of the tiger-beetles resident here.
Fig. 192. — The same opened, showing the stove-pipe form of burrow opening
into the side of the pit shown in Fig. 191.

Fig. 193. — The adult beetle (Cicindela formosa generosa).

PINE ASSOCIATION 227

occasional M. angustipennis are added (40). The burrowing spider
(Geolycosa pikei) (Fig. 200, p. 230) continues in the open places.

5. THE CICINDELA LECONTEI OR PINE ASSOCIATION

(Stations 57, 58, 59; Tables L, LI, LVI, LVIII) (Figs. 201) (115, 170)
a) Subterranean- ground stratum. — Here we find the larva of the
bronze tiger-beetle (Cicindela scuiellaris lecontei) (170), with its straight,
cylindrical burrow. Several digger-wasps of the earlier stage are
recorded as continuing. The ant (Lasius niger americanus) nests
beneath the sand and was seen swarming in early September. The
burrowing spider continues and an occasional cicada lives deep beneath
the sand. The six-lined lizard (Cnemidophorus 6-lineatus), the blue
racer, and the pond turtle (Chrysemys marginatd) all bury their eggs
beneath the sand. There is an occasional thirteen-lined ground squirrel

1 1

Fig. 194. — The lesser migratory locust (Melanoplus atlanis) (after Lugger) .

[Citellus ij-lineatus) (162), though it is never common. The surface
of the ground is frequented by the adults of the tiger-beetles, digger-
wasps, the six-lined lizard, and the blue racer (157). The grasshopper
of the transition belt continues and two others are added, so that we
have the long-horned locust, the narrow-winged locust, the lesser locust,
the mottled sand-locust (Sparagemon wyomingianum Thorn.), and sand-
locust [Ageneotettix arenosus) (40). The ruffed grouse nests here occa-
sionally.

b) Field stratum. — Arabis lyrata is a common herb. Shull (175)
found that the larva of a cabbage butterfly feeds upon this. He
watched a larva crawl on one of the bunches of bunch-grass for six
hours before it began to spin the bed of silk preparatory to pupating.
This was about 2 in. above the ground. Midges and mosquitoes are
common and dragon- and damsel-flies are nearly always in evidence
resting on the grasses and herbs and picking up the midges and mos-
quitoes while on the w T ing. Occasional Monardas support crab-spiders
which resemble the blossoms closely (Dictyna foliacea). The flowers
are visited by bees and flies.

22c

DRY AND MESOPHYTIC FOREST COMMUNITIES

c) Shrub stratum. — Here we have the young pines, the juniper, and
the willows. From the evergreens we secured several spiders (Philo-
dromits alaskensis, Dendryphantes octavus, Theridium spirale, and
Xysticus formosus) (172), and with them sometimes an assassin-bug
(Diplodius luridus). On the willows are some characteristic willow-
feeders, but they appear to prefer the more mesophytic depression
shrubs.

Inhabitants of the Pine

Fig. 195. — The nest of the kingbird (Tyrannies tyrannus Linn) in a pine tree.
The nest is made from the string of a fisherman's net.

Fig. 196. — The pitch mass of the pitch-moth (Evetria comstockiana ?) ; twice
natural size.

Fig. 197. — The larva removed from the mass.

Fig. 198. — The larva of the pine engraver beetle (Ips grandicollis); much
enlarged.

Fig. 199. — The adult of the same, from Pinus banksiana.

d) Tree stratum. — The pine is attacked by many borers and few
leaf-feeders. Of the borers several broad-headed grubs have been taken.
The bark beetle (Ips [Tomicus] grandicollis) (Figs. 198, 199) (137) is
common under the bark of dead and dying trees, especially on the north
side, where the trees stand unprotected. The twigs are attacked by the

BLACK-OAK ASSOCIATION 229

pitch-moth (Evetria comstockiana?) (Figs. 196, 197) (137) which feeds
on the new shoots, covering itself with a tent made of pitch and its own
excreta. About the bases of the needles, or where pitch is exuding, we
often find small larvae resembling Cecidomyiidae fly larvae, but we have
found no pitch-midges, chrysomelid flea-beetles, spittle insects, or other
enemy of the eastern hard pines which grow in thicker stands. More
careful study of these trees at frequent intervals throughout the grow-
ing season would probably greatly increase the list of both borers and
leaf-feeders.

The hairy and downy woodpeckers nest in the hollow trees. Their
deserted holes are later used by the black-capped chickadee and the
screech owl. Farther north the pine grossbeak and crossbill nest in the
live pines. The golden-crowned kinglet and the black-throated, green,
and pine warblers are abundant here during the migration period. They
nest in the pines farther north, and, according to Butler (108), not infre-
quently at the head of Lake Michigan. Dr. Stephens photographed a
kingbird's nest made from cord from a fisherman's net (Fig. 195).

The pines prepare the way for the oaks, which appear first as seed-
lings, usually becoming more dense with time and finally crowding out
the pines.

Moving dunes and "blowouts" (depressions in the sand made by
wind) are common at the head of Lake Michigan. The latter vary
from a few feet square and a few inches in depth to some scores of feet
n depth and diameter. Dunes, hundreds of feet high, move from place
to place. On these the bare-sand conditions of the Cottonwood and pine
associations occur in areas generally dominated by black oak. Here con-
tinue the animals of these two belts, with the possible exception of the
maritime locust. The typical black-oak forest always possesses these
" blowouts,' ' but surrounding them and under the trees we note the
typical herbaceous and shrub growth, and it is with this and the oaks
that we are next concerned.

6. THE ANT-LION OR BLACK-OAK ASSOCIATION

(Stations 57, 60, 61, 62; Tables L, LIT, LVI, LIX)
(Fig. 202) (115, 170, 176)
Among the black oaks are open spots of relatively stable sand.
These small areas may possess some of the same species as the pine areas,
but other species give them individual character. In the black-oak
stage proper, bare sand is limited. The bronze tiger-beetle (Cicindela
scutellaris lecontei) (Fig. 204) which is parasitized by the larva of a bee-
fly (Spogostylum anale) (Fig. 205) is abundant (151a.)

230 DRY AND MESOPHYTIC FOREST COMMUNITIES

Representatives of the Pine and Black-Oak Association

Fig. 200. — The burrow of a ground spider (Geolycosa pikei) ; about natural size.
Fig. 201. — General view in the pines. Fig. 202. — General view among the oaks.
Fig. 203. — The ant-lion and the pupa and adult into which it transforms.
Fig. 204. — The opening of the burrow of the bronze tiger-beetle (Cicindela
scutellaris lecontei) ; natural size.

Fig. 205. — The bee-fly (Spogostylum anale); twice natural size.

BLACK-OAK ASSOCIATION

231

a) Subterranean-ground stratum. — Several digger-wasps and para-
sites not found in the earlier stages occur among the more closely placed
vegetation here (Epeolus pusillus, a parasite, Specodes dichroa, and Ody-
nerus anormis). A megachilid or leaf-cutter makes a nicely matched
thimble-shaped cell. This cell is placed at the end of a burrow about
2 in. below the surface of the sand. The burrow is about 4 in. long. The
leaf-cutter is attacked by a parasitic bee (Coeloixys rufitarsus) which
lays its eggs upon the larval cell. One sunny day we found the digger-
wasp (Ammophila procera) (173) with a black-oak caterpillar {Nadata

206
Representatives of the Black-Oak Community

Fig. 206. — One of the solitary wasps (Ammophila procera), with the oak-feeding
larva (Nadata gibbosa), which it has carried to a point near its nest and laid upon the
ground; i\ times natural size.

Fig. 207. — Female crab spider (Misumessus asperatus) (after Emerton) ; enlarged.

Fig. 208. — Male of same.

Figs. 209a, 2096. — The flatbug (Neurodenus simplex) which lives under the bark
on the dead oaks. 209a is a side view, much enlarged.

gibbosa) (Fig. 206) (137). When first observed, the larva was lying on
the ground and the wasp was moving about some 6 in. away. As we
approached, the Ammophila, apparently disturbed, seized the large
caterpillar and ran into the adjoining vegetation, where it was captured.
All the forms mentioned as breeding beneath sand, feed at the surface
of the soil or upon the vegetation. In open places among the black
oak we find the same grasshoppers as in the earlier stages. The hog-nosed
snake (40) is common; it spreads and flattens out its head when dis-
turbed; when handled roughly it often goes into a death feint, such as
the oriental snake-charmers produce in their poisonous snakes by pres-

232

DRY AND MESOPHYTIC FOREST COMMUNITIES

sure on the back of the neck. In this state it can be handled as if dead,
laid in any position, or tied into a knot. The only movement it persists
in making is that of turning its ventral side uppermost. Ant-lions (Fig.
203) are very rarely found at the south end of Lake Michigan, except
in the oak belt. They make cylindrical conical pits in the sand (177,
179). The most characteristic species under the bark of fallen oaks is
the flatbug (Fig. 209).

b) The field stratum. — This stratum is dominated by many flowering
plants, such as Monarda, etc. The addition of a host of insects and
spiders not present in the earlier conditions is noticeable. Of the grass-
hoppers we add six species (Scudderia texensis, Xiphidium strictum,

Chloealtis conspersa,
Schistocerca rubiginosa,
Oecanthus Jasciatus, and
Conocephalus ensiger)

(40).

The andrenid bees
(Agapostemon splendens)
and various robber-flies
are numerous. On the
Monarda the honey-bees,
bee-flies (Fig. 210), bum-
blebees, and spiders {Mis-
times sus asperatus [Figs.
207, 208], Dictynafoliacea,
Agriope trifasciata, and
Epeira sp.) are common.
The blueberry is com-
monly one of the small herbs of the field stratum and upon it we find
several characteristic galls.

c) Shrub stratum. — This stratum is made up of the choke-cherry,
young oaks, rose, etc. The shrub which has been given most attention
is the choke-cherry. On this the lacebugs (Fig. 2 1 1) are often numerous;
the puss caterpillar (Cerura sp.) (163) sometimes occurs. This cater-
pillar has a pair of long projections at the posterior end. When disturbed
it extends and waves these projections and thus makes of itself one of
the most fantastic of our caterpillars.

Grapevines are not uncommon on the dunes and we often find a
curious red petiole gall on them, which is not common elsewhere. The
large fleshy larvae of the achemon sphinx (163) are sometimes taken.

Fig. 210. — A bee-fly (Bombylius major Linn.)
(from Williston after Lugger).

RED-OAK ASSOCIATION

233

d) Tree stratum. — The black oak (137) is attacked by a large, light-
green larva which has a narrow yellow stripe down its back (Nadata
gibbosa). It is also attacked by several slug caterpillars which we have
been unable to identify. The beautiful prominent larva with a saddle
of red is occasionally taken. Commonly feeding on the juices of
the leaves are several species of leaf-hopper (Typhlocyba querci var.
bifasciata), the common grapevine leaf-hopper, and the white black-
marked leaf-hopper which occurs also on the hickory. The oak tree-
hopper (Telemona querci) (Fig. 212) is a common leaf-sucker. Squirrels
are probably occasional visitors as they come to feed upon acorns. The
acorns are also often attacked
by weevils.

In such a set of graded
forest stages as we are dis-
cussing it is possible to note
many stages. The stage
which we have just de-
scribed passes more or less
rapidly into the next, the
rate of change depending
upon the height above
ground water and the degree
to which the sand is shifted
by the wind. On the parallel
ridges, the next and perhaps

most notable forest stage contains white oak and red oak and is found
in places on the Tolleston, Calumet, and Glenwood beaches. The
ecological age of the forest is determined by the height above ground
water. Ridge 93, inside the Tolleston Beach, is low and forest has
progressed as far as on the older beaches.

Fig. 2ii. — The lacebugs common on the oak
and wild cherry in the dune region (Corythuca
arena ta) (from Washburn after Comstock):
a, adult; b, young.

V. Mesophytic Forest Formation (115, 170)

I. HYALIODES OR BLACK OAK-RED OAK ASSOCIATION

(Station 63, also near stations 27 and 65; Tables L, LIII, LVI, LIX) (115)

This is represented at several points.

a) Subterranean-ground stratum. — In this stratum the woodchuck
or groundhog is common (142). Earthworms have begun to appear.
The root-borer Prionus (155) and several species of ants are common,
while the numerous digger-wasps of the earlier stage have largely dis-
appeared. The depressions which contain water in spring are typical

234

DRY AND MESOPHYTIC FOREST COMMUNITIES

forest temporary ponds. Beneath the leaves and wood are snails
(Zonitoides arboreus), millipedes {Polydesmus sp.), and centipedes (Litho-
bius sp.), and in dry weather Polygyra thyroides and multilineata.
Ground beetles and rove-beetles are common. One finds Cicindela

Fig. 212. — The oak tree-hopper {Telamona querci) (after Lugger).

sexguttata, the green tiger-beetle, here rarely; it is much commoner in

later stages, however.

In the decaying logs and stumps are darkling beetles (156), numerous

wireworms (Elateridae), and myriopods. Sometimes fungus-feeding

beetles (Diaperis hydni and Eustrophus tormentosus) are present in

numbers. Ants are also often
abundant. Carpenter ants are
common. The aphid housing
ant (Lasius umbratus subsp.
mixtus var. aphidicola) is some-
times abundant. In autumn
certain galleries in the wood
are crowded with woolly aphids
which are the so-called "cows"

Fig. 213. — The oak plant-bug (Hyallodes
vitripennis) (from Washburn after Riley) :
a, young; b, adult.

which the ants house for the
winter.

b) Field and shrub strata. —
In moist weather the snails (Polygyra) mentioned above are common
on the herbaceous vegetation, while the tree-frogs (Hyla versicolor and
pickeringii) (139) are common, and spiders are numerous.

c) Tree stratum. — The oaks (137) are affected by many of the same
species as in the earlier stages. The tree-frog is sometimes found in the

HICKORY ASSOCIATION

235

trees and the walking-stick (Diapheromera jemorata) (40) is common.
One of the most characteristic galls is the oak-seed gall (Andricus semi-
nator), particularly abundant on white oak of this stage and not common
later. Galls are very common on the white oak. The predatory capsid
(Hyaliodes vitripennis) (Fig. 213) is usually present on the bark of the
oaks, and is often in company with book-lice (Psocus). The squirrels,
chipmunks, and birds of this association are similar to those of the next
stage and will be discussed there.

Fig. 214. — General view of the white-oak red-oak hickory forest (Glencoe).

2. THE GREEN TIGER-BEETLE OR WHITE OAK-RED OAK-HICKORY
ASSOCIATION

(Stations 56, 64, 65; Tables LIV, LXI) (Fig. 214)

This is the climax forest of the savanna region. The groves are
largely made up of it. Though somewhat disturbed in localities where
studied, it presents some variations. Areas along the north shore contain
considerable basswood. The Higginbotham woods at Gaugars (Fig.
215) contain very few hickories and many maples; this type stands in
closer relation to flood-plain and marsh forests than those discussed
later. The woods at Suman are well invaded by beech and maple
seedlings and represent the latest stages of this forest. It is thought

236

DRY AND MESOPHYTIC FOREST COMMUNITIES

best to treat all phases together, simply mentioning the points of
difference.

a) Subterranean- ground stratum. — Earthworms, borers in the roots of
trees, and cicada nymphs are numerous. The wolf, groundhog, and
the red fox (Vulpes fulvus Des.) nest in burrows. The latter brings
forth from four to nine pups in early spring.

Consocies of the under side of leaves and wood: The camel cricket

A Mesophytic Forest

Fig. 215. — General view of the Higginbotham woods near New Lenox. Woods
of the flood-plain oak-hickory type.

(Ceuthophilus) (Fig. 216), young cockroaches, the short- winged grouse
locust (Tettigidea pennata Morse), and the yellow-margined millipede
(Fontaria corrugate) (Fig. 218) are most characteristic under the leaves.
The large round millipede (Spirobolus marginatus) (Fig. 217) is common.
Snails and slugs are numerous, several species {Polygyra pennsylvanica
[Fig. 219], P. profunda [Fig. 220], Zonitoides arboreus, Pyramidula alter-
nata [Fig. 221], Pyramidula solitaria [Fig. 222], Agriolimax campestris

HICKORY ASSOCIATION

237

Circinaria concava [Fig. 223]) are usually common and Polygyra albolabris
is characteristic of the more mesophytic parts.

The ruffed grouse, oven-bird, and woodcock nest on the ground.
The timber rattlesnake (Crotalus durissus Harlan) formerly occurred
in rocky situations (22). The four-toed salamander (Hemidadylium
scutatum Schl.) is found locally (22). The white-footed wood-mouse
(Peromyscus leucopus noveboracensis Fisch.) builds a nest under fallen

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219 220

22

222

223

Inhabitants of a Mesophytic Forest

Fig. 216. — The wingless wood locustid (Ceuthophilus) ; enlarged.

Fig. 217. — The common millipede (Spirobolus marginatus); natural size.

Fig. 218. — Another millipede (Fontaria corrugate) ; natural size.

Figs. 219-223. — Snails from the woods. 219, Polygyra pennsylvanica Green;
220, Polygyra profunda Say; 221, Pyramidula solitaria; 222, Pyramidula alternata;
223, Circinaria concava.

logs and stumps (21). The gray fox (Urocyon cinereoargenteus Mull.) is
more dependent upon heavy timber than the red fox (21). The cotton-
tail (21), which belongs to forest edge, frequently winters in the woods.
The bear was formerly common, nesting under fallen trees and feed-

2 3 8

DRY AND MESOPHYTIC FOREST COMMUNITIES

ing extensively on the berries. The timber wolf had its den in similar
places, though often burrowing into the ground. In Central Illinois
moles are common residents of groves near cultivated lands. The
Virginia deer (Odocoileus virginianus Bodd.) was formerly common and
was preyed upon by the wolves and panthers. The latter sometimes
leaped upon its prey from the branches of the trees (142).

Inhabitants of Trees and Shrubs

Fig. 224. — The spiny spider (Acrosoma gracilis), legs wanting (after Emerton).

Fig. 225. — Another spiny spider (Acrosoma spinea) : a, female; b, male; c, young
(after Emerton.)

Fig. 226. — Acorn weevils: a, dorsal view; b, side view (after Riley, U.S. D. Agr.).

Fig. 227. — A red-oak sawfly larva.

Fig. 228. — A female walking-stick on the trunk of a tree, with a caterpillar
(Halisidota sp.) on the bark above.

Consocies of logs (in wood and under bark) : There is a regular suc-
cession of forms which affect any one species of the trees of the forest.
The earlier forms usually attack the trees while they are standing, and
accordingly belong more properly to the tree stratum. When the bark

HICKORY ASSOCIATION

239

has become loosened, however, we find practically all the small inverte-
brates recorded on the ground. The small andrenid bees (Augochlora
pura) build small cells under the bank and fill them with pollen. One
egg is laid in each cell (July), and the larva feeds upon the pollen.
Sowbugs {Cylisticus convexus and Porcellio rathkei) and centipedes
(Lithobius, Lysiopetalum lactariutn, and Geophilus rubens) are common.
Numerous beetles burrow into the wood or feed on fungi under bark.
Some of the chief borers are (Cerambycidae) Prionus and Orthosoma
brunneum, and also Passalus comutus. The large slug (Philomycus
carolinonsis) is common.

Fig. 229. — The oak twig primer (Elaphidion villosum Fabr.) (after Washburn)
{17th Rept. Minn. Agr. Exp. Sta. y p. 165, Fig. 36).

b) Field stratum. — After rains the slugs and snails, especially the
young, crawl upon the vegetation. Several flies are common (Sapromyza
philadelphica). A leaf-hopper (Scaphoideus auronitens), a damsel-bug
(Reduviolus annulatus), the shield grasshopper (Atlanticus pachymerus) ,
and a spider {Theridium frondeum) have all been recorded.

c) Shrub stratum. — Many spiders build their nests and webs in this
stratum. Epeira domicilorum was found with a nest of leaves drawn
together adjoining its web. Epeira gigas, the large yellow spider, builds
near open places, on high shrubs. The web is a large orb, the nest in a
convenient group of leaves near the upper side.

240

DRY AND MES0PI1YTIC FOREST COMMUNITIES

Acrosoma gracilis (Fig. 224) (138, 172) commonly stretches its web
between the trunks of two small trees which stand about 4 ft. apart.
The center of the orb is commonly about 6 ft. above the ground; it is
nearly vertical. The spider usually hangs near the center.

The Standing Dead Oak and Inhabitants

Fig. 230. — Showing the larva, pupa, and adult of the large wood-eating beetle
(Passalus cornutus) ', about natural size.

Acrosoma spinea (Fig. 225a, b, c) (138, 172) commonly places its web
in a nearly horizontal position on the upper side of leaves. The spider
clings, ventral side up, on the lower side of the web. The web is
usually from 1 to 3 ft. from the ground. The spider often falls to the
ground when disturbed. The two Acrosomae are confined to mesophytic
forests of the oak-hickory type. They have not been recorded north of
Chicago.

HICKORY ASSOCIATION

241

A wasp (Polistes) builds its comb of wood pulp on the under side of
the leaves. Various larvae and beetles feed upon the leaves of the
undergrowth. A bug {Acanthocephala terminal is), a leaf-beetle (Calli-
grapha scalaris), the fork-tailed katydid (Scudderia furcata), the round-
winged katydid (Amblycorypha uhleri Brun.) (40), and various other
insects have been secured from shrubs, especially in slight open-
ings. The black snake (22) (now rare) often rests on bushes in such
forests. The black and yellow warblers and woodthrush nest on the
shrubs.

The Standing Dead Oak and Inhabitants

Fig. 231. — The successor of Passalus {Philomycus carolinensis) .
Fig. 232. — The work of a carpenter ant in the same tree.

d) Tree stratum. — The walking-stick (Fig. 228) (Diapheromera femo-
rata) (40) is common on the tree trunks in the fall. The red oak
supports the tree cricket (Oecanthus angustipennis) , the stinkbug
(Euschistus tristigmus), and the oak-leaf beetle {Xanthoma 10-notata).
Felt records several insects injurious to the red oak alone. From the
white oak we have taken the katydid (Cyrtophillus perspicillatus), the
larvae of sawflies (Fig. 227) and moths (Anisota senatoria), and various
galls. Several weevils (Fig. 226a, b) occur on acorns, and the twig-

242

DRY AND MESOPHYTIC FOREST COMMUNITIES

borer (Elaphidion villosum) (Fig. 229) in the twigs. The hickory
supports many larvae, including a Phylloxera which forms galls on the
leaves (see Fig. 277, p. 273).

The red-tailed and red-shouldered hawks, the red-headed wood-
pecker, the wood-pewee, the crow, bluejay, robin, and bluebird nest in
the trees. The panther and wildcat (Lynx rufus) were former residents.

Fig. 233. — The beech woods. Note small amount of undergrowth.

Dead standing oaks are attacked by a series of animals. As soon
as the wood begins to soften, the four-legged larva of Passalus cornutus
often appears. This is succeeded by slugs and ants (Figs. 230, 231, 232).

2. WOOD-FROG OR BEECH AND MAPLE FOREST ASSOCIATION

(Stations 70, 71, 71a, 71 b; Tables LV, LXII) (Fig. 233)
The coming of this stage is indicated by the presence of seedlings
of beech and maple in the oak-hickory forest, e.g., at Suman, Ind.

BEECH ASSOCIATION 243

a) Subterranean-ground stratum. — Earthworms continue; an occa-
sional groundhog has been seen, though they are probably much less
common here than in the preceding stages. The stratum appears less
closely inhabited than the preceding. Under leaves are found scattered
snails, centipedes, etc. The yellow-margined millipede (Fontaria cor-
rugate) is most common. There is an occasional Centhophilus. We
have found no other Orthoptera in beech woods proper, though
Hancock records several (40, p. 422). Animals are more abundant
under logs than under leaves. Here we find the large slug (Philomycus
carolinensis) and several species of snails which, though characteristic,

9 > ^

234 235 236
238 239

1
237

-

240

Figs. 234-240. — Some beech woods snails: Ground stratum; 234, Pyramidula
perspectiva; 235, Polygyra inflecta; 236, Polygyra palliata; 237, Polygyra frandulenta;
238, Polygyra oppressa; 239, Pyramidula solitaria, adult; 240, Polygyra albolabris.

are not abundant. These snails are Polygyra inflecta (Fig. 235),
oppressa (Fig. 2$$),fraudulenta (Fig. 237), palliata (Fig. 236), albolabris
(Fig. 240), Pyramidula solitaria (Fig. 239), alternaia, and perspectiva
(Fig. 234), and Zonitoides arboreus. These species of Polygyra are
distinguishable by the presence of characteristic "teeth" in the
entrance of the shells. The large spider (Dolomedes tenebrosus) and
millipede (Spirobolus marginatus) occur. Crane-fly larvae, ground
beetles (Plerostichus cdoxus), a centipede (Geophilus rubens) i the wood-
frog (Rana sylvatica) (Fig. 241) (139), and the red-backed salamander
(Plethodon cinereus) (152) (Fig. 242) are common and characteristic.

244

DRY AND MESOPHYTIC FOREST COMMUNITIES

Pickering's tree-frog is sometimes abundant. The oven-bird nests on
the ground.

b) Field and shrub strata. — The field stratum is very poorly devel-
oped in summer, herbaceous plants being most abundant in early spring.
The pawpaw supports the zebra swallowtail butterfly (Papilio ajax
Linn.), and the spice-bush the green-clouded swallowtail (Papilio troilus
Linn.). In the shrubbery in general we have taken snout-beetles, leaf-
beetles, etc., usually as incidental occurrences, however. A lacebug
(Gargaphia tiliae), which has been recorded on bass wood, and several

Representatives of the Wood-Frog Association
Fig. 241. — The wood- frog (Rana sylvatica); about natural size.
Fig. 242. — The red-backed salamander (Plethodon cinereus); about natural size.
Fig. 243. — The remains of a fungus found growing under a pile of logs in moist

woods (not beech), and the fungus-feeding beetle (Tritoma unicolor Say); about

natural size.

species of bugs and beetles have also been taken, but all are incidental
and of widely distributed species.

c) Tree stratum. — On trunks, shelf fungi are common and are usually
inhabited on the under side by the tenebrionid beetle (Boletotherus
bifurcus) (156), a curious rustic beetle. Few characteristic species have
been taken from the trees. From the bark of the trunk we have taken
harvestmen (Oligolophus pictus and Liobunum nigropalpi) and from the
twigs woolly aphids (Pemphigus imbricator) (Fig. 245). There is an
occasional Io larva on the leaves (Fig. 244).

The great crested flycatcher, wood-pewee, bluejay, scarlet tanager,
red-eyed vireo, and woodthrush nest in the low trees and on the lower

BEECH ASSOCIATION

245

levels of the higher trees. Little is known of the mammals of the beecn
and maple forest. Deer, bears, wolves, foxes, hares, etc., appear to
prefer forests with more undergrowth and herbaceous vegetation.
Squirrels are fond of beechnuts, and are probably the chief resident
mammals. The fox squirrel, gray squirrel, red squirrel, and other mam-
mals of the preceding stages doubtless occur.

d) Consocies of the decay of a beech. — Succession: Any tree which
is torn down by the wind or lightning is attacked by a series of borers,

Leaf- and Twig-Feeders

Fig. 244. — The nest of an Io caterpillar in the beech leaves; reduced.
Fig. 245. — Woolly aphids {Pemphigus imbricator Fitch) on the twig of the beech;
reduced.

etc., each one helping to prepare the way for those that follow. To
illustrate the general principles, the succession of animals in any species
of tree might be presented. We have chosen the beech.

According to Felt (137), living beeches are commonly attacked by the
red-horned borer {Ptilinus ruficornis Say) which bores into the bark
and wood, and another borer (Anthophilax attenuatus Hald.) which lays
eggs in the galleries thus formed. We have examined four stages of the
decay of beech trees.

246

DRY AND MESOPHYTIC FOREST COMMUNITIES

First stage: Tree freshly fallen (Fig. 246). Only forms recorded are
the apple-tree engraver beetle (Pterocyclon mali Fitch) (Fig. 247) which
makes galleries in the solid wood.

Succession in the Beech Log

Fig. 246. — The freshly fallen beech.

Fig. 247. — The first borer to enter the fallen tree {Pterocyclon mali Fitch);
greatly enlarged (from Lugger after U.S. Dept. Agr.).

Fig. 248. — The partially decayed beech.

Fig. 249. — Closer view of the same showing the burrows of the different wood-
boring larvae in the softened wood.

Fig. 250. — Shows the last stage in the decay of the beech.

CAUSES OF SUCCESSION 247

Second stage (Fig. 248): Bark loosened; wood still solid or barely
softened. Under the bark were the flattened Pyrochroidae larvae, the
small snail {Zonitoides arbor eus), a few of the four-legged larvae of
the passalid (Passalus comutus), many larvae of fungus-gnats (Myceto-
philidae), and a single specimen each of the beetle (Penthe pimelia) and
the slug (Philomycus carolinensis). None of these were abundant.
The flattened beetle larvae were most characteristic.

Third stage (Fig. 249): The wood is thoroughly softened and the
bark generally loosened. Here the animals present in the earlier stage
are increased in numbers. The passalid larva is more abundant.
Slugs are numerous. Snails {Pyramidula alternata) are found in such
situations as are large enough for them to enter. Fungus-eating beetles
are present (Megalodacne heros Say). A click-beetle larva {Thar ops
ruficornis Say) bores into the softened wood.

Fourth stage (Fig. 250): The bark fallen off; the log a mere mass of
rotten wood. Such a log is only shelter for the regular inhabitants of
the forest floor which we have already enumerated on the preceding
pages.

VI. General Discussion

A study of the tables shows several points of interest. Take first
the ground stratum. Beetles which live under decaying wood are
common on the beach where the decaying wood is common, but are
absent through the Cottonwood, pine, and black-oak stages. They
appear again with the fallen leaves and moist logs of the black oak-red
oak stage. Vegetation in itself is not directly important. Moist
decaying wood is common, both on the beach and in the woods. Wood
and moisture are evidently essential to such animals. Turning to the
snails, which probably all come out into the open to feed during the night
and during moist weather, we note that they do not appear until the
under-log beetles put in their second appearance. In general the total
number of species and of individuals increases until the oak-hickory
stage is reached and falls off again in the beech and maple stage.

In general we note that as the forest passes from the bare-sand stage
to the beech-maple stage, there is a great increase in the space to be
inhabited by animals and the diversity of possible habitats, at least up
to the oak-hickory stage.

I. CAUSES OF SUCCESSION

The causes of succession in forests are chiefly changes in physical
condition with increase in denseness of vegetation, such as the increase

248

DRY AND MESOPHYTIC FOREST COMMUNITIES

of moisture of the atmosphere, decreased light, decreased temperature
maximum in summer. The poisoning of the soil by root excretions
and the modification of conditions on the ground brought about by a

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four of the animal communities (after Fuller).

given set of trees are believed to prevent the germination of seeds of
most of such trees, and at the same time to prepare the way for those of

CAUSES OF SUCCESSION

249-

differently adapted species. The factors as expressed in terms of the
evaporating power of the air are shown in Figs. 251,252, and 253, which
are graphic representations of the results of a season's study by Fuller
(131). The graph of the cottonwood dunes is characterized by great
fluctuations.

The graph for the pine dunes is decidedly lower and more regular in its
contour than that of the association which it succeeds. Its four nearly equal

10 20

Cottonwood dune

Pine dune
Oak dune

Oak-hickory forest
Beech-maple forest

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Fig. 252. — Showing the comparative evaporation rates (c.c. per day) in the ground
stratum of the different animal communities from May to October (after Fuller).

10 20 30

Cottonwcod dune
Pine dune
Oak dune
Beech-maple forest

Fig. 253. — Showing the comparative evaporation rates (c.c. per day) in four of the
animal communities on the basis of the maximum amount per day for any week from
May to October (after Fuller).

maxima would indicate that within its limits there was, throughout the sum-
mer season, a continuous stress rather than a series of violent extremes. On
the whole it shows a water demand of little more than half of that occurring
in the cottonwood dunes. Its greatest divergence is plainly due to the ever-
green character of its vegetation and is seen on its low range in May and the
first part of June, and again in October when it falls below that of the oak
dunes and is even less than that of the beech-maple forest. This would give
good reasons for expecting to find within this association truly mesophytic
plants [and moist forest annuals] 1 whose activities are limited to the early
1 The words in brackets are added.

250 DRY AND MESOPHYTIC FOREST COMMUNITIES

spring. Evaporation in the various associations varies directly with the order
of their occurrence in the succession. The differences in the rate of evapora-
tion in the various plant associations studied are sufficient to indicate that
the atmospheric conditions are most efficient factors in causing succession
(Fuller, 131).

A comparison of Fuller's (131) data with the tables or lists of ani-
mals shows that the distribution and succession of animals is clearly
correlated with the evaporating power of the air. Further comparison
with the description of different forest stages shows that the evaporating
power of the air may be taken, in this case, as an index of the materials
for abode, etc.

2. CHARACTERS OF THE COMMUNITIES

It is possible to characterize the formations of the forest in physio-
logical terms, though these cannot be of a very definite kind until the
mores have been studied in detail, and accurate measurements made.
Taking them stratum by stratum, we may note the following obvious
characters:

a) Pioneer communities. — The communities of the cottonwood, pine,
and black-oak stages may be designated as pioneer because of the
presence of bare mineral soil.

Subterranean and ground strata: (a) The cottonwood community
is characterized by animals which breed and spend the dark and cloudy
days chiefly below the surface of the sand. They are very largely
diurnal and predatory, and are exceedingly swift and wary. The bur-
rowing spider (Geolycosa pikei) is one of the few nocturnal animals.

(b) The pine community is characterized by similar mores, but is
to be distinguished from the preceding by the presence of many animals
which prefer sand that is less shifting and which is slightly darkened by
humus (170). Animals requiring "cover," such as the lizard, the blue
racer, a few ground squirrels, etc., give character because of their absence
from earlier and later communities.

(c) The black-oak community represents the climax of diversity
of the subterranean and ground strata. The bare-sand mores continue
in the open spaces, which we have designated as transition areas. Leaf-
cutters are now present, while among the burrowers the root-borers
(prionids and lucanids) work on the roots of the decaying trees. The
behavior differences between this and the preceding community are
differences of detail which, for the making of deductions, would require
much careful study.

CHARACTERS OF COMMUNITIES 251

Field and shrub strata : The field and shrub strata of the Cottonwood,
pine, and oak communities are less easily characterized. The cotton-
woods of the beach are far less commonly infested with aphid galls than
are trees of the same species growing in less exposed situations. Further-
more we have never found any of the lepidopterous larvae such as
Basilarchia archippus Cram, near the beach. Animals living exposed
upon the trees are few in number. The same general conditions obtain
on and among the pines but spiders are more numerous. On the black
oak the number of phytophagous animals is increased and the number of
galls appears to be greater than in the later stages; the inhabitants of
the herbaceous vegetation are chiefly those found in open situations such
as prairies and roadsides, where the physical conditions are similar.
Some animals of the same species which make up the black-oak com-
munity were taken from a roadside, and after being mixed with the
inhabitants of the shrubs of the beech forest were placed in a light gra-
dient. Soon the insects and spiders of the two communities separated
sharply from each other, the beech-inhabiting species going to the dark-
est end while the roadside species crowded to the light.

b) Later communities. — With the coming-in of red oak, true forest
with the mineral soil largely covered with humus and leaves is present
and very different mores obtain. The diurnal diggers are practically
absent. Snails, beetles, grasshoppers, spiders, and myriopods living
under bark, decaying wood, and leaves, avoiding strong light and
requiring moisture, are the chief types. The mores are typically forest
in character. The differences between these and the later stages are
those of detail and degree. In general with a lessening in the severity
of the conditions and an increase in the denseness of vegetation, there is
a proportional increase in the use of the vegetation as a place of abode.

In the field and shrub strata, we note that the animals of the cotton-
wood, pine, and oak stages are characteristic of open dry situations,
requiring or tolerating strong light, while those animals of the red-oak,
hickory, and beech stages are negatively phototactic to light of the same
intensity, as shown by mixing the animals in a gradient.

The animals of the tree strata frequent a limited number of kind:,
of trees. Tree inhabitants are few and scattered in the Cottonwood,
pine, and black-oak stages while animals inclosed in galls or cases are
common, if not dominant. In the red-oak, hickory, and beech stage
phytophagous animals are often gregarious and numerous. Groups such
as Orthoptera, beetles, bees, and wasps are represented more and more
by species which make use of the vegetation as forest development
goes on.

252

DRY AND MESOPHYTIC FOREST COMMUNITIES

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ANIMALS OF FOREST SUCCESSION

253

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254

DRY AND MESOPHYTIC FOREST COMMUNITIES

TABLE XLIX. (Table L precedes Table XLLX)

Showing Forest Animals in the Early Stages of Forest Development of a
Clay Bluff of Lake Michigan
Subterranean and ground strata, i, bare clay, 2, sweet clover, 3, shrubs, golden-
rod, etc., 4, sapling stage, animals same as in (5) the oak-hickory forest (Station 56)

Common Name

Tube-weaver

Lycosid

Carolina locust

Mud-dauber

Tiger-beetle larvae

Sowbugs

Centipede

Snail

Snail

Snail

Tiger-beetle larvae

Snail

Slug

Yellow-margined millipede
Centipede

Scientific Name

Agelena naevia Wal

Pardosa lapidicina Em

Dissosteira Carolina Linn

Pelopoeus cementarius Dru

Cicindela purpurea limbalis Klg.

Porcellio rathkei Brandt

Geophilus sp

Polygyra thyroides Say

Pyramidula alternata Say

Polygyra monodon Rack

Cicindela sexguttata Fbr

Polygyra albolabris Say

Philomycus carolinensis Bosc. . .

Fontaria corrugate Wood

Lysiopetalum lactarium Say ....

1234

* *

* *

* *

* *

* *

F C A

* * *

* * *

* * *

* *

* *

* *

* *

* *

* *

ANIMALS OF FOREST SUCCESSION

255

ANIMALS RECORDED IN THE GROUND AND SUBTERRANEAN
STRATA OF THE STAGES NOTED

In Tables LI-LV, in the third column B indicates breeding; F, feeding; H,
hibernating, on the situation indicated in column 4. Figures in column "Litera-
ture" refer to literature cited in the special Bibliography at the end of the book.
Statements made on the authority of others are in italics; those starred are by
A. B. Wolcott.

TABLE LI

Pine Stage (Stations 57, 58, 59)

Common Name

Scientific Name

Literature

Bee (Andrenidae)

HaLcius nelumbonis Rob . . .

Tachytes texanus Cres

Plesia interrupta Say

Anoplius marginatus Say. . .
Coluber constrictor Lin., Var.
Citellus 13-lineatus Mitch . . .
Cardiophorus cardisce Say. . .
Alans my ops Fabr

B?

B
B

B?

181

Larridae

173

Scoliidae

Ceropalidae

In sand
a

it

On sand

Under pine

bark

173

157

21

156

Blue racer

Ground squirrel

Beetle (Elateridae).. . .
Elaterid beetle

TABLE LII

Black-Oak Stage (Stations 57, 59, 60, 61)

Common Name

Scientific Name

Literature

Elateridae

Erotylidae

Lacon rectangularis Say

Languria trifasciata Say ....
Hippiscns tuberculatus Beau.
Coelioxys rufitarsus Smith. . .

Odynerus anormis Say

Heterodon platirhinos Latr . .

B
B
B
B

B

Under Opuntia
u

In sand
Bee nest

*
*

Coral- winged locust. . .

Parasitic bee

Eumenidae

40

Hog-nosed snake

In sand

157

TABLE LIII
Black Oak-Red Oak Stage (Station 63)

Common Name

Scientific Name

Literature

Ant

Ant

Lasius umbratus mixtus
aphidicola Walsh .......

Camponotus ligniperdus
noveboracensis Fitch

Pterostichus sayi Brulle

Uloma impressa Mels

B

B
B
B

Log

Log
Rotten log
Rotten log

54

Ground beetles

Tenebrionidae

54
156
156

256

DRY AND MESOPHYTIC FOREST COMMUNITIES

(See explanation above Table LI)

TABLE LIV

Red Oak-Hickory Stage (Stations 64, 65, 69)

Common Name

Scientific Name

Literature

Green tiger-beetle ....
White-faced hornet . . .
Andrenidae

Cicindela sex guttata Fabr . . .

Vespa maculata Lin

Augochlora pur a Say

Geotrupes splcndidus Fabr. . .
Staphylinus violaceus Grav . .
Melanotus communis Gyl . . .

Pall if era dorsalis Bin

Eupsalis minuta Dru

B
H

In soil
Rotten wood

151
179

Scarabaeidae

Staphylinidae

Elateridae

Slug

Brenthid beetle

B
B

B
B

Rotten log
a

a

Log
Solid logs

156

156

156

91

TABLE LV

Beech Stage (Stations 70, 71, 71a, 71&)

Common Name

Frog

Fly larva

Salamander. . . .

Snail

Snail

Snail

Snail

Snail

Snail

Beetle

Ant

Scientific Name

Rana sylvatica Le Conte. . .
Pachyrhina ferruginea Fabr

Plethodon cinereus Gr

Polygyra inflecta Say

Polygyra oppressa Say ....
Polygyra fraudulenta Pil . . .

Polygyra palliata Say

Pyramidula solitaria Say . .
Pyramidula perspectiva Say
Xyhpinus saperdioides Oliv
Aphaenogaster tennesseensis
Mayr

F

B

BF
BF
BF
BF
BF
BF

?

B

B

Ground

Under leaves
u

Leaves and log

Under bark
Rotten wood

Literature
139

91

91

91

156, 137

ANIMALS OF FOREST SUCCESSION

257

TABLE LVI

Distribution of Animals Recorded from Vegetation in More Than One of
the Animal Communities of the Forest Stages Indicated by Numbers
1, the cottonwood stage; 1-2, mixed cottonwood and pine stage; 2, pine stage;
2-3, mixed pine and oak stage and open places in the oak forest; 3, black-oak stage,
in its later phases white oaks occur; 4, black oak-red oak stage; 5, stages containing
hickory but not beech and maple; 6, beech and maple stage.

Common Name

Scientific Name

1

1-2

2

2-3

3

4

s

6

(a) Spider (Thomisidae)

(b) Butterfly

Philodromus alaskensis Key
Anthocharis genutia Fabr. .
Epeira domicilorum Hentz. .

Lygus pratensis Lin

Diapheromera femorata Say
Misamessus asperatus Htz .
Dictyna foliacea Hentz . . .

Epeira gigas Leach

Theridium frondeum Hentz.
Acanthocephala terminalis

Dall

Nezara hilaris Say

Podisus maculiventris Say. .
Sapromyza philadelphica

Mac

*

*
*

*

*

*

*

?
*

*

?
*

?

*
*
*
*

*
*
*

F
F

*

*

*

*

C

*

*
*

*

(c) Spider (Epeiridae) . .

(d) Dusky plant-bug . . .

(e) Phasmidae

(/) Spider {Thomisidae)
(g) Spider (Dictynidae) .
(h) Spider (Epeiridae) . .
(i) Spider (Theridiidae)
(j) Bug

(k) Stinkbug

(/) Stinkbug

(m)F\y

*

*
*

F

*

*
*

*

The letters below at the left refer to the species opposite which they stand in
Table LVI and the numbers refer to the forest stages as at the heads of the columns
of Tables L and LVI. The capitals have the same meaning as in the preceding tables.

a — from cottonwoods and juniper (1, 1-2, 3) (138, 172).

b — from Arabis lyrata (175).

c — from pine and herbaceous vegetation (B) (4) (172).

d — herbs (174).

e — from the trunks of various trees.

/ — Monarda (2-3), and black oak (3), maple (5) (138, 172).

g — F Monarda (3) (173).

h — from undergrowth (4), and beech (5) (138, 172).

* — from shrubs (4), and young beech (5) (138, 172).

j — shrubs (4) and maple trunk.

k — from red-oak trunk (4) and beech trunk (5) (Tilia, Citrus, Gossypium 186).

/ — ? (4) and beech leaves (5) (predaceous, 185).

m — herbs.

258

DRY AND MESOPHYTIC FOREST COMMUNITIES

ANIMALS RECORDED FROM THE FIELD, SHRUB, AND TREE
STRATA OF THE FOREST STAGES NOTED

In Tables LVII-LXII, in the third column B indicates breeding; F, feeding;
H, hibernating, on the situation indicated in column 4.

TABLE LVII

Cottonwood Stage (Stations 57, 58, 59)

Common Name

Scientific Name

Literature

Chrysomelid beetle . .
Long-horned borer. . .
Gall aphid

Disonycha quinquevittata Say .

Plectrodera scalator Fab

Pemphigus populicaulis Fitch.
Pemphigus vagabundus Walsh.

BF
BF
BF
BF

Willow
Cottonwood

«
u

156
156
188

Gall aphid

188

TABLE LVIII
Pine Stage (Stations 57, 58, 59)

Common Name

Scientific Name

Literature

Leaf-beetle

Nodonota tristis Oliv

Bassareus lativittis Germ ....
Xysticus formosus Banks. . . .
Dendryphantes octavus Hentz .

Theridium spirale Em

Ips grandicollis Eich

Evetria comstockiana Fern. ?. .

F
F

BF
BF

Herbs
a

Juniper
a

a

Pine
a

156,137

Spider (Thomisidae)..
Spider (Attidae)

Spider {Theridiidae) . .

Engraver beetle

Pitch-moth

137
187, 138

173
138, 172

*37
137

ANIMALS OF FOREST SUCCESSION

259

(See explanation above Table LVII)

TABLE LLX

Black-Oak Stage (Stations 57, 59, 60, 61)

Common Name

Scientific Name

Milesia virginiensis Dm

Agapostemon splendens Lepel.
Philodromus per nix Black. . . .

Argiope trifasciata Forsk

Chloealtis conspersa Har

Schistocerca rubiginosa Har . .
Oecanthus fasciatus Fitch. . . .
Scudderia texensis Scud

Conocephalus ensiger Har. . . .
Xiphidium stridum Scud ....
Euschistus variolar ius Pal. . . .

Triphleps insidiosus Say

Cerura sp

Otiocerus degeeri Kirby

Neuroctenus simplex Uhl

Ditoma quadriguttata Say ....
Heterocampa guttivitta Harr. . .

Nadata gibbosa S. and A

Telemona querci Fitch (monti-

cola)

Chariesterus antennator Fabr. .
Typhlocyba querci var. bifas-

ciata G. and B

Phlepsius irroratus Say

Literature

F

Herbs

F

Primrose

177

F

Herbs

137

F

a

137

F

a

40

F

u

40

BF

a

40

BF

a

40

BF

«

40

BF

u

40

BF

ft

174

F

ft

185

BF

Cherry

186

BF

Oak

185

BF

a

185

F

«

137

BF

ft

x 37

BF

«

138

BF

ft

185

BF

185

BF

«

185

BF

<(

185

Syrphus fly

Andrenid

Spider {Thomisidae)..
Spider (Epeiridae) . . .
Sprinkled locust.

Grasshopper

Tree-cricket

Texas grasshopper . . .
Conehead grasshop-
per

Meadow grasshopper

Stinkbug

Flower-bug

Fork-tailed larvae . . .

Fulgorid

Flatbug

Colydiid beetle

Prominent larva

Prominent larva

Tree-hopper

Coreidae

Jassid

Jassid

260

DRY AND MESOPHYTIC FOREST COMMNITIES

(See explanation above Table LVII)

TABLE LX

Black Oak-Red Oak Stage (Station 63)

Common Name

Scientific Name

Literature

Jumping spider

F
B

F
F

Herbs
a

White oak

Tree trunks

Cherry

133

Gayenna ccler Htz

White-oak gall

Predaceous leaf-bug. .
Scallop-moth (larvae)

Andricus seminator Harr

Hyaliodes vitripennis Say ....
Hydria undulata Lin

188

TABLE LXI

Red Oak-Hickory Stage (Stations 64, 65, 59)

Common Name

Scientific Name

Literature

Rove-beetle

Spider (Clubionidae) .

Locustidae

Spider (Epeiridae) . . .
Spider (Epeiridae) . . .
Spider (Epeiridae) . . .
Jassid

Tachinus pallipes Grav

Anyphaena cons per sa Key. . .
Atlanticus pachymerus Burm.

Acrosoma gracilis Wal

A crosoma spinea Hentz

M angora maculata Key

Scaphoideus anronitens Prov .

Odontota nervosa Panz

- Reduviolus annulatus Reut. . .
Linyphia phrygiana Koch. . . .

Cicada linnet S. and G

Calligrapha scalaris Lee

Euschistus tristigmus Say ....
Halisidota sp

BF
F
B
F
F

B

F

BF
BF
BF
BF
BF

B

F

B

B

B

Mushrooms
Herbs
Grass
Shrubs

ft
«
ft

Young maple
«

ft

White oak

<(

Red oak

ft

ft

Maple

Hickory

ft

177
138
40
138
138
138
177

Beetle

Bug (Nabidae)

Spider (Liny pkiidac) .
Cicada

138

177

Leaf-beetle

Stinkbug

J 37

Oakworm

Anisota senatoria Sm. and Abb.
Oecanthus anguslipennis Fitch.
Cyrtophyllus perspicillatus L. .

Xanthoma 10-notata Say

Symmerista albifrons S. and A.
Datana angusii G. and R . . . .
Phylloxera caryae-caulis Fitch.

T 37

Tree-cricket

Katydid

40

Leaf-beetle

Prominent larva

Prominent larva

Aphid

137

137

188,137

ANIMALS OF FOREST SUCCESSION

261

(See explanation above Table LVII)

TABLE LXII
Beech Stage (Stations 70, 71, 71a, yib)

Common Name

Scientific Name

Literature

Beetle

Fungus-beetle. . .
Cercopidae (bug)

Leaf- hopper ,

Leaf-hopper. . . .
Ichneumonidae. .

Lacewing

Lacebug

Ichneumonidae. .
Pentatomidae . . .
Lampyrid beetle.

A ttidae

Theridiidae

Harvestman. . . .
Syrphus fly

Boletobius ductus Grav. . . ,
Boletotherus bifurcus Fabr.
Clastoptera obtusa Say

Gypona octolineata Say ,

Jassus olitarius Say

Thalessa at rata Fabr

Chrysopa rufialbris Burm. .
Gar ga phi a tiliae Walsh ....

Trogus vulpinus Cb

Banasa calva Say

Podabrus basilaris Say. . . .

Wala mitrata Hentz

Xotionella inter pres Cam. . .
Oligolophus pictus Wood. . .
Spilomyia longicornis Loew.

Mushrooms

Shelf fungus

Hickory, maple

hazel
Hickory, maple
beech
Maple
Larvae
Maple
Beech
Larvae
Beech
Maple

Maple trunk

177
77,i37

185-
137

*37
137

137
177

137
138
138
184

CHAPTER XIII

ANIMAL COMMUNITIES OF THICKETS AND FOREST MARGINS

I. Introduction

The forest margin or forest edge is a familiar natural situation.
About Chicago there are groves of trees which are probably exactly as
they were before settlement. The forest ends; the prairie begins. The
line between the two is markedly a narrow border of shrubs and rank
weeds, usually only a few feet wide. In other places the forest ends at
a marsh side, lake side, or stream side, but almost always with the
thicket of shrubs and rank weeds. A remarkably large number of
animals belong to this forest margin. Some of these have been discussed
in connection with the margins of bodies of water (chap, x), and the
marsh forest (chap. x). The borders between forest and prairie
remain to be discussed. These will be roughly separated into high and
low forest margin, depending upon height above ground-water level.
The relations of these formations to the other forest margins will be
indicated in the tables.

II. Low Forest Margin Sub-Formations

(Stations 45, 49; Table LXIII) (Fig. 254)

Low forest margin is usually the border between swamp forest and

low prairie. There was originally much of this in the Lake Chicago

plain. One point of special study is the border of the Wolf Lake marsh

forest (see p. 189).

I. SUBTERRANEAN-GROUND STRATUM

The ground is inhabited by earthworms and cicada nymphs, etc.
No burrowing mammals have been recorded, but it is probable that
the skunk sometimes breeds in this stratum.

The cricket (Nemobius maculatus) occurs under fallen leaves, sticks,
etc., with an occasional snail (Polygyra monodon). The lubberly locust
often deposits its eggs in the ground (40). Sowbugs and forest-floor
forms make up most of the remaining species.

The northern yellowthroat, the song sparrow, and the common
shrew sometimes nest on the ground. The skunk is sometimes a feeding
resident.

262

MOIST FOREST MARGIN 263

2. FIELD AND SHRUB STRATA

Here two zones may be recognized. While there is no reason for
separating them in the ground stratum, a rough separation is here
possible.

a) Rank weeds, willow, dogwood, grape, etc.

b) Prickly ash thicket with grape and young elms.

Outside the first is a girdle of low prairie from which low prairie plants
and some low prairie animals occasionally invade the forest margin.

a) Girdle of rank weeds, dogwood, willow, etc. — In open, grassy places
the garden spiders (Argiope aurantia and trifasciata) (Fig. 255) fasten

Fig. 254. — Low forest margin at Wolf Lake, Ind. In front of a, low prairie
area; opposite b, belt of rank weeds: opposite c,Jow shrubs; opposite d , high shrubs;
opposite e, trees.

their webs to any firm support, such as a young shrub. Various grass-
hoppers occur in open situations (Xiphidium fasciatum and brevipenne
belong more properly to low prairie) (Fig. 256). The long-bodied spider
(Tetragnatha labor iosa) (138) is a common resident. On the grasses
beneath the shrubs the black-sided grasshopper {Xiphidium nigropleura)
is abundant. The snail (Fig. 257) (Succinea ovalis) is sometimes
common.

Of the bugs which frequent the blossoms of the coarse weeds are the
long-legged bug (Neides muticus), the buffalo tree-hopper (Fig. 259), and
the candlehead (Scolops sulcipes) (Fig. 258). These two and especially
the latter, with its curiously prolonged prothorax, are the most char-
acteristic. The common plant-bug (Lygus pratensis) (Fig. 261) and an

264

THICKET COMMUNITIES

occasional dusky leaf-bug (Adelphochoris rapidus) (Fig. 262) are also
found. The large stinkbugs (Euschistus tristigmus and fissilis Uhl.) are
common. They may be predatory in the adult stage. The predatory
ambush-bug (Phymata erosa fasciata) lies in wait for its prey in the

Fig. 255.
natural size.

-The garden spider (Argiope aurantia) on its web; about one-half

Fig. 256. — The slender meadow grasshopper {Xiphidiumfasciatum) (after Lugger) .

blossoms. A crab spider (Mesumena vatia) and a jumping spider
(Phidippus audax) are common in the blossoms (40, p. 182.) Various
lepidopterous larvae feed upon the rank weeds also.

Gn weeds and blossoms grasshoppers are numerous; we find the Ne-
braska conehead {Conocephalus nebrascensis) (see Fig. 260), the lubberly

MOIST FOREST MARGIN

265

y 1 f. , -7 fc v; . '-''-- r; ^' ' J - i ' ^"''' i ;V ' ' '"• ■ " ' '

257

Fig. 257. — The forest-margin snail (Succinea ovalis); twice natural size (after
Baker).

Fig. 258.— The candle-headed bug (Scolops sulcipes)\ 5 times natural size
(original) .

Fig. 259.— The buffalo tree-hopper (Ceresa biibalns); 5 times natural size (after
Marlatt, U.S. Dept. Agr.).

Fig. 260. — The large cone-headed grasshopper (Conocephalus robustus) (after
Beutenmuller [Am. Mus.] from Blatchley).

266

THICKET COMMUNITIES

locust {Melanoplus differ entialis) , an occasional red-legged locust, and the
striped shrub cricket, the short-winged brown locust (Stenobothrus cur-
tipennis), the short- winged meadow grasshopper (Xiphidium brevipenne),
and the Texas katydid (Scudderia texensis) (40, pp. 330, 390).

The jug-making wasp (Eumenes fratemus) (40, p. 207) makes its
jug-like nest on the herbaceous plants. The social wasp (Polistes) is
a frequent visitor of the flowers,
and sometimes attaches its comb
to the willow. The oblong leaf-
winged katydid (Amblycorypha
oblongifolia) (Fig. 263) (40, p.
391) and the fork-tailed katydid

261 262

Fig. 261. — The tarnished plant-bug (Lygus pratensis); about one- fourth of an
inch long (after Forbes) .

Fig. 262. — The dusky leaf-bug (Adelphocoris rapidus); about one-fourth of an
inch long (after Forbes).

{Scudderia furcata) (Fig. 264) are residents. The latter places its egg
on leaves of shrubs (40). Willow leaf-feeders are numerous; several
lepidopterous larvae are common. These include the brilliant larva of
the smeared dagger-moth (Fig. 265), the cecropia moth, the willow
sphinx, the viceroy and mourning-cloak butterflies, the maia moth
(Fig. 266), the fork-tailed caterpillar (137), larva of the maia moth,
and others. The small fly (Bibio albipennis) visits the flowers of the

MOIST FOREST MARGIN

267

willow in spring (Fig. 267). Sawfly larvae are common; the large light-
colored one (Cimbex americana) (179) has habits of special interest. The
female, which is a wasp-like insect, deposits her eggs on the under sides

of leaves. Blisters are formed, and a
young larva lives for a time in each

263

264

Fig. 263. — The oblong leaf-winged katydid (Amblycorypha oblongijolia); (after
Forbes) natural size.

Fig. 264. — The fork-tailed katydid (Scudderia furcata) (after Lugger from
Forbes) ; natural size.

of these. Later it is to be found living freely on the leaves. It usually

rests with the posterior segments wrapped around a petiole or twig.

Pupation takes place in a

silken case. The spotted

sawfly larva (Pteronus

ventralis Say) (179) is less

common.

Beetles are common
on the willow. The leaves
are eaten by May-beetles
(189) and several leaf-feed-
ers (Calligrapha and Lina
are common). Several
borers attack the twigs
(Saperda concolor). Galls
are very numerous. The
trunks of small willows are
commonly attacked by the
larvae of the introduced
snout-beetle (Cryptorhyn-
chus lapathi), and the
goat-moth larva {Prionoxystus robiniae Peck.), which bores in the heart-
wood. The sap which exudes attracts many sap-beetles (Nitidulidae) .

Fig. 265. — The adult and larva of the smeared
dagger-moth {Acronyda oblinita), which feeds upon
various forest-margin weeds and shrubs; natural
size (after Riley).

268

THICKET COMMUNITIES

The dogwood is fed upon by a few larvae. The unicorn larva
(Schizura sp.) is occasionally found; the young of the spittle insect
(Aphrophora 4-notata) are common. The grape and Virginia creeper are
attacked by several sphinx larvae. The grapevine hog caterpillar
{Ampelophagus myron Cram.) has been taken from the former.

Nesting in the shrubs are the goldfinch (more often in trees), the
indigo bunting, the northern yellowthroat, the brown thrasher, and

catbird, all of which feed in the
low prairie. The song sparrow
nests near the ground.

b) The belt of prickly ash. —
This has not been so thoroughly
studied. The subterranean and
ground strata are similar to
those of the forest adjoining (see

2C6

2C7

Fig. 266. — The larva of the maia moth (Hemileuca maid) which feeds on the
willow; natural size (from Lugger after Riley, Div. Ent., U.S. Dept. Agr.).

Fig. 267. — Bibio albipennis. Early spring on the flowers of the willow. Breeds
in the ground (from Williston after Washburn).

p. 269) ; the ground and field strata have some of the same residents.
The adult Cresphontes butterfly (Papilio cresphontes) is common about
the Wolf Lake forest edge and Hancock (40) has recorded the larva on
prickly ash, one of its regular food plants. He also records the true tree-
cricket (Apithes agitator Uhl.) as inhabiting prickly ash thickets.

III. High Forest Margin Sub-Formations

(Station 48; Table LXIV)

This surrounds the oak-hickory, black-oak, and beech forests on high

ground. The witchhazel, hawthorn, sumac, and grape are the dominant

shrubs; goldenrod, asters, and sunflowers are the chief herbaceous plants.

DRY FOREST MARGIN 269

I. SUBTERRANEAN-GROUND STRATUM

Certain earthworms, cicada nymphs, and root-eating grubs belong
here. This is the regular breeding-place of the skunk {Mephiti: meso-
tnelas avia Bang). According to Seton (143) they go in droves of six or
eight, and as many as fifteen sometimes occur in a winter den. Accord-
ing to Seton its food consists of various insects, grasshoppers, crickets,
meadow mice, snakes, and crayfishes. The short-tailed shrew in primeval
conditions breeds chiefly in such tangles of bushes. It digs in moss
and fallen leaves and loamy soil, and follows mouse galleries. According
to Wood (21) it eats many mice. Seton (143) states it feeds on isopods,
earthworms, etc. Its enemies are hawks, lynxes, and weasels.

Franklin's ground squirrel (Citellus franklini Sab.) burrows into the
ground deeper than the ground squirrel of the prairies, but is otherwise
similar in habits. It is gregarious and stores grain for winter. The
chipmunk (Tamias striatus griseus Mear.) is a typical forest margin
animal. It nests in the ground, as a rule in burrows about 6 to 10 ft.
long and running diagonally down to a depth of 2 to 3 ft. (21). It stores
nuts for winter. The jumping mouse (Zapus hudsonius Zim.) is one of
the most characteristic residents; it moves by great leaps and steers its
flight with its tail. The woodchuck should probably be counted here,
though it belongs deeper in the forest than any of the others. The weasel
is common in this situation, though it is perhaps more abundant along
streams (Wood).

The ground stratum supports many of the small animals of the
adjoining forest, such as centipedes, camel crickets, etc. The cottontail
is one of the chief residents, as it usually breeds in such situations. The
common shrew (Sorex personatus St. Hil.) (21) breeds on the ground, in
stumps, etc. All of the mammals recorded in the preceding stratum
feed here when suitable food is present. A considerable number of
mammals commonly regarded as belonging to the forest are said to prefer
thickets. The Virginia deer is one of these. It is probable that the elk
was somewhat similar in habits.

The bobwhite and mourning dove (occasionally) breed in these situ-
ations, the former often falling a victim to the weasel (Wood). The
high forest margin was probably a favorite location for the huts of the
aborigines. Some of the early travelers record huts around the edges of
the prairies. Such locations would supply shelter and firewood, etc., as
well as sunshine.

2. FIELD AND SHRUB STRATA

Here the ground-cherry, milkweed, and thistle have a characteristic
fauna. On the milkweed are the larvae of the monarch butterfly, the

270

THICKET COMMUNITIES

milkweed beetle (Tetraopes tetraophthalmus Forst.) (40, p. 136), and the
leaf-beetle (Doryphora clivicollis) ; the latter is very characteristic. The
milkweed flowers attract hosts of flies which are preyed upon by vari-
ous digger-wasps; bees are numerous, gathering honey. The ground-

268 269

Fig. 268. — The four-lined leaf-bug (Poecilocapsus Uneatus); a, adult; b, c, imma-
ture forms; 5^ times natural size (from Lugger).

Fig. 269. — A long-legged fly (Psilopodinus sipho Say) ; enlarged (from Williston
after Lugger) .

270 271

Fig. 270. — A large robber-fly (Dasyllis sp.); natural size (from Williston after
Kellogg).

Fig. 271. — A syrphus fly (Eristalis tenax); i| times natural size (from Williston
after Kellogg).

cherry is the food plant of the "Spanish fly" (Epicuata) and the
Colorado potato-beetle. On the thistle we find the larvae of the cos-
mopolitan and painted-lady butterflies (Pyrameis hunter a Fab. and
cardui Lin.). One of the most characteristic bugs is the 4-lined

DRY FOREST MARGIN

271

272

i^jj

#X

!•

r^Jl

BBPsf".''' •• --j

*"*«>«&l*j

^3

273

Fig. 272. — A leptid fly {Coenomyia ferruginea); enlarged (after Williston).

Fig. 273. — A large syrphus fly {Milesia virgitiiensis) ; enlarged (after Williston).

272

THICKET COMMUNITIES

leaf-bug (Poecilocapsus lineatus) (Fig. 268). The long-legged fly
(Fig. 269), the large robber-fly (Fig. 270), the common syrphus fly
(Eristalis tenax) (Fig. 271), a leptid fly (Fig. 272), and Milesia virginien-
sis (Fig. 273) visit the flowers in numbers. The garden spider occurs;
also high in the shrubs is the brilliant Epeira gigas found also in the
forest openings. The goldenrod gall-forming fly (Straussia longipennis)
(Fig. 274) with its beautifully marked wings is common. Professor

274

-Tf>,

r\x

' ..." \

/x§li

t

// /m /

*
\

y ft/ '"^thf-

\

V"

275

276

Fig. 274. — The goldenrod gall-fly (Straassi longipennis); much enlarged (from
Williston after Kellogg).

Fig. 275. — One of the crane-flies (Helobia hybrida) ; enlarged (from Williston after
Lugger).

Fig. 276. — The tree-cricket (Oecanthus fasciatus); twice natural size (after
Lugger).

Williston states that the crane-fly (Helobia hybrida) (190) (Fig. 275)
occurs. Several leaf-bugs occur; the dusky leaf-bug is common.

Several species of Orthoptera are characteristic. Of the tree-crickets
several occur among which are Oecanthus nivens DeG. and angustipennis
Fitch and fasciatus (Fig. 276). Two or three katydids occur; the
round-winged (Amblycorypha rotundi folia Scud.) is most characteristic.

DRY FOREST MARGIN

273

The grape often grows in these situations, and is especially subject to
attack by the Phylloxera (Fig. 277) and the grapevine June beetle, the
larvae of the 8-spotted forester (Alypia octomaculata Fabr.), and the
grapevine epimens (Psychomorpha epimensis Drury) (163). All of these
spend a part of their lives in the ground. The Phylloxera (Fig. 277)
winters on the roots of the grape. The grape-beetle larva bores in wood.
The pupae of the two moths bore into rotten wood or the ground for
pupation and also to spend the winter. This may be an important cause
for their presence in the forest margin. Brownie-bugs are common
(Fig. 278).

-- *0~j^%L ^Zzpcc

Fig. 277. — The grapevine Phylloxera (Phylloxera vastairix Planch.) : a, leaf galls;
b, section of gall with mother louse at center with young clustered about; c, egg;
d, nymph; e, adult female; /, same from side; a, natural size, others much enlarged
(after Marlatt, Div. Ent., U.S. Dept. Agr.).

One of the most interesting forms found here is Mantispa brunnea
(Fig. 279). This is a neuropterous insect w T ith forelegs adapted for
seizing prey. Its larva is a parasite in the egg-cases of spiders. The
adult appears in July. In the autumn, after the leaves have fallen, one
sees many nests of spiders on the high forest margin shrubs, so the young
parasites have a good chance to secure their best food conditions here.

Hawthorns often occur, and on the trunks we rind woolly plant-lice
{Schizoneurd) in great white clusters (150). The hawthorn supports
many of the pests of the apple.

274

THICKET COMMUNITIES

The birds of the high forest margin are numerous (191). The gold-
finch builds a nest of thistledown, grasses, etc., on shrubs or low trees.
The chipping-sparrow builds its nest of rootlets and lines it with
horsehair. The Baltimore and orchard orioles nest in trees and high
shrubs and feed in the open. The field sparrow sometimes builds-
on the rank weeds, in other cases on shrubs near the ground. The
mourning dove, the indigo bunting, and the yellow warbler nest on
shrubs; the latter often builds near water. The redstart builds in the
forks of bushes and trees. The loggerhead shrike is common. The
sparrow-hawk nests in deserted woodpecker holes near the edge of the
woods and feeds in the meadow or prairie. The flicker is similar in

Fig. 278. — A brownie-bug (Enchenopa
binotata Say) ; enlarged (after Lintner) .

Fig. 279. — One of the Mantis-like
neuroptera (Mantispa brunnea) ; enlarged.

habits, but uses holes of its own making. The bronzed grackle and
sharp-shinned hawk nest in trees near the forest edge and feed in the
prairie. The cowbird, which lays its eggs in the nests of other birds,
often chooses those nests of the high forest margin.

IV. General Discussion

The forest margin, as we have seen, possesses in addition to the char-
acteristic species a considerable number of species which frequent the
prairie or forest; our list includes the breeding species. The classifica-
tion below shows the various types of habit in birds and mammals.

Forest Margin Birds and Mammals
(Compiled from literature cited)
H indicates high forest margin; L, low forest margin.
A. Breeding in the ground under the shrubs; feeding in the meadows or
prairies and woods.

1. Mammals: Skunk (H), Chipmunk (H), Franklin ground squirrel (H),
Jumping mouse (H). Feed chiefly in woods.

2. Birds: No birds have this habit.

THICKET ANIMALS 275

B. Breeding on the ground among the shrubs and feeding in the open meadows
or prairies.

1 . Mammals : Common shrew (Sorex personatus) (L) , the cottontail (H) .

2. Birds: Bobwhite (H), mourning dove (H) sometimes, northern yellow-
throat (L) sometimes, song sparrow (L) sometimes.

C. Breeding on the shrubs and feeding in the forest edge and sometimes in
the open meadows or prairies.

1. Mammals: None.

2. Birds: (a) Low forest margin: song sparrow, goldfinch, indigo bunting,
northern yellowthroat, brown thrasher, and catbird.

(b) High forest margin: goldfinch, lark sparrow, chipping-sparrow,
field sparrow, indigo bunting, yellow warbler, redstart, loggerhead
shrike, mourning dove, catbird, cowbird, bronzed grackle, brown
thrasher.

D. Breeding in the trees of the forest and feeding in the prairies.

1. Mammals: raccoon.

2. Birds: Sparrow-hawk, sharp-shinned hawk, and several other hawks,
flicker, bronzed grackle, Baltimore oriole.

The list shows animals which breed in the margin of woods and often
feed not only there but in the prairies. Similar relations were noted by
Bates in the savannas along the middle Amazons. The advantage of the
forest margin lies in the facts of: (1) shade for the nocturnal and crepus-
cular forms; (2) abundant space in the thickets for nests; (3) large stiff
plants which accommodate the large animals : (a) places for the spiders to
stretch their nets; (b) plants large enough for the roosting- and nesting-
places of birds and larger insects; (4) protection from wind and from
winter freezing afforded by the forest. From the standpoint of food
relations many forest margin animals must be counted in with the
prairie forms.

One of the most striking facts concerning the forest margin animals
is (a) their wide distribution and (b) their survival under agricultural
conditions. Many animals of importance as crop pests belong to forest
edges rather than to the forest proper. They take possession of the road-
sides when the country is cleared. Their distribution is a function of
the forest margin type of habitat. While it is a characteristic feature
of the forest border area, it is also to be found extending along the
wooded streams into the great plains and toward the east through the
forest area, as the shrubby bluff, the creek and river margin, the fired
area, and the marsh margin. While local and always leading a precari-
ous existence in unstable situations, this type of community, probably

276

THICKET COMMUNITIES

by virtue of its adaptation to such conditions, has given us a very large
number of animals of very considerable economic importance. Tables
LXIII and LXIV indicate the forms which we have found coir mon to
the forest margins and other situations.

TABLE LXIII

Animals Recorded for a Moist Low-Ground Forest Margin or Thicket Near
Wolf Lake (Station 45)
The names that are starred represent animals that have been recorded from the
shrubs and weeds along the margins of bogs, lakes, ponds, and streams, June 15 to
August 30.

Common Name

Scientific Name

Orb-weaving spider

Jumping spider

*Garden spider

*Long-bodied spider

*Orb-weaving spider

*Orb-weaving spider

Black-sided locust

Tree-cricket

Fork- tailed katydid

Nebraska conehead

*Robust lubberly locust . .
*Red-legged grasshopper .

*Grasshopper

*Oblong-winged katydid . .

Long-horned grasshopper

Coreid

Candlehead

Stinkbug

*Four-lined leaf-bug

Coreid

Solitary wasp

*Buff alo tree-hopper

Long-legged bug

*Ambush-bug

*Plant-bug

*Tarnished plant-bug ....

Flower ground beetle . . .

* Willow-beetle

Willow-borer

Elm-borer

Introduced beetle

*Goldenrod beetle

Fork-tailed larva

* Wasp

*Jug-making wasp

*Sawfly

Swallowtail

*Maia larva

Singa variabilis Em.

Attus palustris Peck.

Argiope aurantia Lucas

Tetragnatha laboriosa Htz.

Epeira trivittata Key

Epeira trifolium Htz. (rare)

Xiphidium nigro pleura Bruner

Oecanthus fasciatus Fitch

Scudderiafurcata Bruner

Conocephalus nebrascensis Bruner

Melanoplus diferentialis Thos.

Melanoplus femur-rubrum DeG.

Melanoplus bivittatus Say

Amblycorypha oblongifolia DeG.

Orchelimum indianense B latch.

Protenor belfragei Hagl.

Scolops sulcipes Say

Euschistus fissilis Uhl.

Poecilocapsus lineatus Fab.

Corynocoris distinctus Dal.

Odynerus tigris Sauss

Ceresa bubalus Fab.

Neides muticus Say

Phymata erosa fasciata Gray

Adelphocoris rapidus Say

Lygus prat ens is Linn.

Call i da punctata Lee.

Lina scripta Fab.

Saperda concolor Lee.

S a per da lateralis Fab.

Cryptorhynchus lapathi Linn.

Trirhabda tormentosa canadensis Kirby

Centra sp.

Polistes variatus Cress.

Eumenes fratemus Say

Cimbex americana Leach.

Papilio cresphontes Cram.

Hemileuca maia Dru.

THICKET ANIMALS
TABLE LXIV

277

Animals Recorded from the Medium Moist or Climatic Forest Edge or
Thicket at Riverside, III. (Station 48)
Those starred have been taken from weedy and shrubby roadsides and identified
by specialists. According to the author's field identification nearly all should be
starred.

Common Name

Scientific Name

Month

Crab-spider

Jumping spider

Spider

Spider (Dictynidae)

*Orb-weaving spider

Spider

Spider

Texas grasshopper

Spittle insect

Leaf -hopper

Four-lined leaf -bug

Leaf -bug

Leaf -bug

Stinkbug

Long-horned beetle

Long-horned beetle

Tortoise beetle

Tortoise beetle

♦Old-fashioned potato-beetle
♦Goldenrod blister beetle . . .

Dock curculio

Leaf-beetle

Beetle {Erotylidae)

Beetle (Erotylidae)

♦Beetle.

*Grapevine beetle

♦Milkweed leaf-beetle

Ground beetle

Oak-pruning twig-borer . . .

Flower beetle (Carabidae) .

Lantern-fly

Wasp

Bee (Halictidae)

Crane-fly

Crane-fly

Fly

Goldenrod gall fly

Runcinia aleatoria Htz

Maevia niger Htz

Pisaurina undata Htz

Dictyna foliacea Htz

Epeira trifolium Htz

Atypus milberti Walck

Clubiona obesa Htz

S cudder ia texensis S. and P

Clastoptera proteus Fitch

Diedrocephala coccinea Forst

Poecilocapsus lineatus Fab

Stiphrosoma stygica Say

Jlnacora stalii Reut

Podisus maculiventris Say

Oberea tripunctata Sw

Dectes spinosus Say

Coptocycla bicolor Fab

Coptocycla signifera Herbst

Epicauta marginata Fab

Epicauta pennsylvanica DeG

Lixus macer Lee

Chelymorpha argus Herbst. . .

Languria angustata var. trifasciata Say

Aero pier ys gracilis Newm

Odontota nervosa Panz

Pelidnota punctata Linn

Doryphora clivicollis Kirby

Lebia atriventris Say

Elaphidion villosum Fab

Callida punctata Lee

Megamelus marginatus Van D

Crabro interruptulus D.T

Chloralictus cressoni Rob

Helobia hybrida Meig

Pachyrhina ferruginea Fab

Coenomyia ferruginea Scop

Straussia longipennis Wied

6 9

6 9

6

69

6
6
8
6
6
6
6
6
6
6 7
7
7
7
7
7

6
6
8

7 *

7 I

6

5

5

4 5

5
5
5

CHAPTER XIV

PRAIRIE ANIMAL COMMUNITIES

I. Introduction

We have noted that a part of the region about Chicago is to be
classed as savanna and that the savanna is made up of trees in groves
and along the streams, and of forest margin and prairie. Prairie may
roughly be separated into high and low. The low prairie commonly
exists in depressions in the moraine, lower places in the plain of old
Lake Chicago. They are usually covered with water in the spring.
The high prairie is above water and is dominated by different plants.
As the depressions are filled or become better drained, high prairie
plants capture the habitat.

II. Prairie Formations

We have noted that the low prairie is covered by water in spring
(Figs. 280, 281). As the water dries up, which usually occurs by the
middle of May, the prairie plants begin to grow and the prairie animals
make their appearance. This change does not take place abruptly,
but gradually. There is a succession of adult-stage animals through
the summer. This is what is known as seasonal succession.

I. SEASONAL SUCCESSION

When the snow melts in March and the frost goes out of the ground,
the salamander {Ambly stoma tigrinum) comes out of the ground and
soon deposits masses of eggs in the water. The young of Eubranchipus,
Cyclops, and rotifers appear after a few days and often reach adult size
by April 1. On April 6, 1908, Mr. Dimmit found adult Eubranchipus,
Cyclops, and rotifers in the pond south of Jackson Park. The sala-
manders had disappeared. On April 12 three species of flatworms
{Vortex viridis, Planaria velata Stringer, and Dendrocoelum) had appeared,
and the first frogs were noted. On April 14 he found frogs' eggs and
the red crustacean (Diaptomus). Eubranchipus was at its maximum
abundance. On April 19 he found Daphnidae, rhabdocoel worms, and
tadpoles. On May 3 but few Eubranchipus were found. Diaptomus was
plentiful, perhaps at its maximum abundance. Daphnidae was more
abundant than before. Planaria were near their maximum. On May 10

278

LOW PRAIRIE

279

Eubranchipus serratus had disappeared and Diaptomus was not common.
Our next record is one month later, when the grasshoppers and other
prairie or land species had begun to appear. This succession is of
annual occurrence. The temporary pond community is seasonally
succeeded by the low prairie community. Flies which breed in water,

Fig. 280. — A prairie pond, still permanent.

Fig. 281. — A temporary prairie pond in spring. The short dead grass indicates
that a crop was harvested the preceding season.

such as Scoliocentra (Fig. 282) and Tetanocera (Fig, 283), are common
(also Figs. 284, 285, 286).

LOW PRAIRIE ASSOCIATION

a) The subterranean- ground stratum (Stations 42, 43, 44, 45; Table
LXV). — Earthworms are abundant. Several of the grasshoppers de-
posit their eggs in the ground. The larvae of the click-beetle {Melanotus

28o

PRAIRIE COMMUNITIES

282

283

Fig. 282. — A low prairie fly {Scoliocentra helvola Loew); enlarged.
Fig. 283. — A low prairie fly (Tetanocera iimbrarum)\ enlarged.

LOW PRAIRIE

281

Some Low Prairie Flies
Fig. 284. — Pipunculus fuscus (after Lugger from Williston).
Fig. 285. — Tabanus lineola Fabr. (after Lugger from Williston).

Fig. 286. — Spilogaster sp. from Williston, who says it inhabits high grass.

282

PRAIRIE COMMUNITIES

fissilis), of the strawberry flea-beetle (Typophorus canellus), and the
corn rootworms (Diabrotica) (174), and of many other insects well
known in economic literature, burrow into the roots of the plants in the
larval stage. Many of the grass-eating cutworms, caterpillars, and
sawflies (Fig. 287) pupate beneath the surface of the ground. The
salamander (Ambly stoma tigrinum) spends ten months of each year buried
in the mud of such temporary ponds. The Pennsylvania meadow-mouse
(Microtus pennsylvaniats Or.) has been common in these situations.

/

Fig. 287. — Grass sawflies: a, eggs; b, larvae (a and b natural size); c, larva;
d, cocoon; e, adult male; /, adult female (c to /enlarged as indicated) (after Marlatt,
Insect Life).

The star-nosed mole burrows beneath the sod. It is remarkable for its
curiously fringed nostril. The wetness of the ground excludes other
burrowing mammals.

One of the most abundant forms found here is the snail (Succinea
avara). The ant (Formica subpolita var. neogagates Em.) is also usually
common. It builds a hill and burrows below the surface of the ground
also. Several snout-beetles, the adult click-beetles, and the short-
winged grouse locust (Tettigidea parvipennis and pennata) are common

LOW PRAIRIE

283

on the ground. The 6-spotted spider (Dolomedes sexpunctatus) preys
upon the other small animals. The common toad and the marsh tree-
frog (Chorophilus nigritus) are common (139). The latter is particularly
abundant in the autumn. Its eggs are laid in April in the temporary
pools. Transformations are complete by the last of May. The prairie
garter-snake {Thamnophis radix) was formerly common. It is known to
feed upon the swamp tree-toad. The prairie water-snake (Tropidonotus
grahamii) was formerly common in and about prairie sloughs (22).

The bobolink builds a nest here in a bunch of grass; the meadow
lark and dickcissel build nests of grass and weeds, usually arched over.
The bisons, residents of the high prairie, were fond of rolling in the low

r

288

Fig. 288. — The large green leaf-hopper
(Draeculacephala mollipes) : a, young; b, one
half -grown; c, adult; enlarged as indicated
(after Forbes).

Fig. 289. — The six-spotted leaf hopper
(Cicadida sexnotata); enlarged as indicated
(after Forbes).

iM*F

|#

w.

289

wet places on the prairie and covering themselves completely with mud.
This must have destroyed numbers of pond animals and badly disturbed
others.

b) The field stratum (Stations 42, 43, 44, 45; Table LXVI). — This
is the chief stratum. While various conditions of the subterranean
and ground strata, depending upon nearness to ground water, could be
recognized, our studies have not been sufficiently detailed to warrant
attempts at separation. A girdle of bulrushes can, however, often be
distinguished.

Bulrush girdle : Two of the large green leaf-hoppers {Draeculo-
cephala mollipes [Fig. 288] and Cicadula 6-notata [Fig. 289]) are common.
The damsel-bug (Reduviolus ferus), which feeds upon leaf-hoppers, is

284

PRAIRIE COMMUNITIES

sometimes taken. The slender meadow grasshopper (Xiphidium fascia
taum) is common, but breeds in the sedge zone. A flea-beetle (Monachus
saponatus), the 12-spotted Diabrotica (Diabrotica 12-pundata) (156),
and the salt-meadow snout-beetle (Endalus limatulus) (156) are the
chief beetles.

The spiders (Epeira trivittata and Tetragnatha laboriosa) are common.

The flies of this girdle are perhaps the most noteworthy insects. Several

species of brownish or yellowish flies with conspicuously marked wings

are nearly always common. They are Sciomyzidae (Tetanocera plumosa

and umbrarum) (Fig. 283). Other characteristic

flies are Osinidae (Chlorops sulphur ea Leow.),

midges, mosquitoes, Dolichopodidae,Drosophilidae,

and Anthomyidae. The blue and yellow moth

(Scepsis fulvicollis) is common.

Boneset and sedge girdle: The buffalo tree-
hopper (Ceresa bubalus) (Fig. 259) is found here.
The dusky (Fig. 261) and tarnished plant-bugs
(Fig. 262) suck the juices of the mint and other
plants. The ambush-bug and the damsel-bug
often lie in wait in the blossoms for prey.

290

Fig. 290. — Larva of the salt-marsh caterpillar (Estigmena acraea Dru.); natural
size (after Forbes).

Fig. 291. — Adult female of the same; natural size (after Forbes).

Aphids occur and with them are the syrphus flies, lady-beetles,
and other aphid enemies (164), which are discussed more fully in
connection with high prairies. The bright green beetle [Chrysochus
auratus) feeds on the small-leafed milkweed. One of the corn "bill-
bugs" (174) or snout-beetles {Sphenophorus pertinax Oliv.), another
snout-beetle (Cryptocephalus venustus), common garden pests, as well as
the leaf-beetle (Typophorus canellus) are common (174).

One of the most characteristic groups of the low prairie is that of the
grass-feeding larvae. The first of these to appear in spring is the grass

LOW PRAIRIE

285

sawfly (Fig. 287), which is very abundant in early June. Asscoiated
with this are many caterpillars (174). The greasy cutworm (Agrotis
ypsilon Rott.) feed supon the strawberry. The army worm (Leucania
unipuncta Haw.) feeds upon a variety of plants, and several of its near
relatives occur. The larvae of the salt-marsh caterpillar (Estigmene
acraea) (Figs. 290, 291), the yellow bear (Diacrisia virginica Fab.) (Fig.
292), hedgehog caterpillar {Isia Isabella S. and A.), and Apantesis
phalterta Harr. are common.

Of the Orthoptera, X iphidium fasciatum and the 2-lined locust (Melano-
plus bivittatus), the red-legged locust (Melanoplus femur-rubrum) , and
the short-winged brown locust (Stenobothrus curtipennis) (Fig. 293)
are most characteristic.

Fig. 292. — The yellow bear: a, larva;
b, adult (Diacrisia virginica Fabr.); nat-
ural size (after Forbes).

Fig. 293. — The short- winged brown
locust (Stenobothrus curtipennis) (after
Lugger).

On the flowers are many flower-frequenting flies, viz., Sparnopolius
flavins Wied., Asilus sp., Syritta pipiens Linn., Coenosia spinosa Walk.,
Paragus angustifrons Loew., Pachryrkina ferruginea, and Helophilus
conostoma Will. Preying upon the various insects are the mud-dauber
wasp {Scelipron cementarius) and the digger-wasp (Ammophila nigricans).
Parasites, such as Ichneumon zebralus, Paniscus gemminatus, Epeolus
cressonii, etc., occur upon the plants, and certain of them are often
found engaged in depositing eggs in or on caterpillars. The onion-fly
(Tritoxa flexa) (190) is striking because of its black body and black
wings, obliquely marked with white.

Spiders, especially crab spiders, are abundant. The white Misumena
vatia occurs on the milkweed and the flowers of the mint. Epeira
trivittata and the long-bodied spider {Tetragnatha labor iosa) occur on the
blossoms and stems of various plants.

286 PRAIRIE COMMUNITIES

HIGH PRAIRIE ASSOCIATION

(Stations 47, 48; Table LXVII) (Fig. 294)

The type of vegetation which dominates the high prairie is most
noticeably characterized by the silphiums — the rosin-weed and the com-
pass plant. The former has broad undivided leaves, the latter divided
leaves which usually face east and west. This plant formation springs
up throughout the temperate American forest border area on all well-
drained ground. It succeeds the low prairie as the depressions occupied
by the latter are rilled or drained. The high prairie then succeeds the
low prairie just as the bulrushes succeed the pond plants; the sedges,
the bulrushes; and the boneset association, the sedges. All stages in
the development of a pond into prairie may be found near Chicago.
Dr. Cowles is of the opinion that shallow ponds with gently sloping
sides develop into prairie, while deeper ponds with steep sides develop
into forest.

a) Subterranean- ground stratum. — Earthworms abound. The larvae
of the May-beetles and other Scarabaeidae are abundant, feeding on the
roots of the prairie plants. The May-beetle is often parasitized by a
wasp larva (Tiphia vulgaris) (Fig. 297, p. 289) (189). The eggs of the
2-lined locust (Melanoplus bivittatus) are deposited here in the ground.

The 13-lined ground squirrel (Citellus ij-lineatus) (21) is a slightly
gregarious species, strictly diurnal, staying in during dull and cloudy
days. Its burrows are from 3 to 16 in. below the surface, and often have
five or six entrances into a larger cavity lined with grass. In a den
studied by Thompson-Seton the nest was centrally located. Food,
which includes cabbage butterflies, cutworms, grasshoppers, beetles,
ants, birds (shore lark and lark bunting), and vegetation, is carried in
the cheek pouches and stored. The species is non-social. A brood of
about eight young are produced in April.

The prairie deer-mouse {Peromyscus bairdii H. and K.) (21) is still
probably common. According to Thompson-Seton (143) its home range
is about 100 yds. It is neither social nor gregarious. It is strictly
nocturnal and active all winter, though some seeds are stored. Its
food is chiefly seeds. Hawks and owls frequently prey upon it.

Of the extinct forms several are characteristic. The coyote (Canis
latrans Say) was formerly common. According to Thompson-Seton
(143), its home range is ten miles. The den is in a bank or an abandoned
badger hole. The nest is a cavity 3 ft. in diameter, with an air-shaft.
It is not so social as the gray wolf. Three to ten young are produced

HIGH PRAIRIE

287

288

PRAIRIE COMMUNITIES

in April and are fed on disgorged food by the mother. The food con-
sists of ground squirrels, mice, rabbits, frogs, birds, and grasshoppers.

The badger (Taxidea taxus Schr.), according to Thompson-Seton,
digs a U-shaped burrow with two openings about 6 ft. deep. It is a
very rapid burrower. It is nocturnal, but basks in the sun at the
mouth of its burrow and hibernates. Its food consists of mice and
ground squirrels.

The pocket gopher (Geomys bur sarins Shaw), according to Thompson-
Seton, makes a burrow 3 in. wide. It burrows with its feet and when

Fig. 295.— The nest and eggs of the prairie chicken. Photo by T. C. Stephens.

a pile of dirt has been loosened, turns about and forces it to the exterior
with its head. The coyote sometimes rears its young in badger holes on
the prairies.

On the ground we find ants (Myrmica rubra scabrinodis) , one thou-
sand of which were found by Judd (191) in the stomach of a single night-
hawk. Ground beetles are common. Crickets, spiders, and weevils
all frequent the ground. Most of the field stratum species hibernate
on the ground under the fallen plants.

The common toad is rarely wanting near water. The garter-snake
{ThamnopMs radix) has been recorded by Ruthven (156) from such

HIGH PRAIRIE

289

situations in Iowa. The green snake (Liopeltis vernalis) is the most
characteristic reptile. The prairie rattlesnake or Massasauga (Sis-
trurus catenatus) was formerly common (22).

Eight nesting birds, all of which are quite familiar to everyone, occur.
The bobolink nests in a bunch of grass. It feeds upon flea-beetles,
weevils, ants, bees, wasps, and grasshoppers of the field stratum. The
meadow lark feeds on parasitic hymenoptera, including the parasite of the
May-beetle, ground beetles, crickets, grasshoppers, weevils, spiders, etc.
The dickcissel is similar in habits. The grasshopper sparrow feeds on
long-horned grasshoppers, flea-beetles, cutworms, and parasitic hymen-
optera. The vesper sparrow feeds upon moths, flies, ants, beetles,
grasshopper eggs, etc., and grain and weed seeds. The nighthawk
builds no nest, flies at twilight, and feeds chiefly upon ants. The

296

Fig. 296 — The adult of the wasp which
is parasitic on the May-beetle grubs
(Tiphia vulgaris) (after Forbes).

Fig. 297. — The larva of the same (after
Forbes).

prairie chicken is the most characteristic bird. Its nest is a simple
hollow in the grass (Fig. 295). The prairie horned lark builds a nest
lined with thistledown and feathers. The lark bunting nests in a tuft
of grass.

All of the mammals noted in the subterranean stratum should be
added here, as nearly all of them feed largely in the ground and field
strata.

The field-mouse (Microtus ochrogaster Wagner) (21) is a resident of
the ground stratum. Its nest is a pile of grass fragments on the ground.
The species feeds chiefly upon grasses and cultivated plants. The
bison {Bison bison Linn.) is the most characteristic mammal. Thompson-
Seton says that the bison population of North America was originally
75,000,000. This animal generally went in clans or families which are
said to have had characteristics of their own. An old cow was the

290

PRAIRIE COMMUNITIES

usual leader of the clan. On the great plains these united
and formed the larger herds of 20,000 to 4,000,000 or more,
which have been described by travelers. The males aided
in defending the young. The cowbird is said to have fol-
lowed the herds constantly.

b) Field stratum. — The lepidopterous larvae are similar
to those of the low prairie, but much less numer-
ous. The hymenoptera are represented by Bom-
bus separatus, and many of those recorded on the
low prairie. The adult of the parasite (Tiphia
vulgaris) of the May-beetle larva
(Figs. 296-97) occurs commonly.
Several species of aphids (Figs.
298-300) occur, especially on the

A

milkweeds and thistles.
These are commonly at-
tended by ants, which
stroke them and secure the honey dew from
the posterior ends of their alimentary canals.
The aphids reproduce rapidly, the young being
born in rapid succession at a very ad-
vanced state of development. They
\ begin sucking the juices of the plant
"\ at once. Several small parasitic

\ hymenoptera (braconids) (Fig.

\ 299) lay their eggs in the be dies

of the aphids. These finally kill
- A the aphids, whose bodies with

Fig. 298. — A viviparous grain louse (Macrosiphum granaria Kirby) with her
newly born young on a barley leaf (after Washburn, Bull. 108, Minn. Agr. Exp. Sta.,
Fig. 2, p. 262).

X

HIGH PRAIRIE

291

300

Fig. 299. — A parasitic wasp depositing
eggs in the body of a grain louse (after
Washburn, Bull. 108, Fig. 16, p. 274).

Fig. 300. — A louse killed by a parasite
(after Washburn, loc. cit., Fig. 12, p. 276).

Fig. 301. — The life history of the golden-eyed lacewing (Chrysopa oculata):
o, eggs; b, the larva — "aphis-lion"; c, foot of the larva; d, the larva seizing an aphid;
e, the pupal cocoon; /, g, h, the adult; h, natural size (after Chittenden, Div. Ent.,
U.S. Dept. Agr.).

292 PRAIRIE COMMUNITIES

small circular openings on the abdomen can often be seen sticking to
the food plant (Fig. 300). The aphis-lion, which is the larva of the
golden-eyed lacewing, feeds upon them (Fig. 301). The eggs of the
lacewing are peculiar in that each is attached to a stalk. This is
supposed to be an adaptation preventing the larvae already hatched
from devouring the remaining eggs. The larva of the syrphus fly
(Mesogramma sp.) (Fig. 302) devours the aphids in numbers. Lady-
beetles, both adults and larvae (Hippodamia parenthesis Say, Megilla
maculata) (Fig. 303), eat aphids.

In June the narrow leaf-bug (Miris dolobrata) and the dark leaf-bug
(Horcias goniphorus) are usually very abundant; both are characteristic.

Fig. 302. — A syrphus fly {Mesogramma polita), adult (after Forbes): a, the
larva which feeds on aphids; b, pupa; enlarged as indicated (from Forbes after
Riley and Howard, Div. Ent., U.S. Dept. Agr.).

Later in the season their places are taken by several others (Lygus
pratensis and Adelphocoris rapidus). The garden flea-hopper (H alliens
uhleri) occurs on the under side of leaves. The squash-bug family is
represented by Alydus cons per sus.

The tree-hoppers are represented by the buffalo tree-hopper (Ceresa
bubalus), and the curve-horned tree-hopper (Campylenchia curvata).
The only lantern-fly recorded is Amphiscepa bivittata. Leaf-hoppers are
numerous; about ten species have been taken.

The species of Orthoptera are mainly different from those of the low
prairie. The 2-lined and short-winged brown locusts still continue.
Xiphidium strictum (Fig. 304) takes the place of fasciatum. The com-
mon meadow grasshopper (Orchelinium vulgare) and an occasional Texas

HIGH PRAIRIE

293

katydid (Scudderia texensis) are taken from the goldenrod. From the
goldenrod we also take the goldenrod beetle (Trirhabda tormentosa
var. canadensis) and the case-bearer (Pachybrachys). The lady-beetles
(Cycloneda, Hippodamia, Megilla, etc.) are common. The clover-leaf
beetle (Languria mozardi?) (Fig. 305) is also of common occurrence.
The snout-beetles are represented by the large, elongated Lixus (Fig.
306), the larvae of which feed in the stalks of rank weeds.

Fig. 303. — The lady-beetle {Megilla macidata DeG.) and its life history: a, larva;
b, pupa; c, adult (Chittenden, U.S. Dept. Agr.); enlarged as indicated.

Fig. 304. — Meadow grasshopper {Xiphidium strictum Scud.);
(after Forbes).

twice natural size

The onion-fly occurs in connection with the prairie onion. Eris talis
tenax is common on the flowers. Various flower-flies occur. Waiting
in the flowers for such animals as may come are the ambush-bugs (Phy-
mata erosa fasciata), and the crab spiders (Misumessus asperatus and
Runcina ahatoria). The jumping spiders (Phidippus podagrosus) are
also predatory (138). The orb -weavers (Epeira trivittata, Agriope
trifasciata) build webs into which many insects fall.

2 9 4

PRAIRIE COMMUNITIES

W mammm

.J

■ ■■" ! V. 1

i

1

Fig. 305. — The clover-stem borer (Languria mozardi Lee) : a, the egg; 6, c, the
larva; J, the pupa; e. the adult; much enlarged (after Folsom from Forbes).

PRAIRIE ANIMALS
III. General Discussion

295

One of the striking peculiarities of the prairie formation is the almost
complete cessation of life activities of all the smaller animals in winter.
In this respect the prairie animals follow the plants. In spring we find
chiefly the insignificant seedling that has sprouted from bulb or seed,
and the nymph that has just hatched from the egg. As the season
advances the plants become adult, the majority of these reaching
maturity with the animals in midsummer.

Fig. 306. — The dock curculio (Lixus concavus Say) : a, adult; b, egg; c, d, newly
hatched and full-grown larva; e, pupa; /, tip of pupa from above; about twice natural
size (from Forbes after Chittenden, Div. Ent., U.S. Dept. Agr.).

The low prairie is of interest because of its relation to the eastern
forest region. Many if not most of the low prairie forms probably
originally occurred in the marshes of the eastern forest region and the
river-bottom swales of the prairie and great plains. Many of them
(such as place their eggs into plants) are quite independent of the ground,
and therefore are most likely to survive under conditions of cultivation
where mesophytic plants are favored and the cultivation of the soil
does not interfere with their activities.

296

PRAIRIE COMMUNITIES

TABLE LXV
Low Prairie Animals Inhabiting the Ground
R = Riverside (Station 48); W=near Wolf Lake (near Station 45); J = south of
Jackson Park (Stations 42, 43).

Common Name

Crayfish

Crayfish

Ground beetle . .
Ground beetle . .
Ground beetle . .

Spider

Beetle

Shorebug

Salamander. . . .

Frog

Cricket-frog. . . .
Swamp tree-frog

Toad

Garter-snake. . .

Scientific Name

Cambarus diogenes Gir

Cambarus gracilis Bun

Chlaenius aestivus Say

Platynus affinis Kirby

Amara angustata Say

Ozyptila cons pur rata Thor . . .

Diplochila laticollis Lee

Salda coriacea Uhl

Ambly stoma tigrinum Green. .

Rana pipiens Sch

Acris gryllus Lee

Chorophilus nigritus Lee

Bufo lentiginosus Shaw

Thamnophis radix B. ar.d G.?

Habitat

W

w
w
w

TABLE LXVI
Low Prairie and Temporary Marsh Animals Frequenting the Vegetation
B = the triangular bulrush belt about Wolf Lake (Station 45); S = the sedge
belt of the same; J = sedge prairie south of Jackson Park (Stations 42, 43); R = sedge
prairie near Riverside (Station 48), June 15 to August 30.

Common Name

Spider

Diving spider

Spider

Long-bodied spider. . . .

Crab spider

White crab spider

Striped spider

Garden spider

Small orb-weaver

Tube- weaver

Slender meadow grass-
hopper

Short- winged brown lo-
cust

Meadow grasshopper. .

Red-legged grasshopper

Scientific Name

Eugnatha straminea Em

Dolomedes sexpunctatus Htz. . .

Epeira trivittata Key

Tetragnatha laboriosa Htz

Runcinia aleatoria Htz

Misumena vatia Clerck

Argiope trifasciata Forsk

Argiope aurantia Luc

Epeira trifolium Htz

Agelena naevia Walck

Xiphidium fasciatum DeG ....

Stenobothrus curtipennis Harr. .

Orchelimum vidgare Harr

Melanoplus femur-rubrum DeG

Habitat

B

B

B

S

T

B

S

J

s

J

J
J

B

s

J
J

B

s

J

R

s

T

R

s

J

s

J

R

PRAIRIE ANIMALS
TABLE LXVI— Continued

297

Common Name

Texas grasshopper ....

Cockroach

Cricket

2-lined locust

Green-legged locust . . .

Capsid bug

6-spotted leaf -hopper . .
Large leaf-hopper .....

Damsel-bug

Leaf-hopper

Leaf-hopper

Leaf-hopper

Leaf-hopper

Tarnished plant-bug. . .

Brownie bug

Dusky plant-bug

Leaf-hopper

Ambush-bug

Long-horned leaf-beetle
Cornroot worm-beetle.
Marsh snout-beetle. . . .

Buprestid

Leaf-beetle

Click-beetle

Green beetle

Chrysomelid

Chrysomelid

Case-bearer

Milkweed beetle

Goldenrod beetle

Snout-beetle

Fly

Cloudy- winged fly ... .

Long-legged fly

Syrphus fly

Onion-fly

Ant

Syrphus fly

Bee

Bumblebee

Lacewing

Ant

Ichneumon fly

Moth

Syrphus fly

Social wasp

Scientific Name

Scudderia texensis S. and P . .

Blattid sp

Nemobius maculatus Blatch. .
Melanoplus bivittatus Say. . . .
Melanoplus viridipes Scud. . .

Tcratocoris discolor Uhl

Cicadula sexnotata Fall

Draeculacephala mollipes Say .

Reduviolus ferus Linn

Chlorotettix unicolor Fitch. . . .
Helochara communis Fitch . . .

Athysanus striolus Fall

Chlorotettix tergata Fitch

Lygus pratensis Linn

Campylenchia curvata Fab . . .
Adelphocoris rapidus Say. . . .
Athysanus parallelus Van D . .
Phymata erosa fasciata Gray .

Donatio, subtilis Kunze

Diabrotica 12-punctata Oliv . .

Endalus limatulus Gyll

Acmaeodera pulchella Hbst. . .
Monachus saponatus Fab. . . .

Mclanotus fissilis Say

Chrysochus auratus Fab

Nodonota tristis Oliv

Typophorus canellus aterrimus

Oliv

Cryptocephalus venustus Fab.
Cryptocephalus cinctipennis

Rand

Tetraopes tetraophthalmus Forst
Trirhabda canadensis Kirby. .

Desmoris scapalis Lee

Telanocera umbrarum Linn . .
Tetanocera plumosa Loew. . . ,

Dolichopodidae sp

Syrphus americanus Wied. . . .

Tritoxa flexa Wied ,

Formica subpolita neogagates

Emery

Eristalis tenax Linn

Agapostemon viridulus Fab. . ,

Bombus separatus Cress

Chrysopa albicornis Fitch .....
Myrmica rubra scabrinodis Nyl
Ichneumon galenus Cress

Scepsis fidvicollis Hbn

Meso gramma geminata Say. . . .
Polistes variatus Cress

Habitat

S

S

J

S

J

S

J

s

J

B

s

I

B

s

T

B

s

T

B

s

J
J
I

B

s

r

s

J

s

J

B

s

J
I

s

J

B

B
B
B

s
s

J

B

s

J

s

f

s

J
J

B
B

s

J
J

J
J
J
J
J
J

s

J

s

J

J

B

s

J
J
J
J
J
J

s

J

s

J

298

PRAIRIE COMMUNITIES

TABLE LXVII

Animals Usually Common on Compass-Plant Prairie
Collections made near Riverside (Station 48) and Chicago Lawn (Station 47),
June 15 to August 30.

Common Name

Scientific Name

Cricket

Jumping spider

Jumping spider

Jumping spider

Jumping spider

Harvestman

Garden spider

Ant

Grasshopper

Meadow grasshopper
Meadow grasshopper

Brown locust

Conehead

Katydid

Leaf -hopper

Leaf-hopper

Leaf -hopper

Leaf-bug

Leaf-bug

Leaf-hopper

Membracid

Garden flea-hopper . .

Stinkbug

Leaf-bug

Leaf-hopper

Leaf-hopper

Negro-bug

Coreid

Stinkbug

Leaf -bug

Leaf -bug

Beetle (Mordellid) . .

Lady-beetle

Case-bearer

Strawberry beetle . . .

Beetle

Syrphus fly

Green snake

Nemobius fasciatus vitlatus Harr.

Maevia niger Htz.

Phidippus podagrosus Htz.

Phidippus borealis B.

Phidippus rufus Htz.

Liobunum grande Say

Argiope trifasciata Fors.

Formica cinerea var. neocinerea Wheeler

Orphulella speciosa Scud.

Orchelimum vulgare Harr.

Xiphidium strictum Scud.

Stenobothrus curtipennis Harr.

Conocephalus ensiger Harr.

Scudderia texensis S. and P.

Alhysanus striolus Fall.

Agallia 4-punctata Prov.

Platymetopius acutus Say

Trigonotylus ruficornis Four.

Miris dolabrata Linn.

Chlorotettix spatulata O. and B.

Stictocephala lutea Wlk.

Halticus uhleri Giar.

Euschistus variolar his Pal. Beau v.

Plagiognathus politus Uhl.

Eutettix straminea Osb.

Empoasca mali LeB.

Thyreocoris pulicaria Van D.

Alydus conspersus Mont.

Cosmopepla camifex Fab.

Garganus fusiformis Say

Horcias marginalis Reut.

M ordellistena connata Lee.

Cycloneda sanguined munda Say

Pachybrachys sp.

Typophorus canelhis gilvipes Horn

Photinus punctulatus Lee.

Eristalis tenax Linn.

LiopeUis vernal is Harlan

CHAPTER XV

GENERAL DISCUSSION

I. Introduction

We have briefly presented some facts regarding the nature and
environmental relations of animals, an account of the environment, and
a discussion of the inhabitants of some of the type habitats of the forest
and forest border regions. We noted also in preceding chapters some
aspect of relations of the animals of the same and of different com-
munities to one another, and our relations to them. We may still
present (a) the relations of the different communities to one another,
(b) the laws governing distribution, and (c) a discussion of the relations
of ecology to broader geographic problems.

II. Application of the Laws Governing Animal Activities to
World and Regional Problems

As was stated in the first chapter, the relative importance of different
environmental factors is not definitely known, but probably in local and
experimental conditions, land environments can best be measured in
terms of evaporating power of the air, light, and materials for abode,
aquatic environment by carbon dioxide, oxygen, and materials for abode.
In explaining extensive or regional distribution, a few factors have
been emphasized and these usually in the sense of barriers. Merriam
(48) emphasizes temperature, Walker (128) atmospheric moisture.
Heilprin (192, p. 39), like most paleontologists, emphasizes food.
Nothing is, I believe, more incorrect than the idea that the same single
factor governs the regional distribution of most animal species. Since
the environment is a complex of many factors, every animal, while in
its normal environmental complex, lives surrounded by and responds
to a complex of factors in its normal activities (44, p. 193). Can a
single factor control distribution ?

1. reactions to single factors
Considerable physiological study of organisms has been conducted
with particular reference to the analysis of the organism itself, but with
little reference to natural environments. Many of the factors and con-
ditions employed in such experiments are of such a nature that the

299

300 ECOLOGY

animal would rarely or never encounter them in its normal life. Other
experiments are attempts to keep the environment normal, except for
one factor (44, p. 180). These have demonstrated that animals are
capable of responding to the action of a single stimulus.

A typical experiment to demonstrate this would consist in preparing
two long receptacles in such a way that one is the normal environment
of the animals in all respects and the other in all respects except for
one factor, as, for example, temperature. The temperature conditions
of the latter might be as follows: temperature at one end io° C, at the
other 35 C, with a gradient between. If then 100 animals are placed
in each of the receptacles, those placed in one end of the gradient will
soon show signs of stimulation and will move about until they come
near the center of the pan where the temperature is 2o°-25°. If, after
sufficient time has elapsed for the experimental animals to take up this
position, the control animals have remained equally distributed, the
experiment will show that the animals have responded to temperature
alone.

Certain general laws govern the reaction of animals to different
intensity of the same stimulus. Take, for example, temperature.
There is in most animals which have been subjected to experimentation
with temperature a range of several degrees within which the activities
of the animal proceed without marked stimulative features, as is sug-
gested by the experiment outlined above. Conditions within this
range of several degrees are called the optimum. As the temperature
is raised or lowered from such a condition, the animal is stimulated.
If the temperature is continuously raised, a point is reached at which
the animal dies. The temperature condition just before death occurs
is called the maximum (35). The lowering of temperature produces
comparable results.

2. EXPERIMENTAL STUDIES OF HABITAT SELECTION

Animals select their habitats, and distribution is the result of this
selection. To decide whether or not one factor can determine distri-
bution, experiments, of which the following is a typical example, have
been performed.

a) Methods of experimentation. — Do animals select their breeding-
places ? To answer this question, tiger-beetles were selected as material
and adults were placed in cages containing soil of several kinds. Each
kind was so arranged into steep and level parts, that about one square
foot of each type was exposed. The adults placed in the cage were

ACTIVITY AND DISTRIBUTION

30I

taken when the species was breeding (see p. 2 1 2) . The soil was kept very
moist up to the time the first ovipositor holes were made, because this
species lays only in moist soil. After this the wetting of the soil was
done very cautiously, so as not to wash the eggs from the ground in
steep parts. Accordingly, the holes were not obliterated from day to
day. The counts, however, are not accurate for the soil in which a large
number were made, because eggs are sometimes laid very close together
and adjoining holes destroyed. Some eggs are deposited in irregular
cracks and crevices where they are likely to be overlooked. The greatest
care was taken to discover every hole made in the soils in which larvae
do not occur in nature. Soils in the different lots were arranged in
different orders.

b) Results. — Table LXVIII shows the approximate number of holes
made in the clay and probably the actual number made in the other
soils, together with the number of larvae which appeared: 80 per cent
on the steep slope, 98 per cent in clay.

The count of holes includes some in the first stages of digging, mere
scratches on the ground, and others which had been excavated to the
usual depth with or without eggs being laid.

TABLE LXVIII (55)

Distribution of Ovipositor Holes and Larvae of C. purpurea limbalis under
Experimental Conditions
S = steep; L = level.

Clay

Clay, 9 Pts.
Humus, i Pt.

Forest
Humus

Humus, i Pt.
Sand, 9 Pts.

Clean
Sand

s

L

s

L

s

L

s

L

S

L

\Larvae

LotIl{P oles

[Larvae

LotIIl{P oles

[Larvae

9

21
12

17
24

s

I

7
10

1
1

O

c

c

c) Factors controlling habitat selection (55). — Pairs taken in coitus
were placed in cages containing sand only and level clay only. No
larvae appeared in either case. The experiment with the level clay
has not been repeated. Females placed in cages containing rough,
steep clay, deposited eggs. Eggs are also absent from dry soils, whether
steep or level.

302 ECOLOGY

Slope, kind of soil, and soil moisture are factors governing the
deficiency or absence of eggs. A deficiency or excess in any one of
these respects decreases the number of eggs laid, or causes them not to
be laid at all. The animals are in the condition for egg-laying for but a
short period.

d) Method of selection. — It has been determined by opening holes
that eggs are not laid in all, and in one case the first holes made by the
female were empty. This would tend to show that the female beetle
tries the soil before laying the eggs, but I have not been able in other
cases to determine whether the first holes contained eggs or not. To
determine this, it would be necessary to watch a female all of the time
during several days.

3. LAW OF TOLERATION (55)

Repeated experiments with several species have shown results
similar to those shown in Table LXVIII, and we have concluded that the
egg-laying place of the tiger-beetles is their true habitat. The tiger-
beetles which lay eggs in soil do so only when the surrounding tempera-
ture and light are both suitable, the soil moist and probably also warm.
The soil must satisfy the ovipositor (egg-laying organ) tests with respect
to several factors. Egg-laying, the positive reaction, is then probably
a response to several factors. Furthermore, after the eggs are laid, the
conditions favorable for egg-laying must continue for about two weeks
if the eggs are to hatch and the larvae reach the surface. The success
of reproduction depends upon the qualitative and quantitative com-
pleteness of the complex of conditions. This complete complex is called
the ecological optimum. The negative reaction, on the other hand, appears
to be different. The absence of eggs, the number of failures to lay, and
therefore the number of eggs laid in any situation, can be controlled by
qualitative or quantitative conditions with respect to any one of several
factors. The presence, absence, or number of eggs laid may be governed
by a single factor.

For example, all other conditions being optimum, moisture may
control the presence, absence, or number of eggs laid. If the moisture
be optimum, the maximum number of eggs will be laid. If it is too
great few or no eggs will be laid. This factor then controls according
as it is near the optimum, or near either the maximum or minimum
tolerated by the species. It is, however, not necessary that but a single
factor should deviate; the effect is similar or more pronounced if several
vary.

LAW OF TOLERATION 303

The success of a species, its numbers, sometimes its size, etc., are
determined largely by the degree of deviation of a single factor (or
factors) from the range of optimum of the species. It is obvious that
the cause of the fluctuation might be, for example, moisture due to
(climatic) deficiency in rainfall, or rapid run-off, due to steep slope.
The evidence for the application of the law of toleration to local distribu-
tion is good. Since the same factors are involved in the "geographic"
or more extensive distribution, there is no difficulty in the application
of the law to such distribution also, for, to assume that the law is not
applicable is to assume that animals distinguish between the causes
which lie back of the changes in physical factors by which they are affected.
The fact that, in so far as our observation can go at present, most animals
are found in similar conditions throughout their ranges is also good
evidence for the application of both the laws of minimum and toleration
to problems of geographic range. In fact, the law of minimum (see p. 68)
is but a special case of the law of toleration. Combinations of the factors
which fall under the law of minimum may be made, which make the law
of toleration apply quite generally. For example, food and excretory
products may be taken together as constituting a single factor. From
this point of view the law of toleration applies, the food acting on the
minimum side, excretory products on the maximum.

4. APPLICATION OF THE LAW OF TOLERATION TO DISTRIBUTION (55)

As has already been implied, the locality or region of optimum, or
the locality or region in which the animal is most nearly in physiological
equilibrium, is called the habitat (ecological optimum) when it refers
to ecological or local distribution, and the center of distribution when it
refers to extensive areas. The so-called centers of distribution are
often only areas in which conditions are optimum for a considerable
number of species. The distribution and number of individuals of any
species may be graphically represented as below:

Minimum Limit of t> ~r r\~i-. Maximum Limit of

Toleration

Absent

Decreasing

Range of Optimum

Habitat or center of distribution
Greatest abundance

Toleration

Decreasing

Absent

On account of the nature and distribution of climatic and vegetational
conditions, it follows that as we pass in one direction from a center, one
factor may fluctuate beyond the range of toleration of a species under
consideration; but as we pass in another direction the fluctuating
factor is very likely to be different.

304 ECOLOGY

a) Governing the limit of local and geographic range. — The geographic
or local range of any species is limited by the fluctuation of a single
factor (or factors) beyond the limit tolerated by that species. In non-
migratory species the limitations are with reference to the activity which
takes place within the narrowest limits (usually breeding). In migratory
species this activity limits the range during only a part of the life history.

b) Governing the distribution area and habitat area (55). — The dis-
tribution area of a species is the distribution of the complete environ-
mental complex in which it can live, as determined (1) by the activity
which takes place within the narrowest limits and the animal's power
of migration, and (2) by barriers in which some factor of the complex
fluctuates beyond the limits of toleration of the species in all periods of
its life history.

If these statements are borne out by further investigation it follows
that every study of animal behavior which is related to measured physical
factors or to natural environments is directly related to problems of dis-
tribution.

III. Agreement between Plants and Animals

In recent years the ecology of plants has received much attention
and the subject has made great progress. In animal ecology but little
progress has been made, and students (and teachers) have been inclined
to expect relations and conditions in animals parallel with those in plants.
Little progress has been made, largely because workers have not recog-
nized the important phenomena in animals as compared with plants.

I. ECOLOGICAL AGREEMENT OF INDIVIDUALS

Organisms may be divided on the basis of their ability to move
about, into sessile or fixed, and motile forms. All organisms are of course
capable of movement of some sort, even though it be only mechanical
movement dependent upon turgor. There are also all degrees of ability
to move from place to place. Some motile plants and animals move
about only very slowly, and the division of organisms into sessile and
motile is a somewhat artificial classification, as many forms are difficult
to place in either group. Some are sessile at one period of their lives
and motile at another. Comparable difficulty arises, however, in the
separation of plants from animals.

The animals with which we, as inland people, are most familiar,
are the highly motile forms, and the plants with which we are most
familiar are sessile forms. We are all also somewhat familiar with

AGREEMENT OF COMMUNITIES 305

numerous marine animals, such as polyps, sea plumes, etc., which are
sessile, like plants. Sessile animals are probably all aquatic. Logically,
ecology cannot be divided into plant and animal ecology, but it may be
divided into the ecology of sessile and motile organisms.

An appreciation of the likenesses and differences of sessile and
motile organisms is an important thing in ecology. The plant and the
animal groups contain both sessile and motile types together with types
intermediate between the two and thus taken as a whole plants and
animals are in agreement in the matter of response. However, since the
vast majority of animals with which we deal are motile, their activities
are evident because of their ability to move about. On the other hand
the majority of plants are sessile, and sessile individuals usually can
change the position of the whole or its parts only by growth. Changes
in the relation and character of parts are the results of the application of
stimuli to sessile plants. Movement is the chief result of the application
of stimuli to animals. Animal ecology has very much in common with
plant ecology. Diatoms, fiatworms, and many other marine animals
and plants meet the same conditions in the same or similar ways (72,
p. 121; 53a, p. 156; 536, p. 155). Sessile animals, such as reef-forming
corals, show growth form differences (193, 194, 195) under different
conditions, just as sessile plants do. Comparable plants and animals
show comparable responses. The physiological life history aspect of
plant ecology (52) is parallel with the same phenomenon in animals,
but the activities of motile animals correspond roughly to the growth
form phenomena in sessile plants (55, p. 593).

All the way through the study of ecology we look for behavior or
activity difference in motile organisms (chiefly animals), when con-
sidering the species of two different habitats, while, when making a
comparison of the sessile organisms (chiefly plants) of two habitats,
we look for differences in form and structure. To be sure an occasional
sessile plant can move some of its parts and likewise some motile animals
change color, size, or form with differing conditions during development,
but these are of secondary rather than primary importance and we must
look mainly to form changes as "plant response" and behavior, or activity
changes as "animal response."

2. AGREEMENT OF COMMUNITIES

Are physical conditions sometimes similar when vegetation and
landscape aspect are very different ? That they are is clearly suggested
when we compare the forest and the shrub-covered bluff where forest

306 ECOLOGY

animals occur. Plants grow from seeds only under a very limited range
of conditions. However, if trees are given a few years' growth under
favorable conditions they will be successful under a great range of con-
ditions. The great age to which trees often live and the slowness with
which they grow make it possible for conditions to change while the
trees still live on with changes only in leaf structure. It is to be expected
that the distribution of animals is correlated with the occurrence of
seedlings or of quick-growing plants or at least with leaf structure types
rather than strictly with species of trees. These facts suggest that
there are two types of cases in which physical conditions and forest
conditions are not in accord. In the first case atmospheric conditions
become favorable for forest animals before any woody plants have been
able to grow; in the second, woody plants remain after conditions have
become unfavorable for forest animals; both are due to lagging behind
of vegetation; both are very local and of minor significance.

The reasons for the wide distribution of some animals in the forest
stages which we have considered are no doubt various. For example
Zonitoides arbor eus (Table L, p. 252) is rare in the early stages and is
confined to the lower and moister localities. If Epeira domicilorum is a
species of stable physiological makeup we can offer no explanation for
its peculiar distribution (Table LVI, p. 257). A species may have its
critical period in the early spring when the leaves are off the trees and
the condition of the atmosphere similar in all stages (see Fig. 251, p. 248)
or may live at higher levels in the denser and older stages, and thus be
surrounded by similar atmospheric conditions, but we are not warranted
in assuming either of these causes here.

Another striking feature of the distribution of many beetles, bugs,
spiders, and Orthoptera is the fact that they are found in open woods,
edges of woods, on the vegetation of marshes, and over the water of small
ponds in which vegetation is growing. In this way many species are
found to occur in what at first appear to be very unlike situations.
Lygus pratensis, Triphleps insidiosus, and Euschistus variolarius,
which occur on the vegetation of the margins of swamps, of the
black-oak forest dunes, and on prairies and agricultural lands, may
serve as examples. Shull has pointed out similar facts as one of the
difficulties in the way of ecological classification of Orthoptera and
Thysanoptera. Such species as the bugs mentioned above are said to
occur "everywhere," although they are rarely found in moist woods or
in any situation in which they are not full""" exposed to the sun and
may always live in similar conditions.

AGREEMENT OF COMMUNITIES 307

Some investigators have questioned the importance of vegetation
to animals and we note here that the distributions of plant and animal
species are not always correlated. If one refers to species of plants
and species of animals then the vegetation very often is not correlated
with the distribution of the animals. If on the other hand one means
that the plants are controllers of physical conditions, then vegetation
can be said to be of very great importance.

Before discussing the problem of agreement between plant and
animal communities, it is necessary to state what is meant by agreement.
According to present developments of the science of ecology plant and
animal communities may be said to be in full agreement when the growth
form of each stratum of the plant community is correlated with the conditions
selected by the animals of that stratum. Questions of agreement are pri-
marily questions for experimental solution. Two types of disagreement
are to be expected. We may illustrate the first by a bog or marsh
community. Considering plants rooted in the soil we note that water
is secured from the soil by the roots and is lost through the leaves and
twigs. Accordingly since bog soil is unfavorable, due to the presence
of toxins or to other causes, plants growing in it do not secure water
easily even when the quantity of soil water is great. Such plants have
xerophytic structures (which tend to check the loss of water) developed far
beyond the requirements of the atmospheric conditions surrounding their
vegetative parts. It is improbable that the animals inhabiting a bog-
vegetation field stratum would select atmospheric conditions such as
produce equally xerophytic structures under favorable soil conditions.
We may therefore expect disagreement. The smaller plants such as
fungi, algae, etc., are related to the strata of soil and atmosphere exactly
as the smaller animals and as much disagreement is to be expected between
such plants and the rooted vegetation as between the rooted vegetation
and animals. It must also be noted that the xerophytic structures of
the plants of unfavorable soils may have important influence upon ecto-
phytic plants and animals and in part counteract the effect of favorable
atmospheric conditions.

The second type of disagreement is represented by cases in which
the vegetation lags behind. We have already noted that on the clay
bluff (pp. 209-17) conditions become favorable for inconspicuous plants
and forest animals as soon as the growth of the pioneer vegetation gives
shade to the soil. In other cases woody vegetation remains in situations
where the conditions have become unfavorable for it and the less con-
spicuous plants and some of the animals have disappeared. We may

308 ECOLOGY

expect lack of accord within and between plant and animal communities
under such conditions. In these cases, however, conditions are only
temporarily out of adjustment, due to rapid physiographic changes, and
we note from the data presented that plant and animal communities
are usually in agreement. The exceptions are often apparent only and
due to the emphasis of species instead of mores and growth form. From
this viewpoint and with such exceptions as are noted, plant and animal
communities are probably in agreement the world over.

IV. Relations of Communities

I. SUCCESSION — CAUSES

Succession is no doubt one of the most important and widespread
of the phenomena discovered by the ecologists up to the present time
(i 20, 197). Simply stated, it means that on a given fixed area organisms
succeed one another, because of changes in conditions. These changes
make impossible the continued existence of the forms present at any
given time; with the death or migration of such forms, others adapted to
the changed conditions occupy the area, whenever such adapted forms
are available. The changes referred to result from physical or bio-
logical causes, or combinations of the two. It is probable that the causes
of the changes are frequently complex combinations of various factors.

We have among the physical causes changes in climate and changes
in topography. All degradation of land is a cause of succession. Such
geological processes are well understood and treated in textbooks on
geology and physiography.

The biological causes of succession lie chiefly in the fact that organ-
isms frequently so affect their environments that neither they themselves
nor their offspring can continue to live at the point where they are now
living. Every organism adds certain poisonous substances to its sur-
roundings, and takes away certain substances needed by itself. It
frequently thus so changes conditions that its offspring cannot live and
grow to maturity in the same locality as the parents. However, by
these same processes it prepares the way for other organisms which can
live and grow in the conditions thus produced.

Obviously, those organisms whose decaying bodies and excretory
materials are not removed or distributed by their wanderings will
modify their environments most. Organisms which remain in one
place do nothing which tends to remove the results of their own existence,
and frequently modify their environments in manners detrimental to

CONVERGENCE 309

themselves. 1 On the land, plants are the dominant sessile forms, and
often profoundly modify the conditions in which they live, so that they
cannot succeed themselves. When will the process of succession stop ?
Obviously, it must cease when there are no available species to take the
places of those which have destroyed their own habitats. There are
species which are immune to their own products and the products of the
species which are associated with them. Obviously, when a condition
in which these species can live is reached, and they come to occupy the
place which is thus made ready for them, the formation which they
constitute can, so far as the plants are concerned, last indefinitely. This
is theoretically true of all climax or geographic formations, and has been
established for the beech and maple forest of eastern America.

2. MOTILE AND SESSILE ORGANISMS IN SUCCESSION

Motile Organisms Fixed Organisms

a) Motile organisms affect their own a) Sessile organisms modify their
environments by the destruction own environments largely through
of materials of abode and food growth of their own bodies, cutting
supply and the pollution of their off light, interfering with circula-
habitats by waste products (196, tion in surrounding medium and
114, and citations). accumulation of waste products

(195, 120).

b) The changes under (a) make the b) The same as for motile organisms
continued existence of the group (197).

in question impossible and pre-
pare the way for other differently
adapted (succession) forms.

c) Succession is a succession of c) Breeding and living places are not
breeding-places. contrasted as young stages usually

thrive only where adults can live.
Succession can take place only where forms adapted to the changed
conditions are available.

3. CONVERGENCE

The work of running water, for example, is in a measure convergent.
When a new body of land is uplifted, streams begin to work their way
into the new land mass and cut deep valleys. The formation of numer-
ous tributaries (92 and citations) isolates portions of the upland in the

1 In the sea (195) sessile forms are chiefly animals and animals are probably the
chief cause of succession there. Coral polyps cannot build upward indefinitely, as
they soon reach the surface and can no longer exist. By reaching the surface they
prepare the way for other forms.

3io

SAND RIDGE

Cottonwood
Gray pine
Black oak

White oak

ECOLOGY

CLAY BLUFF

Aspen
Cottonwood
Hop-Hornbeam
White oak

Red oak Red oak

Hickory Hickory

BEECH AND SUGAR MAPLE

Tulip Hickory

Basswood Red oak

White elm and
White ash

Swamp white oak
Buttonbush
Cattail and Bulrush

Water-lily and Water
Mill-foil

Bur oak

Basswood
Hawthorn

Slippery elm and
White elm

Chara

POND

River maple
Black willow
FLOOD-PLAIN

Diagram 8. — Showing the convergence of four types of habitat, to the beech
and maple forest. Read from the extremities toward center. (Prepared with the
assistance of Dr. Cowles and from his writings.)

CLIMATIC COMMUNITIES 311

form of hills. These hills are broken up into smaller hills by the smaller
tributaries, and the resulting hills into still smaller ones, until the upland
is all removed and the country reduced to a generally level condition
known as a peneplain. The process of peneplanation then tends to
fill all low lakes and ponds and drain all high ones. It works over all the
materials of the upland and lays them down as alluvial deposits, which
process tends to make the surface materials of a uniform nature. Asso-
ciated with this, and more or less independent of it, the process of plant
succession makes the conditions converging (Diagram 8) to a still greater
degree (13).

The principle of convergence, while not generally established, is
believed to be of wide application. It has been suggested for the tropical
forest of the Philippines by Whitford (198), for the coniferous forest
regions of North America by Adams and by Gleason, and for the arid
Southwest by Ruthven. Theoretically at least, in all the varied types of
land habitats of any large area, communities are tending toward some
one type which is primarily adjusted to the climate of the region when its
topography approaches base level. Such a climatic type of community
rapidly displaces the communities of all the varied kinds of soil of a
newly uplifted area which is only a few hundred feet above the sea. In
these situations the climatfc communities dominate sterile soil by process
of successional development extending over a few score or hundreds of
years.

V. General Relation of Communities of the Same
Climate (13)

In each climatic realm of the world there are relations between
communities of two sorts, (a) physiological relations, best defined as
physiological similarities, and (b) successional or evolutionary relations.
Diagram 9 shows both types of relations for the temperate American
forest border area. Single-pointed arrows show the directions of suc-
cession, double-pointed arrows show similarities of conditions and the
occurrence of several or many of the same species in considerable num-
bers in communities between which such arrows extend. Broken lines
indicate less definite relations than the solid lines. Starting with the
aquatic communities, we note that spring-fed and intermittent stream
communities converge with physiographic aging to small, permanent,
swift-stream communities, and permanent swift-stream communities
are succeeded by base-level stream communities. The characteristic

312

ECOLOGY

communities of small permanent streams and base-level streams are
indicated above. Taking up another line, we note that the large-lake
communities are succeeded by the small-lake communities. Rocky-
shore communities of the large-lake areas have features in common with
those of the rocky rapids of the stream. The sand, gravel, and vegeta-
tion communities of the base-level stream and the small lake have many
things in common, while the silt and humus bottom communities are
distinguishing features of the two. Communities of ponds originating

Sand

V--*

s, &

c,uc a *°'

S

Rock

L^PonH^j., r Climatic

^ ^Marsh-^, Molst Foresl Margin— ►Forest Margin.
Vegetation ~*\ ^^ or Thicket ♦ or Thicket

►■Base Level Stream ^f^4 \^ A

Silt bottom - ># o 4f a \ !

^ Thicket^-- --*» T ticker ; Rock

Spring Fed Brook — Vy^

^

Clay

Diagram q. — Showing some relations of the chief animal communities of the
forest-border region of Central North America. The word community or communi-
ties is to be understood as following all the words appearing in the diagram. For full
description see text.

by very rapid physiographic changes pass through a series of stages
comparable to those found in the different parts of the small lake. The
lake communities pass to the pond community stage or give rise to a
floating-bog marsh community which is displaced by a floating-bog
thicket community. Cowles states that this takes place in deep lakes,
while the shallow ones become ponds which give rise to marshes with
firm substrata. Such a marsh community may be displaced wholly
by a low prairie community, in part by a thicket forest margin com-
munity, or wholly by a thicket community which will be succeeded by

CORRESPONDENCE OF CLIMATIC COMMUNITIES 313

a forest community. In the savanna or prairie climate the marsh
margin thicket may become a climatic thicket or forest margin. In the
savanna or prairie climate the communities of all the various soils and
the low prairie community may converge to the prairie climate com-
munity, or to the forest community as is shown below for the forest
climate. In the forest climate and locally in the savanna climate the
communities of all the various soils pass through a thicket community
stage (T), related to a climatic forest. The thicket communities of all
the dry soils are related to the forest margin thicket community of the
savanna climate.

I. CORRESPONDENCE OF COMMUNITIES OF DIFFERENT PARTS OF
THE WORLD (55)

The botanists have abundant evidence for the correspondence of
the formations of similar climates (58a). The vegetation of different
parts of the world which have similar climates is similar and the plants
though usually belonging to different taxonomic groups are similar in
growth, form, and appearance. Correspondence and similarity of
vegetation is not limited to the climatic or extensive formations, but
applies also to strictly local situations wherever the physical conditions
are similar. On the animal side we have less trustworthy evidence of
similarity or correspondence. If the physiological similarity occurs in
the same community, due, as has just been stated, to selection of habitat
and modification of behavior, we conclude that it occurs in all communi-
ties occupying similar conditions and that similar situations in different
parts of the world have physiologically similar communities, and identical
situations approximately identical communities.

The direct evidences for the correspondence of formations in different
parts of the world are as follows: (a) the existence of identical or closely
corresponding species has long been known to naturalists (3, 199, 192);
(b) similarity of physiological life histories of many species is well known,
as, for example, corresponding species in the United States and Europe
or Japan, and a general concentration of breeding in the rainy season in
all arid climates, etc.; (c) certain animals in similar environments in
different parts of the worid appear from the accounts of naturalists to
behave alike with reference to the physical condition of different parts
of the day, year, and different weather. For example, it appears that
there is a close physiological and ecological similarity between certain
antelopes of the savannas of Africa and certain savanna kangaroos of
Australia (200). In other words certain kangaroos are ecologically and

314 ECOLOGY

physiologically similar to some antelopes. As has already been stated,
the zoologist is usually unduly impressed with specificities such as mode
of movement of limbs, body, etc. Now if my reader pictures an African
antelope running gracefully from a pack of Cape hunting dogs (102,
pp. 119-23), and an old-man-kangaroo leaping from a pack of dingoes
(202, pp. 41, 243), noting mainly the specific peculiarities of the movement
of limbs and body of the pursued in each case, he will be dwelling upon
specificities of little ecological significance and missing the point of view
of the ecologist altogether. These specificities of behavior are matters of
little ecological significance; it matters not if one animal progresses by
sommersaults so long as the two are in agreement in the matter of reac-
tions to physical factors as indicated by the manner of spending the day
(200), avoidance of forests, swamps, cold mountain tops, etc., entirely
available to them, and in the mode of meeting enemies as indicated by the
reaction to the approaching hunter or enemy.

a) Distribution of land communities represented in Central North
America. — The following climatic formations are represented at Chicago
and distributed as given below:

Temperate Deciduous Forest Formations: Forest with broad, thin leaves which

are shed in autumn; near Chicago, oak, hickory, beech, and maple (58a).

Distribution: Eastern North America, north to the Great Lakes;

Chili, north to 35 ; Europe, north of the Alps, and south of 6o°;

Japan and the vicinity of Okhotsk (58a).

Temperate Savanna Formations: Grasslands with scattered trees, or trees in

groves surrounded by thickets, and with dense forests along larger streams.

Near Chicago, the grassland is prairie and the trees chiefly oak and hickory.

Distribution: A narrow belt in North America surrounding the great

plains on the east, north, and west; Uruguay, South Australia,

South Africa, and Eastern Siberia.

Formations of Forests with Narrow Thick Leaves: Coniferous forest. Dense

evergreen forests with little undergrowth. Lies just to the north of

Chicago and was represented locally in the parts of Michigan shown on

Map I (frontispiece).

Distribution: North America north of the Great Lakes and Columbia
River extending southward into the mountains; Eurasia north
of 6o°, extending southward into the mountains.

The localities which are in agreement are indicated by distribution
of the different types of formation. It will be noted that the deciduous
forest animal formation with which we have dealt is found in several
parts of the world, this animal community being essentially duplicated in

ECOLOGY AND BIOLOGY 315

these differently located areas. This correspondence is probably much
more striking physiologically than in the matters of interrelation of
species because in some formations certain groups, as, for example,
antelopes in African steppes, are especially numerous, while in a
corresponding situation in South America they are very few.

As has already been suggested, correspondence is not limited to
the gross characters of extensive formations, but is equally true of
the more local communities. In matters of correspondence of species
there are often striking correspondences within the groups of formation
indicated above. For example, there is a striking correspondence in
behavior between the meerkats of the steppes of East Africa (3) and
the prairie dogs of our own steppe, both being grasslands but differ-
ing in climate. Considering a local formation, as that of the sandy
beaches of the sea and very large lakes, we note that along the New
England coast and around the shores of Lake Michigan the moist,
sandy beaches are inhabited by the larvae of the beach tiger-beetle
(Cicindela hirticollis) (Fig. 134, p. 179). Along the Gulf Coast at Galves-
ton, Texas, we find the larvae of C. saulcyi inhabiting almost identical
situations, holes of about the same depth, etc., while Dr. Horn (203)
describes a different larva in like situations and with like habits on the
coast of India.

Still, with all that has been said, matters of agreement of different
animal communities in different parts of the world are largely theoretical,
and while apparently logically well grounded, the general statement
must be treated with due caution and subjected to experimental test
as soon as possible. Such testing will involve careful experimental
study of the communities of two like environments under rigidly con-
trolled and carefully measured conditions.

VI. Relations of Ecology to Other Biological Subjects

The environmental processes which we are discussing are those in
which organisms have existed since their origin on earth. The stresses
and strains to which organisms have been subjected have been in the
same direction for long periods. Now that we have learned much
concerning organic response to environment, such as physiological
response, behavior response, and structural response, we note at once
that processes of adjustment and equilibration of living substance may
bear important relations, on the one hand to environmental processes,
and on the other to the physiological aspect of biological phenomena.

316 ECOLOGY

Ecological matters are then worthy of the attention of the student of
morphology, heredity, and evolution.

What is the significance in the fact that the white tiger-beetle
(Cicindela lepida) belongs to the first association in the development
of a forest community on sand, which we may say corresponds to a
family, and to the subterranean ground stratum (corresponding to genus)
and to the white tiger-beetle mores? Furthermore, that Cicindela
lecontei and the green tiger-beetle {Cicindela sexguttata) belong respec-
tively to different and older situations or associations ? We note that the
habitats in which the species occur are characterized by distinctly differ-
ent soils, moisture, amounts of shade and light. We note, furthermore,
that these animals are possessed of unusual powers of flight and
are able to select conditions suited to their physiological constitution.
Their mores characters are definite characters, which can be measured
in terms of reactions to measured complexes of physical and other
environmental factors. They are as clearly defined as any morphological
taxonomic characters and can be measured with the accuracy of any
physical phenomena.

Doubtless to the student of genetics or evolution, the question of
the origin of such characters and their fixation in heredity is a leading
question. At this point we know little or nothing. Since nearly all
species have definite habitat preferences and since many varieties differ
slightly from the related species form in the matter of habitat preference,
it is probable that origin of a slight change in habitat preference, mean-
ing a slight change in reaction to physical factors, a change in ecological
optimum, is usually an early correlative of the origin of new races.
Still the so-called taxonomic characters may remain apparently
unchanged, while marked changes in habitat preference and in reaction
to physical factors are being brought about in plastic animals (56).
On the other hand, the segregation in the pure lines and races accom-
plished in experimental breeding often appears to take place without
any regard to environment (204). These two facts, accepted as they
stand, are in full accord and we might conclude that there are no rela-
tions between primary ecological characters and taxonomic characters.
Such, however, can hardly be strictly true, but we cannot see what the
real relations may be. If our point of view is correct the ecological
characters of a race experimentally segregated, or experimentally pro-
duced, must in practice consist primarily of reaction to physical factors
or combinations of physical factors or to entire environmental complexes;
secondly of a definite rate of metabolism, time of appearance or the like;

ECOLOGY AND BIOLOGY 317

thirdly of specificity of behavior, and fourthly of structural characters
modifying behavior. Relatively fixed taxonomic integumentary charac-
ters have no bearing on ecological matters, not even according to the
broadest definitions of the subject. The characters which are not related
to the environment and which are of no ecological value are the ones
quite generally used in breeding work, specificity of behavior standing
second, and plastic structure third, primary ecological matters usually
receiving no adequate attention or only such attention as comes incidentally
with the handling of the material. The results consist of noted differences
in reaction to light of doubtful intensity and quality, or similar inaccu-
rately measured temperature differences, etc. The testing of primary
ecological characters can be easily conducted and will answer the question
before us.

With all of its imperfections and uncertainties, the ideas of phylogeny
which are presented in our phylogenetic system of taxonomy are an impor-
tant asset in zoological thinking from the point of view of structure and
development. The classification which ecologists are striving to build
up will serve a purpose in behavior, physiology, and ecology, analogous
in this respect to that served by the phylogenetic classification in morpho-
logical thought, but should be flexible rather than rigid and true to fact
rather than to schemes. Figuratively speaking, an ecological classifica-
tion cuts taxonomy vertically, showing many structural adaptations as
matters of stratum or over-adaptations (205) or lack of adjustment to
conditions (206, 206a). It also cuts it again horizontally, showing eco-
logical similarity in organisms structurally and phylogenetically diverse.
It therefore provides a new and different means of organization of data.

In this work we have sharply separated evolution and structure,
on the one hand, from physiology and behavior, on the other. Space,
clearness, and the condition of the subjects have forbidden that we
attempt to unite them here. While it may be expedient to continue in
this manner until our knowledge of physiology and behavior is commen-
surate with that of the other subjects, the following of such a course
indefinitely, with respect to either morphological or physiological aspects
of biology, cannot, if it be general, bring about the best development or
unification of biological science. Indeed, its present lack of unity is
traceable to such a course followed until recently by zoologists generally.

If our understanding of the data of physiological cytology be correct,
we may expect to find so-called structures of some sort within or among
the cells concerned in function, which stand for or are correlated with
each physiological state and physiological condition to which we have

318 ECOLOGY

referred. Our methods may not, at present, be sufficiently delicate to
detect such structure, or the processes which lie back of it, but we may,
it is believed, confidently expect the necessary methods for the detection
of such structures and processes, and especially their correlation with and
relation to the more permanent and more easily recognizable morpho-
logical conditions.

We classify the responses and changes in animals as evolution,
modification by the environment, behavior, and physiological response.
Are not all these, after all, but different expressions of the same or
similar processes? Future investigations must answer this question,
and it is around this question that the future of much that is known as
biology hinges.

VII. Relations of Ecology to Geography

Ecology is primarily the study of the mores of animals and animal
communities. It is fundamentally a branch of physiology — the physi-
ology of the relations of animals to their environments. While we may
study in the field and in the laboratory, both types of study are commonly
conducted with reference to natural environments. Natural environ-
ments are used as the basis for study, because when natural environments
are destroyed, animals which can live in the new conditions select some
one of several possibilities which approach the normal habitat. Habits
appear particularly variable under these conditions. Little can be
gained from the study of the relations of animals to man-made environ-
ments, except in cases where the species has long been living under
such conditions and has become fully adjusted to them.

Ecology being a subject or branch of physiology, and including
all of the sociological side of animal life, its relations to human geography
are particularly intimate. Indeed, geographers have been disappointed
with the data which zoology has furnished them, as these data are
almost exclusively data concerning the taxonomy and morphology of
animals. The parallelism between the geographic phenomena in animals
and the "relation of culture to environment" lies not in the color and
structural adaptations of animals, but in the behavior-characters of
animals which enable them to live under a given set of conditions, and
the behavior which those conditions produce (207, 208, 209).

While attempting to make comparisons between human society
and man on the one hand, and plants and animals on the other, geog-
raphers, sociologists, and psychologists — in so far as I have been able
to read their writings along this line — have compared structure in plants

ECOLOGY AND GEOGRAPHY 319

and animals with what is obviously not structure in man, namely, his
culture and mental makeup. Waxwieler (210) compares human society
with the whole animal kingdom, as constituting another society. McGee
(211) takes a similar position. In discussing the relation of culture to
environment he says :

When the law of biotic development is extended to mankind, it appears
to fail; for the men of the desert and shore land, mountain and plain, arctic
and tropic, are ceaselessly occupied in strife against environmental conditions
which transform their subhuman associates; yet men remain essentially
unchanged, some taller, some stouter, some swifter of foot, some longer of life
than others, yet all essentially Homo sapiens in every characteristic.

More careful examination indicates that the failure of the law when
extended to man is apparent only. The desert nomads retain certain common
physical characteristics, but develop arts of obtaining water and food and these
arts are adjusted to the local environment

He continues with the citation of other cases. Such adjustment of
arts (212) is comparable to the adjustment of animals with regard to
food, nest-building, materials used in nest-building, and other features
of ecology and behavior. Finally, animal ecology offers the material
and methods with which many ideas of geography may be experimentally
verified (213, 214).

APPENDIX

Methods of Study

Methods used in the study of environment, while not new, involve
the methods of several sciences. To determine the gross features, the
methods of dynamic and historic geology and physiography, or of plant
ecology, must be applied. For further analysis the methods of meteor-
ology and special methods for measuring the environment physically
and chemically must be employed, where other sciences have given us no
data and method (see Clements). These consist of methods of studying
the rate of evaporation, water content of the soil, and the application
of meteorological methods to climatic details. The special chemical
methods, aside from chemical methods of the study of the soil, consist
of detection of the presence of excretory products in the soil or water.
The best discussion of special methods is given in the references (35a, 43,
6o> 74, 76, 77, HI, n8, 121, 124, 125, 129, 130, 131).

METHODS OF STUDYING ANIMALS IN THE FIELD AND LABORATORY

a) Observation. — One important thing in ecological study is simply to
sit quietly and watch animals, and record what they do. This requires
much time, and the best observers often sit for hours before making the
desired observations, but the reward is always adequate. Some good
ecological knowledge has thus been acquired. One difficulty is encoun-
tered in this work. When the observer is watching one animal whose
actions are not of especial interest at that moment another animal often
suddenly appears and does something which seems of importance or
which is of especial interest. The observer's attention is diverted from
its original object of observation. " Which shall I continue to watch ?"
is often asked by the student. No definite rules can be laid down. In
general it is probably better to follow the original object. The answer
depends entirely upon the relative ease with which the two animals before
the worker can be observed. The beginner cannot answer this question
and only experience can decide which should be followed.

b) Experimentation. — Investigation in ecology requires, in prepara-
tion, long training in both the biological and physical sciences. Persons
not possessing such training cannot hope to make important contributions
to the science. Ecology is a field often requiring very complicated
experimental methods. Animal behavior and some aspects of physiology

321

322 ANIMAL COMMUNITIES

are fundamental in ecology. We can sketch out here only such methods
as are modifications of the usual method of these branches of biological
science in such a way as to be intelligible to those somewhat familiar
with such laboratory methods.

(a) Experiments in the field are of prime importance in ecological
work. Here smaller animals can be secured in numbers and subjected to
experimental conditions before their physiological state has been modi-
fied by bad treatment. Any student competent to undertake ecological
investigation will find no difficulty in devising apparatus which can
be carried into the field and which will enable him to do work of a
high degree of scientific accuracy. Each experiment should be accom-
panied by a control. That is, the same number of animals should be
put under the same conditions as in the experiment, except for the one
factor which is to be varied. For example, in an experiment designed
to determine the reaction of animals to light, the control should be
either equally lighted or entirely dark (more easily accomplished), and
the experiment which is exactly the same except that the light ranges
from darkness to bright sunlight.

The apparatus which we have just begun to develop for this purpose
is still in need of much perfecting. Thus far it consists of granite-iron
and galvanized-iron containers about 13 in. long, 3 in. deep, and 4 in.
wide. These are provided with galvanized-iron covers, somewhat larger,
and a little deeper. One of these is provided at one end, with an adjust-
able slide which may be used to open a slit to admit light when desired.
In connection with this slit a mirror is provided with which the sunlight
may be projected into the pan as nearly vertically as possible. The rays
are allowed to pass through a water screen to cut out the heat. For work
with temperature the same receptacles have been used and temperature
differences secured by placing one end of the experimental tank in contact
with hot soil and the other with cold soil. Land animals are confined in
tubes 11 in. long by if in. in diameter with round bottom and close-
fitting cap, shaped like the bottom. Reactions to gravitation have been
tested with the use of wire cylinders for land animals, and glass cylinders
lined with screen for aquatic animals. Black covers are used to exclude
light in various ways as a check. For the study of reactions to current
two long galvanized boxes (24X5X4 in.) have been used, one having
screen ends and the other tight ends. They are placed in the stream
side by side, one serving as an experiment, the other as a control. Large
tin pans have been used in connection with the long boxes, the water in
the experiment being stirred so as to produce a circular current, while the

METHODS OF STUDY 323

control is left undisturbed. The study of reactions to contact has been
carried on by the use of pans described in connection with light and tem-
perature and with the use of mica chips, leaves, etc.

In all experiments the containers are divided into several divisions
and the number of animals noted in each division counted at each
reading. About ten readings are taken, the number being determined
by the number of animals used, w T hich is determined by the number that
can be observed before they can move any considerable distance. This
is a function of the speed of movement, which also determines the fre-
quency of reading. Readings should be taken at such intervals as to
enable the animals to completely adjust their positions with reference
to the conditions in the interim.

The most effective method of study is that of mixing animals of differ-
ent habitats; this removes the necessity of accurate measurement for
rough comparison. The degree of accuracy of such experiments is
determined almost entirely by the ingenuity and care exercised by the
experimentor. Accuracy of measurement can be acquired, but in the
case of some factors, such as light, with some difficulty. Such accuracy
should, however, be the constant aim of the worker.

While a high degree of accuracy may be attained in the field in the
case of some factors and reactions, it is, in other cases, necessary to
perform experiments in the laboratory also. As a rule all experiments
should be performed in both field and laboratory.

(b) To determine the most important activities: The first step in
field observation is the continuous watching of animals throughout a
number of life cycles. Experimentation is almost always necessary also.
It is only under unusually favorable conditions that the relative impor-
tance of the various periods of the life history of an animal can be
ascertained without experimentation. On the other hand, experimen-
tation must be correlated with field observation. Simple experimenta-
tion on the behavior of animals in the laboratory does not illuminate
this matter to any appreciable extent.

To determine the habitat preference of animals, they should be placed
in cages, in which they find several different sets of natural conditions,
and the selection made by the animal noted.

METHODS OF TAKING A CENSUS

Species are of importance because each usually has a physiological
makeup and habitat preference differing from other species. To make a
census of the animals present in a given habitat it is necessary to visit

324 ANIMAL COMMUNITIES

the place at various times of day and night and at various times of the
year, to overturn and open all loose objects. It is necessary therefore to
collect animals which have been observed in nature in such a manner
that the correct names can be applied later. It is customary to assign
numbers to the animals. The method commonly used is as follows:

Loose sheets of ruled paper are filled in with the locality, date,
weather, etc., carbon copies usually being made as a matter of safety and
convenience. Next, an animal, say a spider, is observed as fully as time
permits, the observations are recorded, and the specimen, if small, is
placed in a 4-drachm homeopathic vial containing alcohol. The notes
are written in abbreviated form on a slip, and the same number assigned
to the notes and to the slip which is put in the bottle. Animals too large
to put into bottles are prepared in the same way by tying a tag to each.
In due time the bottle is sent to a specialist who assigns the name, which
is recorded in a blank space on the note sheet. A new sheet is filled
out for each different habitat, and later all the sheets relating to one
kind of a situation can be brought together.

Nearly all animals can be sufficiently well preserved to permit
identification by specialists, in the following manner:

a) Vertebrates, in 10 per cent formalin, the abdomen opened to permit the fluid

to enter.

b) Crustaceans, most insects, spiders, worms, and lower forms by dropping into

80 per cent alcohol.

c) Insect larvae and pupae must be subjected to high temperature, 8o° C, or

they will turn black. Vials or bottles containing them with corks removed
should be set in a pan of hot water for 20 minutes immediately after
returning from the field.

d) Flies must be killed by poison fumes, pinned in the field, and the pins set in

suitable boxes.

e) Moths and butterflies must be killed by fumes and pinned; the partial

spreading of one pair of wings will suffice and save much time.

BIBLIOGRAPHY

[References are numbered in the order of first citation in the text, beginning with

Chapter I.]

Chapter I

i. Ritter, W. E. The Marine Biological Station of San Diego. Circu-
lated by the Station, La Jolla, Cal. 1910.

2. Brehm, A. E. From North Pole to Equator. London. (Tr. by Thom-
son.) 1896.

3. Roosevelt, T. African Game Trails. Scribners. 1909-10.

4. Haddon, A. C. The Saving of Vanishing Data. Pop. Sci. Mon.,
LXII, 222-29, 1903.

5. Webb, Sidney. The Diminution and Disappearance of the Southeast
Fauna and Flora. Southeast Nat., VIII, 48. 1903.

5a. Forbes, S. A. The Native Animal Resources of the State. A Sym-
posium on Conservation. Tr. 111. Ac. Sci., Vol. V. 191 2.

6. Shelford, V. E. Ecological Succession. Ill, A Reconnaissance of Its
Causes in Ponds with Particular Reference to Fish. Biological Bull.,
XXII, No. 1, and citations. 191 1.

7. Ruthven, A. G. Variation and Genetic Relationships of the Garter
Snakes. U.S. Nat. Mus., Bull. 61. 1908.

8. Beal, F. E. L. The Relations between Birds and Insects. Yearbook of
Dept. of Agri. for 1908, pp. 343-50.

9. Surface, H. A. Serpents of Pennsylvania. Penn. State Dept. Agri.,
Div. Z06L, IV. Nos. 4 and 5. 1906.

ga. Surface, H. A. Lizards of Pennsylvania. Ibid., V, No. 8. 1908.

10. Kirkland, A. H. The Usefulness of the American Toad. U.S. D. of
Agri., Farmers' Bull. 196. 1905.

11. Forbes, S. A. The Food Relations of the Carabidae and Coccinellidae.
Bull. 111. State Lab. Nat. Hist., Bull. No. 6, pp. 33-64. 1883.

12. Warming, E. Ecology of Plants. An Introduction to the Study of
Plant Communities, and citations. Oxford. (Tr. by Percy Groom.)
1909.

13. Shelford, V. E. Ecological Succession. V, Aspects of Physiological
Classification. Biol. Bull., Vol. XXIII, 331-70. 191 2.

14. Kirkland, Joseph. Chicago Massacre of 181 2. Chicago. 1893.

15. Blanchard, Rufus. Discovery and Conquests of the Northwest.
Chicago. 1898-1900.

16. Report of the Commissioner of Indian Affairs. 1890.

17. Sparks, Jared. Life of Robert Cavalier de LaSalle. Boston. 1848.

325

326 ANIMAL COMMUNITIES

18. Parkman, F. LaSalle and the Discovery of the Great West. Boston.
1872.

19. Mason, E. G. Early Chicago and Illinois. Chicago Hist. Soc. Coll.
No. IV. Chicago. 1890.

20. Ellsworth, H. L. Illinois in 1837. Philadelphia. 1837.
20a. Reynolds, John. My Own Times. Chicago. 1855.

21. Wood, F. E. A Study of the Mammals of Champaign County, 111.
Bull. 111. State Lab. Nat. Hist., VIII, Art. V, 501-613. 1910.

22. Kennicott, R. Catalogue of Animals Observed in Cook County, 111.
Trans. 111. Agri. Soc. I, 557-95- 1855.

23. Jones, A. Illinois and the West. Boston. 1838.

24. Marsh, M. C. The Effects of Some Industrial Wastes on Fishes. U.S.
Geol. Surv., Water Supply and Irrigation Paper No. 912 (The Potomac
River Basin), pp. 337-48. 1907.

25. Nichols, W. R. Water Supply. New York. 1894.

26. Forbes, S. A. Some Interactions of Organisms. Bull. 111. State Lab.
Nat. Hist., I, 3-18. 1880.

27. Park, W. H. Pathogenic Microorganisms Including Bacteria and
Protozoa. Philadelphia. 1905.

27a. McFarland, Jos. The Relation of Insects to the Spread of Disease.
Medicine, January, 1902.

28. Hortag, M., and others. Cambridge Natural History. Vol.1. London.
1906.

29. Braun, Max. Animal Parasites of Man. New York. 1906.

30. Darwin, Charles. Vegetable Mould and Earthworms. London. 1892.

31. Kunz, G. F. On Pearls and the Utilization and Application of the
Shells in Which They Are Found. Bull. U.S.F.C, 1893, pp. 439-57.

1897.

32. Stevenson, C. H. Aquatic Products in Arts and Industries. Rep.
U.S.F.C, p. 177. 1902.

33. Kingsley, J. S. (ed.). Riverside Natural History. II. 1884.

34. Sharp, D. Cambridge Natural History. Vol. VI. London. 1899.

Chapter II

35. Verworn, Max. General Physiology. London. (Tr. by F. S. Lee.)
1899.

35a. Adams, Charles C. Guide to the Study of Animal Ecology. New
York. 1913.

36. Parker, T. J., and Haswell, W. A. A Text-book of Zoology. Vol. II.
London. 1897.

37. Child, C. M. Studies on Regulation, II. Jour. Exp. Zool., I, 95-133.
1904.

37a. Child, C. M. Regulatory Processes in Organisms. Jour. Morph.,
XXII, 171-222. 1911.

BIBLIOGRAPHY 327

38. Osborn, H. F. From the Greeks to Darwin. New York. 1894.

39. Cope, E. D. The Primary Factors of Organic Evolution. Chicago.
1896.

40. Hancock, J. L. Nature Sketches in Temperate America. Chicago.
1911.

41. Eigenmann, C. Adaptation. Fifty Years of Darwinism: Modern
Aspects of Evolution. New York. 1909.

42. Standfuss, M. On the Causes of Variation and Aberration in the Imago
State of Butterflies. (Tr. by F. A. Dixey.) Entomologist, XXVIII,
69-76, 102-14, 142-50. 1895.

43. Hill, L., Moore, B., Macleod, J. J. R., Pembrey, M. S., and Beddard,
A. P. Recent Advances in Physiology and Biochemistry. London.
1908.

44. Jennings, H. S. Behavior of the Lower Organisms. Macmillan. Bib-
liography. 1906.

45. Mast, S. O. Light and the Behavior of Organisms. New York. 191 1.

46. Riddle, O. The Genesis of Fault Bars in Feathers. Biol. Bull, XIV,
328-70. 1908.

47. Johnstone, James. Conditions of Life in the Sea. Cambridge. 1908.

48. Merriam, C. H. Results of a Biological Survey of the San Francisco
Mountain Region and the Desert of the Little Colorado, Arizona. U.S.
Dept. of Agri., N.A. Fauna, No. 3. 1890.

49. Herrick, F. H. The Home Life of Wild Birds. A New Method of
the Study of the Photography of Birds. New York. 1902.

50. Reighard, Jacob. Methods of Studying the Habits of Fishes, with an
Account of the Breeding Habits of the Horned Dace. Bull. Bur. Fish,
XXVIII, 1112-36. 1910.

51. Semper, K. Animal Life. New York. 1881.

52. Ganong, W. F. Organization of the Ecological Investigation of the
Physiological Life Histories of Plants. Bot. Gaz.,XLIII, 341-44. 1907.

53. Allee, W. C. An Experimental Analysis of the Relation between
Physiological States and Rheotaxis in Isopoda. Jour. Exp. Z06L,
XIII, 269-344. 191 2.

53a. Bohn, G. Naissance de l'intelligence. Paris (Bibliotheque de philoso-
phic scientifique) . 19 10.

53&. Holmes, S. J. Evolution of Animal Intelligence. New York. 191 1.

53c. Abbot, C. C. Notes on Fresh-Water Fishes of New Jersey. Am. Nat.,
IV, 99-117. 1870.

54. Wheeler, W. M. Ants, Their Structure, Development, and Behavior.
New York. 19 10.

55. Shelford, V. E. Physiological Animal Geography. Jour, of Morph.
(Whitman Volume), XXII, 551-618, and citations. 191 1.

56. Allee, W. C. Seasonal Succession in Old Forest Ponds. Trans. 111.
Ac. Sci., IV, 126-31. 1911.

328 ANIMAL COMMUNITIES

57. Salisbury, R. D. Physiography. Henry Holt, New York. 1907.

58. Cowles, H. C. The Plant Societies of Chicago and Vicinity. Bull. II.
Geog. Soc. Chicago. 1901. Also Bot. Gaz., XXXI, 73-108, 145-82.

58a. Schimper, A. F. W. Plant Geography upon a Physiological Basis.
Oxford. (Tr. by W. R. Fisher.) 1903.

Chapter III

59. Leverett, F. Illinois Glacial Lobe. U.S. Geol. Surv. Monograph, 38.
1899. Maps: p. 420, Chicago and vicinity; p. 340, Southwestern
Michigan and Northern Indiana; p. 284, Fox River region.

60. Salisbury, R. D., and Alden, W. C. The Geography of Chicago and
Environs. Bull. I. Geog. Soc. Chicago. 1899.

61. Alden, W. C. Chicago Folio; No. 81, Geological Atlas of the United
States, U.S. Geol. Surv., Maps. 1901.

62. Atwood, W. W., and Goldthwait, J. W. The Physiography of the
Evanston-Waukegan Region. Bull. 7. 111. Geol. Surv. 1908.

63. Goldthwait, J. W. Abandoned Shorelines of Eastern Wisconsin.
Wisconsin Geol. and Nat. Hist. Surv., Bull. No. 17. Sc. Ser. 5. 1907.

64. Goldthwait, J. W. Physical Features of the DesPlaines Valley. 111.
Geol. Surv., Bull. 11. 1909.

65. Lane, A. C. Surface Geology of Michigan. Rep. Geol. Surv. Mich,
pp. 98-143. 1907.

66. Chamberlin, T. C, and Salisbury, R. D. Geology, III. Henry Holt,
New York. 1907.

67. Adams, C. C. Postglacial Dispersal of North American Biota. Biol.
Bull., IX, 53-7i- 1905.

68. The Climatology of the United States. U.S. Dept. Agri., Weather
Bur., Bull. Q. 1906.

69. Transeau, E. N. The Relation of Plant Societies to Evaporation.
Bot. Gaz., XLV, 217-31. 1908.

70. . Forest Centers of Eastern America. Am. Nat., XXXIX,

No. 468, pp. 875-88. 1905.

Chapter IV

71. Marsh, M. C. Notes on the Dissolved Content of Water in Its Effect
on Fishes. Bull. U.S.F.C., 1908. International Fish Congress. 1910.

72. Loeb, J. Dynamics of Living Matter. New York.

73. Shelford, V. E., and Allee, W. C. The Reaction of Fishes to Gradients
of Dissolved Atmospheric Gases. Jour. Exp. Zool., XIV, 207-66.

1913-

74. Birge, E. A., and Juday, C. The Inland Lakes of Wisconsin; the
Dissolved Gases of the Water and Their Biological Significance. Wis.
Geol. and Nat. Hist. Surv., Bull. No. 22., Sc. Ser. 7. 191 1.

BIBLIOGRAPHY 329

75. Ward, H. B. Biological Examination of Lake Michigan in the Tra-
verse Bay Region. Bull. Mich. Fish. Comm., No. 6. With appendices
by Jennings, Walker, Woodworth, and Kofoid. 1897.

76. Forel, F. A. Le Leman, monographie limnologique. In three volumes.
Lausanne. 1892-1904.

77. Kofoid, C, A. The Plankton of the Illinois River. Part I. Quantita-
tive Investigations and General Results. Bull. 111. St. Lab. Nat. Hist.,
VI, 95-629. 1903.

78. Marsh, C. D. The Plankton of Lake Winnebago and Green Lake.
Wis. Geol. and Nat. Hist. Surv., Bull. No. 12, Sc. Ser. 3. 1903.

79. Forbes, S. A., and Richardson, R. E. The Fishes of Illinois. Nat.
Hist. Surv. of 111., Vol. III. (State Lab. Nat. Hist.) 1908.

Chapter V

80. Smith, S. I. Sketch of the Invertebrate Fauna of Lake Superior. Rept.
U.S.F.C., 1872-73, pp. 690-707. 1874.

81. Milner, J. W. The Fisheries of the Great Lakes. Rep. U.S.F.C.,
1872-73, pp. 1-75. 1874.

82. Stimpson, W. Notes on the Deep Water Fauna of Lake Michigan.
Am. Nat., IV, 403. 1870.

82a. Hoy, P. R. (On Dredging in Lake Michigan.) Trans. Wis. Acad., I,
100. 1872.

83. Adams, Charles C, and others. An Ecological Survey of Isle Royale,
Lake Superior, 1908.

1. Adams, Charles C. General, pp. 1-57; Birds, pp. 121-54;
Beetles, pp. 157-203; Mammals, pp. 389-96.

2. Gleason, H. A. Ecological Relation of the Invertebrate Fauna,

P- 57-

3. Wolcott, A. B. Supplementary List of Beetles, p. 204.

4. Holt, W. P. Notes on Vegetation, p. 217.

5. Walker, Bryant. List of Mollusca, p. 281.

6. Morse, A. P. Report on Orthoptera, p. 299.

7. Needham, J. G. Neuropteroid Insects, p. 305.

8. Hine, J. S. Diptera, p. 308.

9. Titus, E. S. Hymenoptera, p. 317.
10. Wheeler, W. M. Ants, p. 325.

n. Ruthven, A. G. Cold-blooded Vertebrates, p. 329.
12. Peet, Max, M. Birds, pp. 97 and 337.

84. Meek, S. E., and Hildebrand, S. F. Synoptic List of the Fishes Known
to Occur within Fifty Miles of Chicago. Field Mus. Nat. Hist., Pub.
142. Zool. Ser. 7, No. 9. 1910.

85. Forbes, S. A. The Lake as a Microcosm. Bull. Peoria Sci. Assoc,
1887.

330 ANIMAL COMMUNITIES

86. Snow, Julia W. The Plankton Algae of Lake Erie. Bull. U.S.F.C.,
XXII, 371. 1902.

87. Jennings, H. S. The Rotatoria of the United States. Bull. U.S.F.C.,
XX, 67-104. 1900.

88. . On the Protozoa of Lake Erie. Ibid., XIX, 105. 1899.

89. Forbes, S. A. Some Entomostraca of Lake Michigan and Adjacent
Waters. Am. Nat., XVI, 640. 1882.

90. Clark, F. N. A Plan for Promoting the White Fish Production of the
Great Lakes. Bull. Bur. Fish., XXVIII, 637-43. 1910.

91. Baker, F. C. The Mollusca of the Chicago Area. Bull. Ill, Chicago
Acad. Sci. In 2 parts. 1898-1902.

910. Moore, J. P. Classification of the Leeches of Minnesota. Geol. and
Nat. Hist. Surv., Zool. Series No. 5, pp. 67-128. 191 2.

Chapter VI

92. Shelford, V. E. Ecological Succession. I, Stream Fishes and the
Method of Physiographic Analysis. Biol. Bull., XXI, 9-25. 191 1.

93. Smith, B. G. The Spawning Habits of Chrosomus erythrogaster.
Biol. Bull., XV, 9-18. 1908.

94. Lyon, E. P. On Rheotropism. I, Rheotropism in Fishes. Am. Jour.
Phys., XII, 149-61. 1904.

95. Needham, J. G., and others. Aquatic Insects in the Adirondacks. N.Y.
State Mus., Bull. 47. 1901.

96. Aquatic Insects in New York. N.Y. State Mus., Bull. Ento-
mology, 18. 1903.

97. Reeves, C. D. The Breeding Habits of the Rainbow Darter. Biol.
Bull., XIV, 35. 1907.

98. Needham, J. G., and others. May Flies and Midges. N.Y. State Mus.,
Bull. Entomology, 23. 1905.

99. Lefevre, George, and Curtis, W. C. Reproduction and Parasitism in
the Unionidae. Jour. Exp. Zool., IX, 79-115. 1910.

99a. Isely, F. B. Preliminary Note on the Ecology and Juvenile Life of the

Unionidae. Biol. Bull., XX, 77-80. 191 1.
996. Kingsly, J. S., Editor. Riverside Natural History, Vol. V. Mammals.

1888.
99c. Sherman, J. D. Some Habits of the Dytiscidae. Jour. N.Y. Ent.

Soc, XXI, 43-54-

100. Baker, F. C. The Ecology of Skokie Marsh with Particular Reference
to Mullusca. Bull. 111. State Lab. Nat. Hist., VIII, 441-97. 1910.

101. Ortmann, A. E. The Crawfishes of the State of Pennsylvania. Mem.
Cam. Mus. Pittsburgh, II, 343-523. 1907.

101a. Pearse, A. S. The Crawfishes of Michigan. Mich. Geol. and Biol.
Surv. Pub. Biol. Series No. 1, pp. 9-22. 1910.

BIBLIOGRAPHY 331

102. Weckel, A. L. Freshwater Amphipods of North America. Proc. U.S.
Nat. Mus., 1907, pp. 25-58.

103. Adams, Charles C. Baseleveling and Its Faunal Significance. Am.
Nat., XXXV, 839-52. 1901.

Chapter VII

104. Juday, Chauncey. Diurnal Movement of Plankton Crustacea. Tr.
Wis. Acad. Sci. Arts and Letters, XIV, 524-68. 1904.

105. Hankinson, T. L. Walnut Lake. Biol. Surv. of Michigan (Lansing).
Rep. Geol. Surv., 1907, pp. 157-271.

106. Gill, T. Parental Care among Freshwater Fishes. Smithsonian
Report for 1905, pp. 403-531. 1907.

107. Newman, H. H. The Habits of Certain Tortoises. Jour. Comp. Neur.,
XVI, 126. 1906.

108. Butler, A. W. Birds of Indiana. Rep. Ind. Dept. Geol. and Nat.
Resources, XX, p. 515. 1897.

109. McGillivray, A. D. Aquatic Chrysomelidae. N.Y. State Mus. Bull.,
LXVIII, pp. 288-312. 1903.

no. Juday, C, and Wagner, George. Dissolved Oxygen as a Factor in the
Distribution of Fishes. Wis. Acad. Sci. Arts and Letters, XVI, Part I.
1908.

in. Juday, C. Some Aquatic Invertebrates That Live under Anaerobic
Conditions. Ibid. 1908.

Chapter VIII

112. Shelf ord, V. E. Ecological Succession. II, Pond Fishes. Biol. Bull.,
XXI, 127-51. 1911.

113. Titcomb, J. W. Aquatic Plants in Pond Culture. Rep. U.S. Bur. Fish.
1908.

114. Colton, H. S. Some Effects of Environment on Growth of Lymnaea
Columella Say. Proc. Ac. Nat. Sci., Philadelphia, pp. 410-48. 1908.

114a. Dachnowski, A. The Toxic Properties of Bog Water and Bog Soil.
Bot. Gaz., XLVI, 130. 1908.

Chapter IX

115. Shelf ord, V. E. Ecological Succession. IV, Vegetation and the Control
of Land Animal Communities. Biol. Bull., XXIII, No. 2, pp. 5-99.
1912.

116. Van Hise, C. R. A Treatise on Metamorphism. U.S.G.S. Monograph,
XLVII. 1904.

117. Briggs, L. J., and McLane, J. W. The Moisture Equivalents of Soils.
Bull. 45, Bureau of Soils, U.S. Dept. Agri. 1907.

332 ANIMAL COMMUNITIES

118. Briggs, L. J., and Shantz, H. L. The Wilting Coefficients for Different
Plants and Their Indirect Determination. Bull. 230, Bureau of Plant
Industry, U.S. Dept. Agri. 191 2.

119. Fuller, G. D. Soil Moisture in the Cottonwood Dune Association of
Lake Michigan. Bot. Gaz., LIII, 512-14. 1912.

uga. McNutt, W., and Fuller, G. D. The Range of Evaporation and Soil
Moisture in the Oak-Hickory Forest Association of Illinois. Trans. 111.
Acad. Sci. 191 2.

120. Cowles, H. C. The Causes of Vegetational Cycles. Bot. Gaz., XLI,
161-83. Also Ann. Ass. Am. Geog., Vol. I. 191 1.

121. Schreiner, O., and Reed, H. S. Some Factors Influencing Soil Fertility.
U.S. Dept. Agri., Bull. Bur. Soils, 40. 1907.

122. Transeau, E. N. The Bogs and Bog Flora of the Huron River Valley.
Bot. Gaz., XL, 351-428. 1906.

123. Congdon, E. D. Recent Studies upon the Locomotor Responses of
Animals to White Light. Jour. Comp. Neur. and Psych., XVIII,
309-28. 1908.

124. Zon, R., and Graves, H. S. Light in Relation to Tree Growth. U.S.
Dept. Agri., Forest Service, Bull. 92. 191 1.

125. Hann, J. Hand Book of Climatology. Part I. (Tr. by R. de C.
W T ard.) New York. 1903.

126. Cohnheim, O. Physiologie des Alpinismus II. Ergebnisse der Physi-
ologic, Bd. 12. 1912.

127. Huntington, E. The Effect of Barometric Variation upon Mental
Activity. Preliminary Program 8th Ann. Meeting of the Ass. Am.
Geographers. 191 1. See Annals of the same society.

128. Walker, A. C. Atmospheric Moisture as a Factor in Distribution. S.E.
Nat., VIII, 43-47. 1903-

129. Yapp, R. H. Stratification of the Vegetation of a Marsh and Its Rela-
tion to Evaporation and Temperature. Ann. Bot., XXIII, 275-319.
1909.

130. Livingston, B. E. The Relation of Desert Plants to Soil Moisture and
to Evaporation. Carnegie Inst, of Wash., Publication 50. 1906.

130a. Evaporation and Plant Habitats. Plant World, XI, 1-10. 1908.
130&. A Rain-Correcting Atmometer for Ecological Instrumentation. Plant

World, XIII, 79-82. 1910.
130c. Operation of the Porous Cup Atmometer. Plant World, XIII, 111-19.

1910.

131. Fuller, G. D. Evaporation and Plant Succession. Bot. Gaz., XiVII,
195-208. 191 1.

131a. . Evaporation and Stratification of Vegetation. Bot. Gaz.,

LIV, 424-26. 1912.
131&. Fuller, G. D., and others. The Stratification of Atmospheric Humidity

in the Forest. Trans. 111. Acad. Sci., VI.

BIBLIOGRAPHY 333

132. Greeley, A. W. On the Analogy between the Effect of Loss of Water
and Lowering of Temperature. Am. Jour. Phys., VI, No. 2. 1901.

133. Bachmetjew, P. Ueber die Temperature der Insekten nach Beobach-
tung in Bulgarien. Zeit. f. wiss. Z00L, LXVI, 521-604. 1899.

134. Shelford, Victor E. Reactions of Certain Animals to Gradients of
Evaporating Power of Air. A Study in Experimental Ecology. With
a Method of Establishing Evaporation Gradients by V. E. Shelford and
E. O. Deere. Biol. Bull. July, 1913.

135. Shimek, B. The Prairies. Bull. Lab. Nat. Hist. State Univ. Iowa,
April, 191 1, pp. 169-240.

136. Sherff, E. E. The Vegetation of Skokie Marsh. Bot. Gaz., LIV,
PP- 415-35. 1912.

137. Felt, E. P. Insects Affecting Park and Woodland Trees. N.Y. State
Mus., Mem. VIII, 2 vols. 1906.

Chapter X

138. Emerton, J. H. Common Spiders. Boston. 1902.

139. Dickerson, M. C. The Frog Book. New York. 1907.

140. Hine, J. S. Habits and Life Histories of Some Flies of the Family
Tabanidae. U.S.D.A., Div. Ent., T.S., 12. 1906.

141. Woodruff, F. M. Birds of the Chicago Area. Bull. VI. N.H. Surv.,
Chicago Academy of Sciences. 1907.

142. Merriam, C. H. Mammals of the Adirondack Region. New York.
1886.

143. Seton, E. Thompson-. Life Histories of Northern Animals. New
York. 1909.

144. Pearl, R. The Movements and Reaction of Fresh Water Planarians.
Qr. Jour. Micro. Sci., XLVI, 509-714. 1903.

145. Smith, J. B. Mosquitos Occurring in the State and Their Habits, Life
History, etc. Rep. N.J. Exp. Sta., 1904.

146. Marsh, C. D. A Revision of the N.A. Species of Cyclops. Trans. Wis.
Ac. Sci. Arts and Letters, XVI, 1067-1134. 1910.

146a. . A Revision of the N. A. Species of Diaptomus. Ibid., XV,

380-516. 1907.

147. Sharpe, R. W. A Further Report on the Ostracoda of the United
States National Museum. Proc. U.S. Nat. Mus., XXXV, 399-430.

148. Holmes, S. J. Description of a New Species of Branchipus from Wis-
consin, with Observations on Its Reactions to Light. Wis. Ac. Sci.
Arts and Letters, XVI, 1252-55. 1910.

149. Wolcott, R. H. A Review of the Genera of the Water Mites. Trans.
Am. Micro. Soc, pp. 161-243. 1905.

150. Lugger, Otto. Bugs Injurious to Cultivated Plants. Bull. 69, Minn.
Agri. Exp. Sta. 1900.

151. Shelford, V. E. Life Histories and Larval Habits of the Tiger Beetles
(Cicindelidae). Linn. Soc. Jour. Zool., XXX, 157-84. 1909.

334 ANIMAL COMMUNITIES

151a. Shelford, Victor E. The Life-History of a Bee-Fly (Spogostylum anale
Say) Parasite of the Larva of a Tiger Beetle (Cicindela scutellaris Say
var. Lecontei Hald.). Ann. Ent. Soc. of Am., VI, 213-25. 1913.

152. Ruthven, A. G., Thompson, C, and Thompson, H. The Herpetology
of Michigan. Mich. Geol. and Biol. Survey Pub. 10, Biological Series
3. 1912.

153. Reed, C. A. Bird Guide; Birds East of the Rockies. Worcester,
Mass. 1908.

Chapter XI

154. Packard, A. S. Insects Injurious to Forest and Shade Trees. U.S.
Ent. Com. Bull. 7. 1881.

155. Lugger, O. Beetles Injurious to Fruit-producing Plants. Bull. 66,
Minn. Agri. Exp. Sta. 1899.

156. Blatchley, W. S. On the Coleoptera Known to Occur in Indiana.
Bull. I, Ind. Dept. Geol. and Nat. Res. 1910.

157. Ditmars, R. L. The Reptile Book. New York. 1904.

157a. Fowler, H. W. The Amphibians and Reptiles of New Jersey. Report
N.J. Museum, 1906.

158. Jones, F. M. Pitcher- Plant Insects. Ent. News, XV, 14. 1904.

159. Banks, N. Catalogue of Nearctic Spiders. U.S. Nat. Mus. Bull. 72.
1910.

160. Hopkins, A. D. Report on Investigations to Determine the Cause of
Unhealthy Conditions of Spruce and Pine from 1880-93. Bull. 56,
W.Va. Agri. Exp. Station. 1899.

161. . Insect Enemies of Forest Reproduction. Year Book of U.S.

Dept. Agri., pp. 249-56. 1905.

162. Stone, W., and Cram, W. E. American Animals. New York. 1905.

163. Lugger, Otto. Lepidoptera of Minnesota. 4th Ann. Rep. State Exp.
Sta. Minn. 1899.

Chapter XII

164. Folsom, J. W. Insect Pests of Alfalfa and Clover. 25th Ann. Rep.
State Ent. 111., pp. 41-123; also Exp. Sta. Bull. No. 134. 1909.

165. Williston, S. W. Manual of North American Diptera. New Haven.
1908.

166. Surface, H. A. Lampreys of Central New York. Bull. U.S.F.C. 1897,
pp. 209-15. 1898.

167. Snow, Laetitia M. The Microcosm of the Drift Line. Am. Nat.,
XXXVI, 855-64. 1902.

168. Needham, J. G. The Beetle Drift on Lake Michigan. Canadian Ento-
mol., p. 294. 1904.

169. Herms, W. B. An Ecological and Experimental Study of the Sar-
cophagidae with Relation to Lake Beach Debris. Jour. Exp. Zool., IV,
45. 1907.

BIBLIOGRAPHY 335

170. Shelf ord, V. E. Preliminary Note on the Distribution of the Tiger
Beetles and Its Relation to Plant Succession. Biol. Bull., XIV, pp.
9-14. 1907.

171. Scudder, S. H. Butterflies of Eastern United States and Canada.
3 vols. Cambridge , Mass. 1889.

172. Banks, Nathan. Spiders of Indiana. 31st Rep. Ind. Dept. Geol. and
Nat. Res., pp. 715-49. 1906.

173. Peckham, G. W., and E. G. Instincts and Habits of Solitary Wasps.
Wis. Geol. and Nat. Hist. Surv., Bull. No. 2, Scientific Series 1. 1898.

174. Forbes, S. A. Insect Injuries to Indian Corn. 23d Rep. 111. State
Entomologist. 1905.

175. Shull, C. H. The Life History and Habits of Anthocharis olympia.
Edw. Ent. News, XIX, March, 1907.

176. Hart, C. A., and Gleason, H. A. Biology of the Sand Areas of Illinois.
Bull. 111. State Lab., VII, Art. VII, pp. 137-272. 1907.

177. Smith, J. B. Insects of New Jersey. (27th Rep. of State Board of
Agric.) 2d ed., Rept. N.J. State Museum, 1909.

178. Marlatt, C. L. The White Ant. U.S. Dept. of Agri., Div. of Entomol-
ogy. Circular 50, 2d series. 1902.

179. Howard, L. O. Insect Book. New York. 1902.

180. Ruthven, Alex. Amphibians and Reptiles. A Biological Survey of
the Sand Dune Region on the South Shore of Saginaw Bay. Mich.
Geol. and Biol. Surv., Publication 4, Biol. Ser. 2, p. 257. 1911.

180a. Baker, H. B. Mollusca: Biological Survey of the Sand Dune Region
on the South Shore of Saginaw Bay. Ibid., Ruthven, p. 121. 1911.

181. Robertson, C. Flowers and Insects. Bot. Gaz., XXVIII, 27-45. 1899.

182. Richardson, H. Monograph on the Isopods of North America. Bull.
54, U.S. Nat. Mus. 1905.

183. Bollman, C. H. The Myriapoda of North America. U.S. Nat. Mus.,
Bull. 46. 1893.

184. Weed, C. M. A Descriptive Catalogue of the Phalanginae of 111.
Bull. 111. State Lab., Ill, 79-87. 1887.

185. Wirtner, P. M. Preliminary List of the Hemiptera of Western Pennsyl-
vania. Ann. Carnegie Mus., Ill, 133-228. 1904.

186. Kirkaldy, G. W. Catalogue of the Hemiptera, Heteroptera. Vol. I,
Cimicidae. Berlin. 1909.

187. Peckham, G. W., and E. G. Sense of Sight in Spiders with Some
Observations on Color Sense. Wis. Ac. of Sci., X, 231-61. 1895.

188. Beutenmuller, Wm. Insect Galls within 50 Miles of New York. Guide

Chapters XIII to XV

Leaflet, No. 16, Am. Mus. Nat. Hist. 1904.

189. Forbes, S. A. 24th Report 111. State Entomologist. 1906.

190. Washburn, F. L. Diptera of Minnesota. 10th Ann. Rep. State Ent.,
Minn. 1905.

336 ANIMAL COMMUNITIES

191. Judd, Sylvester D. Birds of a Maryland Farm. U.S. D. Agr., Biol.
Surv., Bull. 17. 1902.

192. Heilprin, A. The Distribution of Animals. Appleton. 1887.

193. Cowles, H. C. A Textbook of Botany, Part III, "Ecology." New
York. 191 1.

194. Hickson, S. J. On the Species of the Genus Millcpora. P.Z.S.
London, pp. 246, 257. 1898.

195. Wood-Jones, F. Coral and Atolls. London. 1910.

196. Woodruff, L. L. Observations on the Origin and Sequence of the Pro-
tozoan Fauna of Hay Infusions. Jour. Exp. Zool., XII, 205-64. 191 2.

197. Clements, F. E. Research Methods in Ecology. Lincoln, Neb. 1905.

198. Whitford, H. N. The Vegetation of the Lamoa Forest Reserve. Philip-
pine Jour, of Sci., I, No. 4, pp. 373-428; No. 6, pp. 437-682. 1906.

199. Beddard, F. E. Zoogeography. Cambridge. 1895.

200. Lydekker, A. Natural History, II and III. Mammals. Bears no
date.

201. Selous, F. C. African Nature Notes and Reminiscences. London.
1908.

202. Ward, T. Rambles of an Australian Naturalist. 1907.

203. Horn, W. Entomologische Reise Brief aus Ceylon. Deut. Ent. Zeit.,
228-30. 1899.

204. Cockerel, T. D. A. Aspects of Modern Biology. Popular Science
Monthly, December, pp. 540-48. 1908.

205. Coulter, J. M. The Theory of Natural Selection from the Standpoint
of Botany. Fifty Years of Darwinism, 56-71. 1908.

206. Wallace, A. R. Malay Archipeligo. London. 1869.

206a. Hudson, W. H. The Naturalist in La Plata. (Ed. of 1903, Dent,
London.) 1892.

207. Craig, Wallace. North Dakota Life; Plant, Animal and Human.
Am. Bull. Geog. Soc, XL, 321-415. Bibliography. 1908.

208. . The Voices of Pigeons Regarded as a Means of Social Control.

Am. Jour. SocioL, XIV, 86-100. 1908.

209. Tarde, Gabriel. Inter-Psychology. Internat. Quar., VII, 59-84. 1903.

210. Waxweiler, E. Equisse d'une sociologie. Inst. Solvay de Soc. Notes
et Mem., Fasc. 2, 306, Bruxelles. 1906.

211. McGee, W. J. The Relation of Institution to Environment. Smith-
son. Rep., 1895, pp. 701-n. 1896.

212. Mason, O. T. Influence of Environment upon Human Industries or
Arts. Smithson. Rep., 1895, pp. 639-65. 1896.

213. Tower, W. S. Scientific Geography; the Relation of Its Content to
Its Subdivisions. Bull. Am. Geog. Soc, XLII, 801. 1910.

214. Goode, J. Paul. Human Response to the Physical Environment.
Jour. Geog., pp. 333-43- 1894.

BIBLIOGRAPHICAL APPENDIX

(March 4, 1937)

CLASSIFICATION OF COMMUNITIES

Shelford, V. E. 1932. Basic Principles of the Classification of Communities
and Habitats and the Use of Terms. Ecology, 13 : 105-20.
The classification of communities used in this book was based on physical
conditions and physiological response. Since 1913 this viewpoint has been
abandoned because no experiments have been conducted on more important
species of most communities to support a physiological view. The present-day
nomenclature is based on the important organisms. The equivalents are as
follows:

Animal Communities Present-Day

Extensive formation Biotic formation or Biome

Formation Associes

Association except three noted below Associes

Subf ormation Associes

Stratum Layer Socies or Society

Consocies Assembly (provisional)

Mores Mores or life-habit

The following biomes are recognized:

1. Deciduous forest biome; two associations (climax) are present — beech-
maple-(wood frog) and oak-hickory- (green tiger-beetle).

2. The grassland or prairie biome; only one association represented.

3. Large lake biome; the deeper communities of Lake Michigan are some-
times regarded as a biome in a permanent or climax condition. In the case of
these climaxes the term "society" is applied to subordinate groups of animals.
For the nomenclature applied to organisms of various degrees of importance,
etc., see the next citation.

Shelford, V. E., and Olson, S. 1935. Sere, climax, and influent animals with
special reference to the transcontinental coniferous forest. Ecology 16:375-
402.

Chapter I

I. HUMAN ECOLOGY

Murchison, C. 1935. A handbook of social psychology. 1095 pp. Worcester.
Read, C. 1920. The origin of man and of his superstitions. 350 pp. Cam-
bridge.

2. SECONDARY COMMUNITIES

Van Deventer, W. C. 1936. Bird and mammal communities of pastures and
field borders in northern Illinois. Bull. Ecol. Soc. Amer. 17:28.

337

338 ANIMAL COMMUNITIES

3. GENERAL

Bird, R. D. 1930. Biotic communities of the aspen parkland of central
Canada. Ecology 11:358-442.

Downing, Elliott R. 1922. A naturalist in the Great Lakes region. Univer-
sity of Chicago Press. 328 pp. Chicago.

Ewing, H. E. 1909. A system and biological study of the Acarina of Illinois.
Univ. 111. Studies 3 (6) 1359-472, with 8 pis.

Forbes, Stephen A., and Gross, A. O. 1922. The numbers and local distribu-
tion in summer of Illinois land birds. Bull. 111. Nat. Hist. Surv. 4:187-218.

Frison, T. H., and Miller, R. B. 1926. See Shelford (1926).

Hebard, Morgan. 1934. The Dermaptera and Orthoptera of Illinois. 111.
State Nat. Hist. Surv. Bull. 20: 125-279; chapter by H. H. Ross: "Biology
and habits of the orders, and ecological factors affecting Orthoptera,"
pp. 125-35.

Sanborn, Colin C. 1922. Chicago winter birds. Field Mus. Nat. Hist.,
Zool. Lflt. No. 2. 12 pp.

. 1925. The mammals of the Chicago area. Ibid. No. 8. 21 pp.

Shelford, V. E. 191 5. The original habitat and distribution of our native
insect pests. Jour. Econ. Ent. 8:171-74.

. 1926. Naturalists' Guide to the Americas. Baltimore, by various

authors; "Illinois," p. 469.

Van Cleave, H. J. 1927. A study of the characters for the identification of
the snakes of Illinois. Trans. 111. State Acad. Sci. 20:133-36 (41 spp.
enumerated).

Chapter IV

AQUATIC CONDITIONS

Shelford, V. E. 1918. Conditions of existence. Ward and Whipple, Fresh-
water Biology, chap, ii, mi pp. New York.

Chapter V

LARGE LAKES

Adamstone, F. B. 1924. The distribution and economic importance of the
bottom fauna of Lake Nipigon with an appendix on the bottom fauna of
Lake Ontario. Univ. Toronto Studies. "Biol. Series" 25:35-100.

Clements, F. E., and Shelford, V. E. 1937. Bio-ecology. In Press.

Eddy, S. 1927. Plankton of Lake Michigan. Bull. 111. Nat. Hist. Surv.
17:203-32.

. 1932. The plankton of the Sangamon River in the summer of 1929.

111. St. Nat. Hist. Surv. 19:469-86.

. 1934. A study of freshwater plankton communities. 111. Biol.

Mono. 12: 1-93.

BIBLIOGRAPHICAL APPENDIX 339

Eggleton, F. E. 1935. The deep water bottom fauna of Lake Michigan.

Mich. Acad. Arts Sci. and Let. 21 : 599-612.
Hubbs, C. L. 1926. Check list of the fishes of the Great Lakes and tributary

water. Univ. Mich. Mus. Zool. Misc. Pub. 15:1-77.

Chapters VI and VII

STREAMS AND PONDS

Baker, F. C. 1928. Freshwater Mollusca of Wisconsin. Wis. Geol. and Nat.
Hist. Surv. Bull, in two parts. 70:1-494 and 1-482.

Cahn, A. R. 1929. The effect of carp on a small lake. The carp as a domi-
nant. Ecology 10:271-74.

Frison, T. 1929. Fall and winter stoneflies or Plecoptera of Illinois. III.
Sta. Nat. Hist. Surv. Bull. 18:345-409.

. 1935. The stoneflies, or Plecoptera, of Illinois. Ibid. 20:281-

471.

Peterson, W. 1926. Seasonal succession in a chara-cattail pond. Ecology
7:371-78.

Richardson, R. E. 1928. The bottom fauna of the middle Illinois River,
1913-1925 : Its distribution, abundance, valuation, and index value in the
study of stream pollution. 111. Sta. Nat. Hist. Surv. Bull. 17:391-472.

Shelford, V. E. 1914. An experimental study of the behavior agreement
among animals. Biol. Bull. 26:294-315.

Shelford, V. E. and Eddy, S. 1929. Methods for the study of stream com-
munities. Ecology 10:382-91.

Smith, F. 192 1. Distribution of freshwater sponges in the United States.
Bull. 111. Sta. Nat. Hist. Surv. 14:11-31.

Thompson, D. H., and Hunt, F. D. 1930. The fishes of Champaign County.
111. Sta. Nat. Hist. Surv. 19:5-101.

Van Cleave, H. J. 1927. The fairy shrimps of Illinois. Trans. 111. State
Acad. Sci. 20:130-32.

Van Cleave, H. J., and Markus, H. C. 1929. Studies on the life history of
the blunt-nosed minnow. Amer. Nat. 53:530-39.

Welch, P. S. 1935. Limnology. New York.

Chapters XII and XIII

Beal, Geoffrey. 1935. Study of Arthropod population by the method of

sweeping. Ecology 16:216-25.
Blake, I. H. 193 1. A comparison of the animal communities of coniferous and

deciduous forest. 111. Biol. Mon. 10:371-520.
Goellner, E.J. 193 1 . A new species of termite, Rcticulitermcs arenincola, from

the sand dunes of Indiana and Michigan, along the shores of Lake Michigan.

Proc. Ent. Soc. Washington 33(9): 227-34.

340 ANIMAL COMMUNITIES

Holmquist, A. M. 1926. Studies in arthropod hibernation. I. Ecological

survey of hibernating species from forest environments of the Chicago

region. Ann. Ent. Soc. Amer. 19:395-428.
Hubbell, Theodore H. 1929. The distribution of the beach grasshoppers.

Trimcrotropis huroniana and Trimerotropis maritima interior in the Great

Lakes region (Orthoptera, Acrididae). Jour. N.Y. Ent. Soc. 37:31-39.
Park, Orlando. 1929. Taxonomic studies in Coleoptera, with notes upon

certain species of beetles in the Chicago area. I. Jour. N.Y. Ent. Soc.

37:429-36.
. 1929. Ecological observations upon the myrmecocoles of Formica

ulkei Emery, especially Leptinus testacus Mueller. Psyche 36:195-215.
. 1929. Reticulitermes tibialis, Banks, in the Chicago area. Proc.

Ent. Soc. Wash. 31 : 121-26. From upper beach, Indiana dunes; behavior,

life hist., etc.
. 1930. Studies in the ecology of forest Coleoptera (I). Ann. Ent.

Soc. Amer. 23 : 57-80.
. 1931a. Studies in the ecology of forest Coleoptera. II. Species

associated with fungi in the Chicago area. Ecology 12: 188-207.
. 193 ib. The measurement of daylight in the Chicago area and its

ecological significance. Ecol. Mono. 1 : 189-230.
Pearson, J. F. W. 1933. Studies on the ecological relations of bees in the

Chicago region. Ecol. Mono. 3:373-441.
Sanders, N. J., and Shelford, V. E. 1922. A quantitative and seasonal study

of a pine dune animal community. Ecology 3:306-20.
Smith, Vera G. 1928. Animal communities of a deciduous forest succession.

Ecology 9:479-500. (6 different habitats selected in a strip mine area.)
Smith-Davidson, Vera G. 1930. The tree layer society of the maple-redoak

climax forest. Ecology 11:601-6.
. 1932. Effect of seasonal variability upon animal species in total

populations in a deciduous forest succession. Ecol. Mono. 2:305-33.
Strokecker, H. F. 1937. A survey of soil temperatures in the Chicago area.

Ecology 18:162-68.
. 1937. An ecological study of some Orthoptera in the Chicago area.

Ibid. No. 2 (in press).
Talbot, Mary. 1934. Distribution of ant species in the Chicago region with

special reference to ecological factors and physiological toleration. Ecolo-
gy 15:416-39.
Weese, A. O. 1925. Animal ecology of an Illinois elm-maple forest. 111.

Biol. Mono. 9:345-438. (University Woods, 5 mi. from Urbana.)

Chapters XIV and XV

Adams, Charles C. 191 5. An outline of the relations of animals to their in-
land environments. Bull. 111. Sta. Lab. Nat. Hist. 11:3-32.

BIBLIOGRAPHICAL APPENDIX 34I

Adams, Charles C. 191 5. An ecological study of prairie and forest inverte-
brates. Bull. 111. Sta. Lab. Nat. Hist. 11:33-280. See Hankinson
(1915).

Eifrig, C. W. G. 1913. Notes on some of the rarer birds of the prairie part of
the Chicago area. The Auk 30:236-40.

. 1919. The birds of the sand dunes of northwestern Indiana. Proc.

Ind. Acad. Sci. (1918), 289-303.

. 1919. Notes on birds of the Chicago area and its immediate vicinity.

The Auk 36:513-24.
Flint, W. P. 1934. The automobile and prairie wild life. 111. State Nat.

Hist. Surv., Biol, notes No. 3. 8 pp., mimeographed. (Destruction of

animals on highway east of Urbana.) Univ. of 111. Library.
Hankinson, T. L. 191 5. The vertebrate life of certain prairie and forest

regions near Charleston, Illinois. Bull. 111. Sta. Lab. Nat. Hist. 11:281-

303. See Adams (191 5).
Hendrickson, G. O. 1930. Studies on the insect fauna of Iowa prairies.

Iowa State Coll. Jour, of Sci. 4:49-180.
. 1930. Notes on vertebrates of Iowa prairies. Proc. Iowa Acad.

Sci. 37:398-99.
Shackleford, Martha W. 1929. Animal communities of an Illinois prairie.

Ecology 10:126-54.

PRAIRIE AND FOREST EDGE

Carpenter, J. R. 1935. Fluctuation of biotic communities. I. Prairie and
forest ecotone of Central Illinois. Ecology 16:203-12.

METHODS

Forbes, Stephen A. 1928. Concerning certain ecological methods of the
Illinois Natural History Survey. Trans. 111. Sta. Acad. Sci. 21:19-25
(1929). Earlier version in brief in Science 66:405-6. 1927.

Shelford, V. E. 1930. Ways and means of improving the quality of investiga-
tion and publication in animal ecology. Ecology 11:235-237.

. 1929. Laboratory and Field Ecology. 608 pp. Baltimore.

INDEXES

INDEX OF AUTHORS AND COLLABORATORS

Page numbers followed by figures in parentheses are the pages of the Bibliography, the parenthetical
figures being the title numbers; the numbers following the parentheses are the pages on which the articles
are cited by number. Page numbers occurring with no parenthesis in connection are those on which the
authors and collaborators are referred to independently of the Bibliography.

Abbot, C. C, 327 (53c), 34.

Adams, C. C, 326 (35a), 22, 32, 42, 321;

328 (67), 48; 329 (83), 73, 79, 195;

331 (103), 105, no.

Alden, W. C, 328 (60, 61), 44, 46, 47.

Aldrich, J. M., viii.

Allee, W. C, vii, viii, 91, 92, 181, 188;

327 (53), 33> 9i; 327 (56), 35; 328

(73), 58.
Atwood, W. W., 45; 328 (62), 44, 46, 210.
Audubon, J. J., v.

Bachmetjew, P., S33 Ci33)» l6 3-
Baker, F. C, vii, viii; 330 (91), 83, 169,

253, 256; 330 (100), 89, 102, 189, 193,

265.
Baker, H, B., 335 (180a), 253.
Banks, N., vii, viii; 334 (159), 195; 335

(172), 222, 228, 240.
Bates, H. W., v, 275.
Beal, F. E. L., 325 (8), 9, 10.
Beddard, F. E., 336 (199).
Belt, T., v.
Bernard, Claude, v.
Betten, C, vii; 330 (95), 93.
Beutenmuller, William, 265; 335 (188),

258, 260.
Birge, E. A., 61; 328 (74), 59, 60, 125,

321.

Blanchard, Rufus, 325 (15), 13.
Blatchley, W. S., vii; 334 (156), 191, 198,

244, 253, 255, 258, 283.
Bonn, G., 327 (53a), 34, 305.
Bollman, C. H., 335 (183), 253.
Brady, G. S., 130.
Braun, M., 326 (29), 20.
Brehm, A. E., v; 325 (2), 5.
Briggs, L. J., 331 (117), 157, 321; 332

(118), 157,321.
Browning, E. B., 3.

Buffon, v.

Butler, A. W., 331 (108), 130, 132, 150,
181, 229.

Caldwell, O. W., ix.

Chamberlin, T. C, 328 (66), 47.

Chaney, R., viii.

Child, C. M., vii, ix, 108, 177-79; 3 2 6

(37), 22, 23; 326 (37a), 23.
Chittenden, F. H., ix, 291, 293, 295.
Clark, F. N., 330 (90), 77.
Class, Elva, viii.
Clements, F. E., 336 (197), 305.
Cockerell, T. D. A., 336 (204).
Cohnheim, O., 332 (126), 160.
Colton, H. S., 331 (114), 151.
Comstock, J. H., 233.
Congdon, E. D., 332 (123), 159.
Cook, O. F., vii.
Cope, E. D., 327 (39), 24.
Coulter, J. M., ix; 336 (205), 317.
Cowles, H. C, vi, viii, ix, 1, 174, 183, 286,

310; 328 (58), 36,42; 332 (120), 159,

305; 336 (i93), 305, 309.
Craig, W., 336 (207, 208), 314.
Cram, W. E., 334 (162), 196.
Cresson, E. T., viii.
Cunningham, Clara, vii.
Curtis, W. C, 330 (99), 99.

Dachnowski, A., 331 (114a), 151.

Dahl, F., v.

Darwin, Charles, v, 24, 25; 326 (30), 20,

i59.
DeCandolle, 161.
Dickerson, M. C, 333 (139), 169, 195,

234, 256, 283.
Dimmit, B. H., vii, 278.
Ditmars, R. L., 334 (157), 252, 255.

345

346

ANIMAL COMMUNITIES

Eigenmann, C, 327 (41), 25.
Ellsworth, H. L., 326 (20), 14, 15.
Emerton, J. H., ix, 229, 238; 333 (138),

169, 220, 222, 240, 252, 257, 258, 259,

260, 261, 263.

Fabre, J. H., v.

Felt, E. P., 333 (137), 166, 191, 195, 196,
201, 225, 228, 229, 233, 257, 258, 259,
260, 261, 266.

Folsom, J. W., 294; 334 (164), 214, 284.

Forbes, S. A., ix, 283,294; 325 (5a), 9, 17;
325 (n), 10; 326 (26), 10, 17; 329
(79), 7o, 76, 91, 92, 127, 140; 329 (85),
751 330 (89), 76, 77; 335 (i74), 223,
282, 284, 285; 335 (189), 267.

Forel, F. A., v; 329 (76), 62-64, 321.

Fowler, H. W., 334 (i57«), 194-

Fuller, G. D., 332 (119), 158; 332 (119c),
158; 332 (131), 162, 249, 250; 332
(131a, 131b).

Ganong, W. F., 327 (52), 33.

Gerhard, W. J., vii, ix, 196.

Giard, A., v.

Gill, T., 331 (106), 126, 149.

Gleason, H. A., 329 (83, 2), 79, 83; 335

(176), 229.
Goldthwait, J. W., 45; 328 (62, 63, 64),

44, 46.
Goode, J. P., ix; 336 (214), 319.
Gorham, F. P., ix, 60.
Graves, H. S., 332 (124), 159, 321.
Greeley, A. W., 333 (132), 163.

Haase, E., v.
Haddon,A. C., 325 (4), 8.

Hancock, J. L., vii; 327 (40), 25, 34, 181,
190, 195, 198, 215, 218, 223, 226, 227,
232, 235, 241, 252, 255, 259, 260, 262,
266, 268, 270.

Hankinson, T. L., 331 (105), 125, 126,
140, 151.

Hann, J., 332 (125), 160, 161, 162, 163,
321.

Hart, C. A., vii; 335 (176), 229.

Harvey, N. A., vii.

Haswell, W. A., 326 (36), 22.

Heilprin, A., 336 (192), 299.

Heinemann, P. G., viii.

Henshaw, S., viii.

Herms, W. B., 334 (169), 219, 223.
Herrick, C. L., ix.
Herrick, F. H., 327 (49), 32, 34.
Hildebrand, S. F., vii, 130; 329 (84), 73,

78, 84.
Hine, J. S., 329 (83, 8); 333 (140), 170.
Holmes, S. J., 327 (536), 34, 305; 333

(148), 177.
Holt, W. P., 329 (83, 4).
Hopkins, A. D., 334 (160), 195; 334

(161), 195, 196.
Horn, W., 336 (203), 315.
Hortag, M., 326 (28), 20.
Hoskins, W., viii.

Howard, L. O., 221; 335 (179), 256, 267.
Hoy, P. R., 329 (82a), 80.
Huber, P., v.

Hudson, W. H., iv; 336 (206a), 317.
Huntington, E., 332 (127), 160

Indian Affairs, Commissioner of, 325

(16), 13.
Isely, F. B., 188; 330 (99a).

Janet, C., v.

Jennings, H. S., ix; 327 (44), 27, 34, 77,

299, 3o°; 33o (87, 88), 75, 76, 77.
Johannsen, O. A., 330 (98), 144.
Johnstone, J., 327 (47), 31, 35, 58, 66, 68.
Jones, A., 326 (23), 14.
Jones, F. M., 334 (158), 193-
Juday, C., vii, 133; 328 (74), 59, 60, 125;

331 (104), 125; 331 (no, in), 133.
Judd, Sylvester D., 336 (191), 274.

Kellogg, V. L., ix, 225, 270, 272.
Kennicott, R., 326 (22), 14, 15, 171, 196,

241, 289.
Kent, W. S., 75.

Kingsley, J. S., 326 (33), 21; 330 (ggb).
Kirkaldy, G. W., 335 (186), 257.
Kirkland, A. H., 325 (10), 9.
Kirkland, J., 325 (14), 13.
Kofoid, C. A., 329 (75, app.), 74; 329

(77), 67, 103, 125,321.
Kunz, G. F., 326 (31), 21.
Kwiat, A., vii.

Lamarck, J. B., 24, 25.
Lane, A. C., 455 328 (65), 44.

INDEX OF AUTHORS

347

Lefevre, G., 330 (99), 99.

Leidy, J., 75, 130.

Leverett, F., 45; 328 (59), 44.

Lillie, F. R., ix.

Livingston, B. E., 332 (130, 130a, 1306,

130c), 162.
Loeb, J., vi; 328 (72), 58, 305.
Lugger, O., 88, 234; 333 (150), 180, 191,

273; 334 (i55), 192, 201, 233; 334

(163), 199, 202, 215.
Lydekker, A., 336 (200).
Lyon, E. P., 323 (94), 91, 101.

MacGillivray, A. D., vii; 331 (109), 132.
Marlatt, C. L., ix, 220, 265, 282; 335

(178), 252.
Marsh, C. D., vii; 329 (78), 67; 333

(146, 146a), 176.
Marsh, M. C, 326 (24), 17; 328 (71), 58,

59.
Mason, E. G., 326 (19), 14.
Mason, O. T., 336 (212), 319.
Mast, S. O., 327 (45), 28, 159.
McFarland, Joseph, 326 (27a).
McGee, W. J., 336 (211), 319.
McLane, J. W., 331 (117), 157.
McNutt, W., 332 (119a), 158.
Meek, S. E., vii, ix; 329 (84) 73, 78, 84.
Merriam, C. H., 327 (48), 32, 299; 333

(142), 171, 189, 195, 196, 233, 238.
Meyers, I. B., 220.

Milner, J. W., 329 (81), 73, 80, 83, 84.
Mobius, K., v.
Moore, B., 327 (43), 26, 321.
Moore, J. P., vii; 330 (91a), 83.
Morse, A. P., 329 (83, 6).

Needham, J. G., 329 (83, 7); 330 (95),
93, 96, 146; 330 (96), 95; 330 (98), 99;
334 (168), 219.

Newman, H. H., 331 (107), 130.

Nichols, Susan P., viii.

Nichols, W. R., 326 (25), 17.

Ortmann, A. E., vii; 330 (101), 104.
Osborn, H. F., 327 (38), 24.
Osburn, R. C., vii.
Osgood, W. H., viii.

Packard, A. S., 334 (154), 19*-
Park, W. H., 326 (27), 20.

Parker, T. J., 326 (36), 22.

Parkman, F., 326 (18), 14.

Pearl, R., 333 (144), 172.

Pearse, A. S., 330 (101a).

Peckham, G. W. and E. G., 223; 335

(173), 222, 252, 255, 258; 335 (187),

258.
Peet, M. M., 329 (83, 12).
Pettenkoffer, M., 162.

Reed, C. A., 334 (153), 181, 189.
Reed, H. S., 332 (121), 159.
Reeves, C. D., 330 (97), 95.
Reighard, J., 327 (50), 32, 90, 91, 101.
Reynolds, John, 326 (20a), 14, 15.
Richardson, H., 335 (182), 253.
Richardson, R. E., 329 (79), 70, 91, 92,

99, 127, 140.
Riddle, O., 327 (46), 31.
Riley, C. V., ix, 201, 234, 238.
Ritter, W. E., 325 (1), 5.
Robertson, C., 335 (181), 253, 255.
Romanes, G. J., v.
Roosevelt, T., 35; 325 (3), 5, 313.
Ruthven, A. G., 325 (7), 9; 329 (83, n);

334 (152), viii, 181; 335 (180).

Salisbury, R. D., ix; 328 (57), 36, 44, 61,

73, J 57; 328 (60), 44.
Schimper, A. F. W., 328 (58a), 36, 38, 313,

314.
Schmarda, L. R., v.
Schreiner, O., 332 (121), 159.
Scudder, S. H., 335 (171), 222.
Selous, F. C., 336 (201).
Semper, K., 327 (51), 1,33.
Seton, E. T., 333 (143), 171, 195, 269.
Severin, S., 10.

Shantz, H. L., 332 (118), 157, 321.
Sharp, D., 326 (34), 21.
Sharpe, R. W., vii, 144; 333 (147), 177.
Shelford, Mabel Brown, vii, 13-15.
Shelford, V. E., 325 (6), 9, 32, 59, 68, 69,

136, 151, 152; 325 (13), 12, 33, 311;

327 (55), 34, 3 6 , 37, 38, 157, 161, 209,

211, 215, 301, 302, 304, 315; 328 (73),

58; 330 (92), 90, 99, 105, 309; 33i

(112), 136, 152; 331 (115), 157, 222.

225, 227, 233; 333 (134), 163; 333

(151), 211, 215, 219, 252, 256; 334

(151a), 229; 335 (170), 219, 225, 227,
233.

348

ANIMAL COMMUNITIES

Sherff, E. E., 333 (136), 165.

Sherman, J. D., 330 (99c), 99, io2 > I0 4,
105, 180, 193.

Shimek, B., S33 C^), l6 4-

Shull, C. H., 335 (175), 227, 257.

Smith, B. G., 330 (93), 91.

Smith, Frank, vii.

Smith, H. M., ix, 79.

Smith, J. B., 176, 179; 333 (145), 174;

335 (i77), 252, 253, 259, 260, 261.
Smith, S. I., ix; 329 (80), 73, 76, 78.
Snow, Julia W., 330 (86), 75.
Snow, Laetitia M., 334 (167), 219.
Sparks, J., 325 (17), 13.
Stahl, W. S., viii.
Stanfuss, M., 327 (42), 25.
Stephens, T. C., viii, 170, 171, 175, 228,

229.
Stevenson, C. H., 326 (32), 21.
Stimpson, W., 329 (82), 73, 78, 80, 84.
Stone, W., 334 (162), 196, 227.
Strong, R. M., viii.
Surface, H. A., 325 (9, ga), 9; 334 (166),

219.

Tarde, G., 336 (209), 318.

Thompson, C., 334 (152), 181.

Thompson, H., 334 (152), 181.

Thomson, J. A., 6.

Titcomb, J. W., 331 (113), 140, 142.

Titus, E. S., 329 (83, 9).

Tower, W. S., 336 (213), 319.

Transeau, E. N., 50, 51, 64; 328 (69),

164,321; 328(70); 332 (122), 159.
Turner, C. H., ix.

VanHise, C. R., 331 (116), 157.
Verworn, Max, 326 (35), 22, 27, 2S,
300-

Visher, S. S., vii, viii, 190.
Voit, C., 162.

Wagner, George, 331 (no), 133.
Walker, A. C, 332 (128), 160, 299.
Walker, Bryant, 329 (83, 5), 83; 329

(75, app.), 80, 83-85.
Wallace, A. R., v; 336 (206), 317.
Ward, H. B., 329 (75), 62, 64, 67, 73,

74, 82, 83-85.
Ward, T., 336 (202).
Warming, E., 325 (12), 12.
Washburn, F. L., ix, 225, 239, 290, 291;

335 (190), 272, 285.
Waxweiler, E., 336 (210), 319.
Weather Bureau, 328 (68), 49.
Webb, Sidney, 325 (5), 8.
Weckel, A. L., vii; 331 (102), 104.
Weed, C. M, 335 (184), 253.
Wells, M. M., vii, ix.
Wheeler, W. M., 327 (54), 34, 252, 253,

255; 329 (83, 10).
White, G., v.

Whitford, H. N., 336 (198), 311.
Wickham, H. F., vii.
Wiesner, J., 160.
Williston, S. W., 89, 217, 224, 271, 272;

334 (165), 214, 217, 222.
Wirtner, P. M., 335 (185), 257, 259.
Wolcott, A. B., vii, 196; 329 (83, 3), 193.
Wolcott, R. H., vii, 130; 333 (149), 177.
Wood, F. E., 326 (21), viii, 14, 15, 34,

192, 196, 255.
Wood-Jones, F., 336 (195), 305, 309.
Woodruff, F. M., 333 (141), 171, 181.
Woodruff, L. L., 336 (196), 305, 309.

Yapp, R. H., 332 (129), 160, 165.

Zon, R., 332 (124), 159,321.

INDEX OF SUBJECTS

Absorption of dissolved foods by aquatic
animals, 58.

Acclimatization, isopods, 92.

Acorns: eaten by squirrels, 233; weevils,
233.

Activities: classification of, 31; dis-
tribution and, 299-305; environment
and, 26-30; form and, 26-27; most
limited, 304.

Adaptation: 24-26; of May-fly nymphs,

96.
African game, 7.
Age of habitats: 44; forest, 218, 247;

lakes, 133-34; ponds, 138, 152;

quantity of life and, 68-69; streams,

86, 1 10-14.

Agriculture: communities of, 13, 15-17;

near cities, 19.
Algae: 59, 65, 70; depth limit in Lake

Michigan, 74; filamentous, 131, 148;

on mollusk shells, 126.

Ammonia: in sewage, 17; in air and
water, 59, 60; in nitrogen balance, 66;
reactions of fishes to, 60.

Amphibians or Amphibia, scientific
names:

— Acris gryllus, 135, 169, 296.

— Ambly stoma tigrinum, 149, 278, 282,

296.
— Bufo lentiginosis , 187, 296.
— Chorophilus nigritus, 195, 206, 283, 296.
— Diemictylus viridescens, 121, 149, 156.
— -Hemidactylium scutatum, 237.
— Hyla:

pickeringii, 194, 195, 196, 205, 207,

234,. 253.

versicolor, 205, 234.
— Necturus maculosus, 130.
— Plethodon:

cinereus, 197, 207, 243, 244, 256.

glutinosus, 181, 183, 207.
— Rana:

catesbeiana, 171.

clamata, 169, 171, 195.

pipiens, 156, 169, 195, 296.

sylvatica, 195, 206, 207, 243, 244, 256.
Amphipods, 69, 70.
Amphipods or Amphipoda, scientific

— Eucrangonyx, 1 74 :

gracilis, 80, 85, 114, 118, 150, 154,
185, 206.
— Gammarus fascialus, 90, 93, 104, 114,

118, 123, 172.
— Hyalella knickerbockeri, 78, 104, 114,

121, 123, 135, 144, 154.
— Pontoporeia hoyi, 80, 81, 85.

Anemotaxis, 161.

Animal organism, 22-33.

Animals: disappearance of, near Chicago,
13-15; economic value of, 20; rela-
tion of, to man, 5-20.

Annelida, 103. See also Leeches.

— Lumbriculus, 1 79 :
inconstans, 185.
— Limnodrilus claparedianus , 83.
Ant-lion, 229, 232.

Ants: 167; aphids and, 234, 255, 290;

swarming of, 227.
Ants, scientific names:
— A phaenogaster:

tennesseensis, 256.

treatae, 188.
— Camponotus, 202:

herculeanus ligniperdus novebora-

censis, 207, 255.

herculeanus pennsylvanicus, 253.
—Dolichoderus mariae, 204.
— Formica:

cinerea neocinerea, 298.

fusca, 204, 205, 207.

fusca subsericea, 187.

subpolita neogagates, 282, 297.
— Lasius:

niger americanus, 227, 252.

umbratus mixtus aphidicola, 234, 255.
— Myrmica rubra scabrinodis, 288, 297.
— Ponera coarctala, 187.
Aphids: 167, 245; ants and, 234, 290;
cherry, 223-24; consocies, 37, 214, 290;
fecundity of, 18, 35; grain, 18; housed
by ants, 234.
Aphis-lions, 167, 290-91.
Aquatic conditions: 58-67; chemical,
58-60; food, 65-67; physical, 60-65.
Ash: 190; galls of midrib, 192.
Association: 37; defined, 38; listed, 39-
41.

349

3 So

ANIMAL COMMUNITIES

Atmometer, 162, 164.

Atmosphere: 159; composition, 59;

evaporating power, 159-62, 248-50;

currents in, 161.

Back-swimmers, 65,90, 117, 123, 132, 135,

148, 151, 155.
Bacteria: denitrification, 66; nitrifying,

66; nitrogen-fixing, 66; number and

age of ponds, 68; number and quantity

of life, 66; soil, 159.
Bacteria, scientific names:
— Azotobacler, 66.
— Bacterium actinopelk, 66.
— Clostridium, 66.
— Nitrobacter, 66.
— Nitrococcus, 66.
— Nitrosomonas, 66.
Badger, 15, 167, 288.
Balance in nature: 17-18; restored after

the rise of a pest, 18; after disturbance

in water, 71.
Bark beetle: destroyer, 195; habits on

tamarack, 195; on pine, 228.
Bass, black: 22, 23; large-mouthed, 70,

71, 85, 115, 120, 126, 127, 141, 156;

rock, 85, 99, 119; small-mouthed, 85,

99, 119, 120; warmouth, 130, 142,

156.
Bear, black, 14, 15, 201, 237, 245.
Beaver, 15, 101, 199.
Beech woods, 158, 242-52.
Beetles, aquatic: brook, 78, 93, 96, 98,

101, 102, 104, 118, 121, 123; preda-

ceous diving, 65, 90, 102, 104, 121, 131,

i$$i I 5 I > water scavenger, 65, 104,

131, 151, 185.

Beetles, aquatic, scientific names:
— Agabus, 90 :

semipunctatus, 151.
— Aphodius fimetarius, 185.
— Chrysomelidae, 132.
— Coptotomus inter rogatus, 135.
— Cybister fimbriolatus, 149.
— Dascyllidae, 179, 185.
—Donatio,, 65, 123, 135, 151.
— Dytiscidae, 65, 102, 104, 131, 151, 185.
— Elmis, 121:
' fastiditus, 93, 118.

4-notatus, 123.

quadrinotatus , 104.
— Haliplidae, 65.

— Hydro philidae, 65, 104, 131, 151, 185.
— Hydro porus, 90:

mellilus, 102.

vittatus, 121.
— Parnidae, 78, 96, 98, 101, 102.

— Psephenus, 78, 96.

Beetle: bark, 195, 228; boring, 191, 206,
217, 240; click, 234, 255, 282, 297;
ground, 167, 179, 180, 185, 186, 190,
217, 205, 206, 272, 243; lady, 167,
293; May, 167, 290; relation to moist-
ure, 247; snout, 223 238, 282, 284;
soldier, 167.
Beetles, terrestrial, scientific names:
— Acmaeodera pulchella, 297.
— Acropterys gracilis, 277.
— Alans:

myops, 255.

oculatus, 253.
— Allopoda lutea, 207.
— Amara:

angustata, 296.

polita, 204.
— Anisodactylus inter punctatus, 218.
— Anthophilax attenuatus, 245.
— Paris confinis, 204.
— Bassareus lativittis, 258.
— Bembidium, 185, 198:

car inula, 179, 180, 186.

variegalum, 186.
— Boletobius cinctus, 261.
— Boletotherus bifurcus, 244, 261.
— Brachybamus electus, 204.
— Buprestidae, 191, 201.
— Calalhus gregarius, 217.
— Callida punctata, 276, 277.
— Calligrapha, 267:

multipunciata, 188, 207.

scalaris. 241, 260.
— Cardiophorus cardisce, 255.
— Cerambycidae, 191, 206, 217, 240.
— Ceruchus piceus, 253.
— Chalepus:

homii, 188.

nervosa, 207.

scapularis, 208.
— Chelymorpha argus, 277.
— Chlaenius aestivus, 296.
— Chrysochus auratus, 284, 297.
— Cicindela:

cuprascens, 180, 186, 219.

formosa generosa, 225, 226, 252.

hirticollis, 179, 180, 186, 219, 221,

315.

lepida, 40, 120, 223, 252, 316.
purpurea limbalis, 40, 210, 211, 212,
213, 254, 302.
repanda, 181, 186.
saulcyi, 315.

scutellaris lecontei, 40, 182, 227, 229,
230, 252, 316.

sexguttata, 41, 215, 216, 234, 254,
256, 316.

tranquebarica, 182.
— Cleridae, 194.

INDEX OF SUBJECTS

351

Beetles — Continued:
— Coccinelidae, 224.
— Coptocycla:

bicolor, 205, 277.
clavata, 206.
signifera, 277.
— Crepidodera helxines, 108.
— Cryptocephalus:
cinctipennis , 297.
venustus, 284, 297.
— Cryptorhopalum hacmorrhoidale, 207.
— Cryptorhynchus lapathi, 267, 276.
— Cycloneda, 293:

sangninea munda, 298.
— Cyphon:
padi, 207.
variabilis, 207.
— Dascyllidae, 207.
— Dectes spinosus, 277.
— Dendroctonus simplex, 195.
— Dermestes lardarius, 16.
— Dermestidae, 207, 217, 219.
— Desmoris scapalis, 297.
— Diabrotica:

12-punctata, 187, 284, 297.
vittata, 187.
— Diaperis hydni, 234, 253.
— Diplochila laticollis, 296.
— Disonycha quinquevittata, 224, 258.
— Ditoma qua dri guttata, 259.
— Donacia subtilis, 297.
— Doryphora clivicollis, 270, 277.
— Eburia quadrigeminata, 119.
— Elaphidion villosum, 239, 241, 277.
— Elateridae, 234, 255.
— Endalus limatulus, 284, 297.
— Epicuata, 270:
marginata, 277.
pennsylvanica, 277.
— Eupsalis minuta, 201, 255.
— Eustrophus tormentosus, 234.
— Galerita janus, 253.
— Geopinus incrassatus, 220.
— Geotrupes splendidus, 256.
— Haltica ignila, 192.
— Helophorus linealus, 204.
— Hippodamia, 293:
parenthesis, 292.
— 7^5 grandicollis, 228, 258.
— Lacon rectangular is, 255.
— Lampyridae, 205.
— Languria:

angustata trifasciata, 277, 255
gracilis, 205.
mozardi, 293, 294.
— Z,e6m atriventris, 277.
— Limonius inter stitialis, 208.
— Ziwa, 267:

scripta, 276.
— Listotrophus cingulatus, 207.

— Listronotus:

callosus, 204.

inaequalipenntSy 204.
— Lixus, 293:

macer, 277.

concavus, 295.
— Lucidota:

atra, 188.

punctata, 188.
— Megalodacne heros, 247.
■ — Megilla, 293:

maculata, 292, 293.
— Melandryidae, 206, 207.
— Melanotus:

communis, 256.

fissilis, 282, 297.
— Meracantha contracta, 253.
— Monachus saponatus, 284, 297.
— M ordellistena:

aspersa, 188.

connata, 298.
— Nitidulidae, 267.
— Nodonota tristis, 188, 258, 297.
— Oberea tri punctata, 277.
— Odontota nervosa, 260, 297.
— Orthosoma brunneum, 239, 253.
— Pachybrachys, 293, 298:

abdominalis, 188.
— Pachyscelus laevigatas, 188.
— Parandra brunnea, 190.
— Passalus cornutus, 239, 240, 242, 247.
— Pelidnota punctata, 208, 277.
— Penthe pimelia, 247.
— Phloeotrya quadrimaculata, 207.
— Photinus:

corruscus, 207.

punclulatus, 298.
— Piss odes strobi, 196.
— Platynus, 192:

affinis, 296.

decens, 205.

picipennis, 204.
— Plectrodera scalator, 225, 258.
— Podabrus:

basilar is, 261.

rugulosus, 208.
■ — Polygraphus rufipennis, 194, 195, 206.
■ — Prionus, 233, 239.
— Psyllobora 20-macidata, 207.
— Pterocyclon mali, 246.
— Ptero stick us:

adoxus, 206, 207, 243.

coracinus, 206.

lucublandus , 205.

pennsylvanicus , 206.

wj»i 2 55-
— Ptilinus ruficornis, 245.
— Ptilodactyla serricollis, 188.
— Pyractomena borealis, 188.
— Pyrochroidae, 191, 201, 247.

35^

ANIMAL COMMUNITIES

Beetles — Continued:

— Rhinoncus pyrrhopus, 208.

— Saperda:

concolor, 267, 276.

lateralis, 276.
— Saprinus patruelis, 186, 219.
— Scarabaeidae, 207, 286.
— Silpha surinamensis , 253.
— Sphenophorns, 223:

pertinax, 284.
— Staphylinus violaceus, 256.
— Stereo palpus:

badiipennis, 219.

mellyi, 188.
— Strangalia acuminata, 208.
— Synchroa punctata, 206.
— Tachinus pallipes, 260.
— Telephones lineola, 204.
— Tenebrionidae, 201, 217.
— Tetraopes tetraophthalmus , 270, 297.
— Thanasimus dubius, 194, 195, 206.
— Tharops ruficornis, 247.
— T amicus. See Ips.
— Trirhabda tormentosa canadensis, 276,

293, 297.
— Tritoma unicolor, 244.
— Typophorus:

canellus, 282, 284.

canellus aterrimus, 188, 297.

canellus gilvipes, 2g8.

canellus sellatus, 188.
— Uloma impressa, 255.
— Xanthoma 10-nolata, 241, 260.
— Xylopinus saperdioides, 256.

Behavior rhythms, related to tide, 34.

Bionomics, 32.

Biota, defined, 34.

Birds : economic value of, 8-1 1 ; protec-
tion of, 8-1 1, 57; feeding grounds of
aquatic, 130, 132.

Birds, scientific names:

— Ar delta exilis, 171.

— Empidonax trailli, 190.

— Gallinula galeata, 171.

— Tyrannus tyr annus, 228.

— Xanlhocephalus xanthocephalus, 170.

Bison, 14, 201, 283, 289.

Bittern: American, 171; least, 171.

Blackbird, red-wing, 171, 174, 175;
yellow-head, 170, 171.

Black fly, 87-89, 93, 95, 105, 114, 116,
118.

Blowouts, 229.

Blue racer, 227.

Bluebird, 242.

Bluejay, 242, 244.

Bobolink, 9, 167, 283, 289.

Bobwhite, 269, 275.

Borers: buprestid, 191; cerambycid,
191; of trees, 191; four marked, 191;
common to swamp forest trees, 191.

Bottom: communities of, in Lake
Michigan, 77-80; distribution on,
107, 108; factor, 43; gravel, 91;
important, 64; in deep water, 80; lake,
125; pond, 140, 141; stony, 95;
stream, 86.

Braconids, 290.

Breeding: of aquatic insects, 65; of birds
(see common names of); of brook
fishes, 90-91; of lake fishes, 126; of
mammals (see common names of); of
mites, 129; of musk turtle, 130; of
pond fishes, 141.

Bronzed grackle, 275.

Brook trout, 31.

Brook-mores of sowbug, 90.

Brown thrasher, 268, 275.

Buffalo fish, 130.

Bullhead: 70; speckled, 126, 141, 156;
black, 102, 119, 120, 149, 156; yellow,
156.

Bumblebee, 190.

Bunting: indigo, 268, 274, 275; lark, 289.

Buttonbush, 190.

Cabbage butterfly, 221, 222, 227.

Caddis-flies, 65.

Caddis- worms: caseless, 88, 116; case-
weighting, 125, 126, 135, 140, 143,
155; leaf-tube making, 39, 105, 114,
121, 146, 148, 155, 174, 185; mores of,
126; sand-tube making, 39, 142, 143,
148, 155; sandy bottom, 135; spiral-
cased, 96, 99, 117, 121; stick-using,
101.

Caddis- worms, scientific names:

— Chimarrha sp., 116.

— Goera, 125, 135, 140, 142, 143, 155.

— Helicopsyche, 96, 99, 117, 121.

—Hydropsyche, 39, 79, 93, 94, 95, 96,
105, 107, 118, 121, 123.

— Leptoceridae, 143, 148, 39, 155, 442.

— Limnophilidae, 117.

— Molanna, 125, 134.

— Neuronia, 39, 148, 155, 185.

— Phryganeidae, 105, 114, 121, 146, 148,
174.

— Polycentropidae, 135.

— Rhyacophila, 88.

— Rhyacophilidae, 88.

INDEX OF SUBJECTS

353

Calumet beach, 46.

Carbon dioxide: important to animals,
59, 60; in air, 59; in ponds, 68; in
sewage, 17; in springs, 93; in streams,
86; relation to quantity, 66-70.

Carp, 31, 120, 130.

Carrion: 219; feeder, 219.

Catbird, 268, 275.

Caterpillar: achemon sphinx, 232;
American dagger- moth, 192; cecropia,
198, 199; common to marsh forest
trees, 192; forest tent, 192; hickory-
tussock-moth, 192; maia moth, 26S;
prominent, 232, 233; puss, 232; slug,
233; smeared dagger-moth, 192; vice-
roy, 198, 199; white-marked tussock-
moth, 192.

Catfish, lake, 85. See Bullhead.

Cecidomyiidae, 215, 229.

Center of distribution, 303.

Char a, bottoms covered with, 140, 141,
142, 145; communities, 140-45; not
good animal food, 142.

Characters of communities of forest, 250,
251.

Chicago region: climate, former, 47,
present, 49; extent, 48; guide to, 50;
topography, 48; vegetation, 49.

Chickadee, black-capped, 229.

Chipmunk, 34, 196, 269, 274.

C ho r data, 2.

Chub : creek (See Horned dace) ; river,
119.

Cicada: 227; nymphs, 262, 268.

Circulation of water: lake, 60, 61;
pond, 136; stream, 60.

Cladocerans, 76, 83, 134, 173.

Cladocerans or Cladocera, scientific
names:

— Aero perus harpae, 134.

— Bosmina, 76:

obtusirostris, 134.

— Ceriodaphnia, 134, 152:
pulchella, 152.
quadrangula, 152.
reticulata, 134.

— Chydorus sphaericus, 134.

— Daphne:

hyalina, 76, 83.
retrocurva, 76.

— Daphnia. See Daphne.

— Daphnidae, 278.

— Diaphanosoma brachyurum, 134.

— Leptodora hyalina, 76.

— Macrothrix rosea, 134.

— Pleuroxus denticulatus , 134.
— Polyphemus pediculus, 134.
— Scapholeberis mucronata, 134.
— Simocephalus serrulatus, 134.

Classification: ecological, 2; taxonom-
ic, 2.

Climate: 49; former, 47.

Climatic communities, 38-41, 42, 49,
50, 310-15.

Coloration, 25.

Combinations of factors, 161-66.

Communities: basis, 33, 34; behavior
in, 27; classification, 37-41; conver-
gence, 309-12; decline of primeval,
13-16; defined, 3; man-made, 12-18;
mapped, ii; of buildings, 16; of culti-
vated lands, 16; of forest, 189-261;
of forest border region, 39-41; of
forest margins, 262-77; of large lakes,
73-85; of marshes, 169-80; of orchards,
16; of ponds, 136-56; of prairies, 287-
98; of roadsides, 12, 16, 275, 276; of
small lakes, 125-35; of springs, 93;
of streams, 86-123; of thickets, 262-
77; relations of animals in, 35, 70-71,
166-68.

Conditions of existence: aquatic, 58-72;
terrestrial, 157-67.

Consocies: aphid, ^, 214, 234, 290;
beech log, _ 245-47; defined, 37; log,
150-51; pitcher-plant, 40, 193; pool,
39, 90; spring, 39, 93; temporary rapids,
39, 87, 88.
Convergence of communities: 309-12;

of habitats, 93, 94.
Coot, 170.
Copepods: fecundity of, 35; in young

ponds, 173.
Copepods, scientific names:
— Canthocamptus northumbricus, 206.
— Cyclops, 278:

albidus, 134, 152, 206.
bicuspidatus, 76, 83.
leuckarti, 83.
prasinus, 83.
serrulatus, 134, 206.
viridis, 152.

viridis americanus, 176, 206.
viridis brevispinosus, 134.
— Diaptomus, 179, 278, 279:
ashlandi, 83.
leptopus, 152.
oregonensis, 83.
reighardi, 135, 152.
stagnalis, 176, 179, 185.
— Epischura lacustris, 83.

354

ANIMAL COMMUNITIES

Correspondence of communities, 313-15.

Cowbird, 274, 275, 290.

Coyote, 15, 167, 286.

Crane-fly: larvae, 190; adults, 191.

Crappie, 115, 120, 126, 140.

Crayfish: 69, 70, 199; behavior in

drought, 90.
Crayfish, scientific names:
— Cambarus:

blandingi acutus, 114, 116, 154.

diogenes, 114, 121, 199, 204, 296.

gracilis, 296.

immunis, 144, 154.

propinquus, 85, 90, 104, 114, 116,

118, 121, 123.

virilis, 85, 90, 105, 114, 116, 121,

126, 135.
Creeks, sluggish, 102.
Cricket, striped shrub, 266.
Crickets, 167.
Crossbill, 229.
Crow, 242.

Crustaceans or Crustacea: 67; as food,
20; pelagic, 76; deep-water, 80. See
Entomostraca, Crayfish, Sowbugs, Am-
phipods, Shrimps, and Mysis.
Current: water, 43, 61, 73, 86: about
stones, 61; intermittent, 90; swift,
94-99; reactions to, 29, 34, 91.
Cutworms, hibernating, 201.

Dace: black-nosed, 91, 92, 106, in, 115;

horned, 90, 91, 106, in, 115, 119, 120;

red-bellied, 91, in, 115, 119.
Damsel-flies, scientific names:
— Argia, 121:

putrida, 116.
— Calopteryx maculata, 99, 105, 116, 118.
—Enallagma, 117, 135, 155, 185.
— Ischnura verticalis, 104, 123, 132, 135,

155-
— Lestes, 155.

Damsel-fly nymphs, 99, 104, 105. 116,
117, 118, 121, 123, 130, 132, 135, 155,
185.

Darter: 34, 97; banded, 95, 97, 119,
120; black-sided, 95, 97, 120; Johnny,
84, a 1 * 95, io 5> 115, 119. !20, 126, 135;
least, 84, 119; rainbow, 95, 97, 119,
120.

Day and night, responses associated
with, 30.

Deep-water communities of Lake Michi-
gan, 80.

Deer, 14, 201, 238, 245, 269.

Desmids, 76.
Diatoms, 76.
Dickcissel, 167, 283, 289.
Digger-wasps, habits of, 222, 231.
Dip-nets, illegal, 57.
Disagreement of communities, 307-8.
Dissolved foods of aquatic animals, 58.
Diurnal depth migration of Entomostraca

and rotifers, 77.
Dogfish, 156.

Dormancy: of eggs, 177-80; of winter

bodies, 129.
Dragon-flies, adult, food habits, 227.
Dragon-flies, scientific names:
— Aeschna, 118:

constricta, 90, 114.
— Aeschnidae, 104, 117.
— Anax, 142:

jicnius, 132, 135, 155.
— Basiaeschna Janata, 121.
— Celithemis eponina, 155.
— Cordulegaster obliquus, 90, 114.
— Epiaeschna heros, 155.
— Gomphus:

exilis, 99, 116, 121.

spicatus, 143, 155.
— Leucorhinia, 142:

intacta, 146, 147, 155.
— Libellula pulchella, 155.
—Libellulidae, 104.
— Macromia taeniolata, 103, 123.
— Pachydiplax longipennis, 155.
— Plathemis lydia, 116.
— Tetragoneuria cynosura, 114, 135.
— Tramea, 142:

lacerata, 155.
— Sympetrum, 155:

rubicundulum, 155.
Dragon-fly nymphs, 90, 93, 99, 103, 104,
116, 117, 118, 121, 123, 132, 135, 142,
143, 146, 147, 155.
Drift, animal, 219.

Droughts: 90; behavior of stream
animals in, 92, 105; force animals
downstream, 106.
Duck, wood, 181, 190, 191.
Dunes, moving, 229.

Earthworms, 20, 190, 262, 269.
Ecological agreement: of communities,

305 ; of individuals, plants, and animals,

304-8; of species, 315.
Ecological equivalence, 34.
Ecology: content of, 32, 299-318;

genetic, 113, 137, 247-52, 308-15;

INDEX OF SUBJECTS

355

Ecology — Continued:

organization of, 23, 25, 32, ^; physio-
logical, 299-308; relation to biology,
315-18; relation to geography, 318-20;
relation to sociology, 318.

Economic problems: 9-1 1; preservation
of breeding, grounds of fishes, 126.

Eel, 84.

Egg-laying, of aquatic insects, 107, 108.

Electricity, 161.

Elk, 14, 201, 269.

Elm: American, 190; coxcomb gall of,
192.

England: bird protection in, 8; man-
made nature in, 11.

Entomostraca, 20, 69, 70, 71, 76, 133, 152,
176, 179, 204; {see Cladocerans,
Copepods, and Ostracods); the food
of young fishes, 76.

Environment: 42-56, 58-67, 157-66;
299; factor of, 42-44; relation to,
22-33.

Equilibration: of aquatic communities,
diagram illustrating, 70; of land
communities, 166-69; diagram illus-
trating, 167.

Erosion, important on clay bluffs, 209,
210.

Ethology, 32.

Evaporation: 162-65; effect upon
animals, 162-63; expression of con-
ditions, 162; of different habitats,
164; in forest stages, 248-49; reactions
to, and death by, 163.

Evaporimeter: Piche, 164; porous cup,
162.

Factors in distribution, 299.
Fairy shrimp, 177-79, 185, 278-79.
Field study: legal aspects, 56; methods,

321-24.
Fish: breeding of, 126; destroyed by
lampreys, 219; feeding, 130; longi-
tudinal distribution in streams, 109,
no, 115, 119, 120; protection, 56, 57;
traps, 80.
Fish, scientific names:
— Abramis, 65:

crysoleucas, 102, 115, 119, 120, 142,
143, 156.
— Acipenser rubicundus, 85.
— Ambloplites rupestris, 85, 99, 119.
— Ameiurus:

lacustris, 85.

melas, 102, 119, 120, 149, 156.

natalis, 156.
nebulosus, 156.
— Amia calva, 156.
— Anguilla rostrata, 84.
— Aphredoderus sayanus, 120.
— Aplodinotus grunniens, 85.
— Argyrosomus:

artedi, 82, 84.

hoyi, 81, 82, 85.

nigripinnis, 81, 82.

prognathic, 79, 80, 82, 85.
■ — Boleosoma nigrum, 84, 91, 95, 105, 115,

119, 120, 135.
— Campostoma anomalum, 119, 120.
— Car pi odes, 85.
— Catostomus:

catostomus, 84.

commersonii, 84, 91, 92, 106, 115,

119, 120.

nigricans, 84, 119.
— Chaenobryttus gulosus, 142, 156.
— Chrosomus erythrogaster, 91, in, 115,

119.
— Coregonus clupeiformis , 82, 85.
— Crislivomer namaycush, 79, 82, 85.
— Cyprinus carpio, 120.
— Erimyzon sucetta, 115, 119, 142, 15°-
— Esox:

lucins, 85, 115, 120, 140.

vermiculatus, 105, 115, 142, 156.
— Etheostoma:

coeruleum, 95, 97, 119.

flabellare, 95, 97, 119.

zonale, 95, 97, 119, 120.
— Eucalia inconstans, 85.
■ — Eupomotis gibbosus, 84, 156.
— Fundulus:

diaphanus menona, 84, 123.

dispar, 120, 132, 135.

notatus, 119.
— Hadropterus aspro, 95, 97, 120.
— Hiodon:

alosoides, 85.

tergisus, 85.
— Hybopsis kentuckiensis, 119.
— Labidesthes sicculus, 85, 130, 135.
— Lepisosteus osseus, 85.
— Lepomis:

cyanellus, 102, 119, 120, 128, 156.

megalotis, 99, 119.

pallidus, 84, 99, 115, 119, 120, 156.
— Lota maculosa, 82, 85.
— Microperca punctulata. 84, 119.
— Micropterus:

dolomieu, 85, 99, 119, 120.

salmoides, 85, 115, 120, 128, 156.
— Moxostoma:

aureolum, 84, 115, 119, 140.

breviceps, 120.

356

ANIMAL COMMUNITIES

Fish — Continued:
— Notropis:

atherinoides, 84.

blennius, 84, 119, 127, 135.

cayuga, 115, 119, 140.

cornutus, 115, 119, 120, 140.

hudsonius, 84.

rnbrifrons, 119.

umbratilis, 119, 120.
— Noturus flavus, 119.
— Perca flavescens, 85, 99, 119, 120, 126,

156.
— Percopsis guttatus, 84.
— Phenacobius mirabilis, 119.
— Pimephales:

notatus, 84, 91, 115, 119, 120.

promelas, 115.
— Pomoxis:

annularis, 115, 140.

sparoides, 120.
— Rhinichthys atronasus, 91, 93, 106, in,

US-
— Schilbeodes:

exilis, 95.

gyrinus, 85, 105, 119, 142.
— Semotilus atromaculatus, 91, 106, in,

115, 119, 120.
— Stizostedion vitreum, 85.
— Triglopsis thompsoni, 81.
— Umbra, 65:

/??;«*, 84, 119, 120, 142, 143, 149, 156.
Fisher, 196.

Flat worms: brown cigar-shaped, 174;
green, 176, 179; vernal planarians, 176.
Flatworms, scientific names:
— -Dendrocoelum, 118, 172.
— Mesostoma, 174, 185.
— Planaria:

dorotocephala, 118, 172.

maculata, 135.

velata, 176, 185, 278.
— Vortex, 176, 179:

viridis, 185, 278.
Flesh-flies, 119.
Flicker, 274, 275.
Flies, or diptera, scientific names:
— Anthomyidae, 284.
— Asilus, 285.

— Bibio albipennis, 266, 268.
— •Bombylius major, 232.
— Cecidomyia:

verrucicola, 192.

viticola, 191.

vitis-pomum, 191.
— Chlorops sidphurea, 284.
— Chrysomyia macellaria, 186.
— Chrysops:

aestuans, 188.

callidus, 188.

— Coenomyia ferruginea, 271, 277.

— Coenosia spinosa, 285.

— Cynomyia cadaverina, 186.

— Dasyllis, 270.

— Dolichopodidae, 284, 297.

— Drosophila amoena, 207.

— Drosophilidae, 284.

— .Era*, 224.

— Eristalis tenax, 214, 270, 272, 293, 297,

298.
— Exoprospa, 223, 224.
— Hetobia hybrid a, 272, 277.
— Helophilus conostoma, 285.
— Loxocera pectoralis, 208.
— Mesogramma, 292.

geminata, 297.

marginata, 188, 205.

polita, 292.
— Milesia virginiensis, 259 271, 272.
— Muscidae, 219.
— Mycetophilidae, 217, 247.
— Osinidae, 284.

— Pachyrhina ferruginea, 256, 277, 285.
— Paragus angustifrons, 285.
— Pipunculus fuscus, 280.
— Promachus vertebratus, 222, 224.
— Psilidae, 208.
— Psilopodinus sipho, 270.
— Sapromyza philadelphica, 239, 257.
— Sarcophaga, 186.
— Sarcophagidae, 219.
— Sciara, 217.
— Sciomyzidae, 204, 284.
— Scoliocentra, 279:

helvola, 280.
— Sepedon pusillus, 204.
— Sparnopolius flavins, 285.
— Spilogaster, 281.
— Spilomyia longicornis , 261.
— Spogostylum anale, 229, 230, 234, 252.
— -Straussia longipcnnis, 40, 272, 277.
— Syritta pipiens, 285.
— Syrphus:

americanus, 202.

ribesii, 214.
— Tabanidae, 170.
— Tabanus lineola, 281.
— Tetanocera, 170, 188, 279:

combinata, 188.

plumosa, 188, 197, 284.

saratogensis, 188.

umbrarum, 188, 280, 284, 297.
■ — Tipulidae, 206.
— Tritoxa flexa 285, 297.

Flood-plain communities, 197-204.

Floods: 105; insects in, 203; mammals
in, 202; mixing of communities by,
105; upstream migration during, 106,
107.

INDEX OF SUBJECTS

357

Fly larvae, scientific names:

— Ceratopogon, 148, 155.

— Chironomidae, 103, 187, 191.

— Chironomus, 93, 96, 99, 116, 117, 118,
123, 134, 142.

— Corethra, 125.

— Dixa, 93, 118.

— Metriocnemis, 83, 84.

— Pedicia albivitta, 114.

— Simulium, 87, 88, 93, 105, 114, 116, 118.

— Stratiomyia, 123.

— Tabanus, 116.

—Tanypus, 93, 118, 14S, 155.

Flycatcher: Traill's, 190; great crested,
196, 244.

Food: factor in distribution, 299;
emphasized by paleontologists, 299; of
young fishes, 76, 142, 144; relations:
aquatic, 65-72, terrestrial, 166-68.

Forest communities: 189-261; clay, 210-
17; dry, 209-33; flood-plain, 197-203;
mesophytic, 233-47; rock, 217-18;
swamp, 189-93; sand, 218-33; sum-
mary of, 250-51; tamarack, 193-97;
wet, 189-200.

Forest margin communities, 262-75.

Form, relation to function, 22.

Formations, defined, 38. See Communi-
ties.

Fox: gray, 15, 237, 245; red, 201, 236,
237, 245.

France: bird protection in, 11; Phyl-
loxera in, 191.

Frog: 173; bull, 171; common, 156, 169,
195, 296; cricket, 135, 169, 296; green,
169, 171, 195; swamp tree, 195, 206,
283, 296; tree, 205, 234; tree (Picker-
ing's), 194, 195, 196, 207, 234, 244,
253; wood, 195, 206, 207, 243, 244.

Function, relation to form, 22.

Gall flies, 40, 191, 272, 277.

Gallinule, Florida, 171.

Gar, long-nosed, 85.

Garter-snake, 167.

Gas-bubble disease of fishes, 60.

Geology, surface in young stream, 8.

Gland, silk, 95.

Glen wood beach, 46.

Goldfinch, 268, 274; American, 199, 274.

Gopher, pocket, 167, 288.

Gordius, 101.

Grape: apple gall of, 191; free from

Phylloxera in wet soil, 190; tube gall

of, 191; wart gall of, 191.

Grasshoppers: 167, long-horned, 227;

maritime, 223-25.
Grebe, pied-billed, 132.
Green snake, 289.
Grossbeak, pine, 229.
Ground beetles, 180.
Grouse, ruffed, 196, 227.
Guide to Chicago region, 50.

Habitat: preference, 31; selection, 34.
Hair-worm {Gordius), 101.
Hare, varying, 15, 191, 195.
Harvestmen, scientific names:
— Liobunum:

dorsatum, 202, 205, 208.

grande, 204, 298.

nigropalpi, 244, 253.

ventricosiim, 202, 208.
— Oligolophus pictus, 244, 261.
Hawk: marsh, 167; night, 167, 289; red-
shouldered, 242; red-tailed, 242; sharp-
shinned, 274, 275; sparrow, 274, 275.
Hemiptera (true bugs), aquatic, scientific

names:
— Belo stoma, 65, 131.

americana, 148.
— Belostomidae, 65, 151.
— Benacus, 131.

griseus, 148.
— Buenoa, 132:

platycnemis, 135, 148, 155.
— Corixa, 104, 117, 123, 155.
— Notonecta, 117, 132:

undulata, 135, 148, 155.

variabilis, 123, 135, 148, 155.
— Notonectidae, 151.
— Pelocoris femoratus, 104, 123.
— Plea, 132:

striola, 148, 155.
— Ranatra, 65, 131, 151.

fusca, 104, 123, 155.

kirkaldyi, 155.
— Z ait ha, 65.

fluminea, 104, 116, 123, 135, 148, 155,

185.
Hemiptera, terrestrial, scientific names:
■ — Acanthocephala terminalis, 241, 257.
— Acholla multispinosa, 199, 208.
— Adelphocoris rapidus, 188, 214, 264,

266, 276, 292, 297.
— Agallia 4-punctata, 298.
— Alydus conspersus, 292, 297.
— Amphiscepa bivittata, 188, 199, 208,

292.
— Aphrophora, 202:

4-notata, 267.

358

ANIMAL COMMUNITIES

Hemiptera — Continued:
— Athysanus:

striolus, 297, 298.

parallelus, 297.
— Banasa calm, 261.
— Campylcnchia curvata, 292, 297.
— Cercopidae, 204, 261.
— Ceresa:

borealis, 206.

bubalus, 265, 276, 284, 292.
— Chariesterus antennator, 259.
— Chlorotetlix:

spatulata, 298.

tergata, 297.

unicolor, 297.
— Cicada linnet, 260
— Cicadula:

6-notata, 283, 297.

variata, 206.
— Clastoptera:

obtusa, 261.

proteus, 277.
— Colo p ha ulmicola, 192.
— Corynocoris distinctus, 276.
— Corythuca arcuata, 233.
— Cosmo pepla camifex, 187, 188, 298.
— Cymus angustatus , 188.
— Diedrocephala coccinea, 277.
— Diplodus luridus, 228.
— Draeculacephala mollipes, 188, 283, 297.
— Empoasca malt, 188, 298.
— Enchenopa binotata, 274.
— Euschistus:

fissilis, 264, 276.

tristigmus, 205, 241, 260, 264.

variolarius, 259, 298, 306.
— Eutettix straminea, 298.
— Garganus fusiformis, 298.
— Gargaphia tiliae, 244, 261.
— Gelastocoris oculatus, 180, 185, 186.
— Gypona:

octolineata, 206, 261.

striata, 206.
— Halticus uhleri, 292, 298.
— Helochara communis, 297.
— Horcias:

goniphorus, 292.

marginalis, 298.
— Hyaliodes vitripennis, 41, 234, 235, 260.
— Idiocerus snowi, 208.
— Ilnacora stalii, 277.
— I schnodemus f aliens, 188.
— Jassus olitarius, 261.
— Lepyronia quadrangularis , 204, 208.
— Lygus:

plagiatns, 206.

pratensis, 198, 208, 257, 263, 266,

292, 306.
— Macrosiphum granaria, 290.
— Megamelus marginatus, 277.

— A/zm dolobrata, 292, 297.

— Neides muticus, 263, 276.

— Neuroctenus simplex, 231, 269.

— Nezara hilaris, 199, 208, 257.

— Ormenis pruinosa, 191.

— Otiocerus degeeri, 259.

— Parabolocratus viridis, 188.

— Pelogonus americanus, 204.

— Pemphigus:

imbricator, 244, 245.

po pulicaulis , 225, 258.

vagabundus, 225, 258.
— Pentagramma vittatifrons, 204.
— Pentatomidae, 261.
— Philaronia bilineata, 187.
— Phlepsius irroratus, 259.
— Phylloxera, 190, 243, 273:

caryae-caulis , 260.

vastratrix, 191, 273.
— Phymata erosa fasciata, 187, 264, 276,

293, 297. _
— Physatochila plexa, 188.
— Plagiognathus:

fuscosus, 208.

politus, 298.
— Platymeiopius acutus, 298.
— Podisus maculiventris, 257, 277.
— Poecilocapsus lineatus, 206, 270, 272,

276, 277.
— Protenor belfragei, 276.
— Reduviolus:

annulatus, 208, 260, 202, 239.
/enw, 187, 283.

subcoleoptratus, 217.

coriacea, 296

humilis, 180.
— Saldidae, 180, 219.
— Scaphoideus:

auronitens, 239, 260.

immistus, 206.
— Schizoneura, 273.
— Scolops sulcipes, 263, 265, 276.
— Stictocephala lutea, 297.
— Stiphrosoma stygica, 276.
— Telemona querci (monticola), 259, 233,

234.
— Teratocoris discolor, 297.
— Thyreocoris:

pulicaria, 298.
unicolor, 187.
— Thyreocoris unicolor, 187.
— Trigonotylus ruficornis, 298.
— Triphleps insidiosus, 259, 306.
— Typhlocyba querci bijasciata, 233, 259.
Heron, green, 181, 192.
Herring: lake, 82, 84; toothed, 85.
Hibernation groups: of beetles, 192-93;

of snails, 192; of flood-plain animals,

INDEX OF SUBJECTS

359

History: of Chicago region, 13-15;

geological, 45-48.
Hog-nosed snake, 231.
Hornet, white-faced, hibernation of, 192.
Horntails, 217.
Humus in soil, 158.
Hydra, 107, 131.
Hymenoptera: scientific names:
— A gaposte mo n:

splendens, 232, 259.
viridiilus, 297.
— Ammophila. 231:
nigricans, 285.
procera, 231.
— Andrenidae, 224, 255.
— Andricus seminator, 234, 260.
— Anomoglossus pusillus, 188.
— Anoplius:

divisus, 222, 252.
marginatus, 255.
— Apidae, 224.
— Apis mellifera, 214.
— Augochlora:

confusa, 187, 252.
pura, 239, 256.
— Bembex spinolae, 222, 223, 252.
— Bombus:

americanorum, 214.
separatus, 290, 297
— Ceropalidae, 255.
— Chloralictus cressoni, 277.
— Cimbex americana, 208, 267.
— Coeloixys rufitarsus, 231, 255.
— Crabro interruptulus, 277.
— Dielis plumipes, 222, 252.
— Epeolus:

cress onii, 285.
pusillus, 231, 253.
— Eumenes jraternus, 266, 276.
— Eumenidae, 255.
— Halictus nelumbonis, 255.
— Ichneumon:

extrematatus, 192.
galenus, 192, 297.
mendax, 191, 192.
zebratus, 285.
— Ichneumonidae, 261.
— Larridae, 255.
— Microbembex, 223:

monodonta, 222, 223, 252.
— Mutilla ornativentris, 222, 252.
— Nematinae, 205.
— Odynerus:

anormis, 231, 255.
tigris, 276.
— Paniscus gemminatus, 285.
— Pelopoeus cementarius, 214, 254.
— Pimpla:

conquisiwr, 214.
inquisitor, 191.

— Plesia inter rupta, 255.
— Polistes, 241, 266:

variatus, 276, 297.
— Pteronus ventralis, 667.
— Scelipron cementarius, 285.
— Scoliidae, 255.
— Specodes dichroa, 231, 252.
— Tachytes texanus, 255.
— Thalessa atrata, 261.
— Trogus vulpinus, 261.
— Tiphia vulgaris, 286, 289, 290.
— Vespa maculata, 192, 202, 256.
— Xiphydria maculata, 207.

Ice-sheet: Wisconsin, 45; advance and
retreat, 43-46; drainage from, 45,
46.

Indians, 13.

Insects: carriers of disease, 21; enemies
of, 9, 10; human food, 21.

Inter-mores physiology, 34, 35.

Inter-physiology, 34, 35.

Isle Royale, 195.

Isopods. See Sowbugs.

Lacebugs, 232.

Lake: Chicago, 45-47; Geneva, 62-63;
Michigan, area, 73, bottom communi-
ties, 78-81, communities, 73-85, condi-
tions, 58-65, light, 63, pressure, 64,
temperature, 62, species, 83-85; On-
tario, 78; Pine, 67; Turkey, 67.

Lake communities, 73-85, 124-36; sum-
mary concerning, large lake, 81, small
lake, 128, 131.

Lake herring, 77.

Lakes: circulation in, 60; distinguished

from ponds, 124.
Lampreys, 219.
Larch or tamarack: sawfly, 195; lappet

moth, 195; woolly aphid, 195.
Lark: bunting, 286, 289; horned, 167,

289; meadow, 167, 283, 289; shore,

286.
Larvae: lepidopterous, 167; sawfly, 167.
Laws: minimum, 68; toleration, 302;

limit of range, 304; distribution area,

304.
Lawyer, 82, 85.
Leaf-beetles, long-horned aquatic, 65,

123, 135, i5i-
Leaf -bugs, hibernating, 202.
Leeches: in Lake Michigan, 77, 80, 8^,

84; in lakes and ponds, 129; in

streams, 101, 103.

3 6 °

ANIMAL COMMUNITIES

Leeches, scientific names:

— Clepsine, 84.

— Dina fervida, 153.

— Erpobdclla punctata, 153.

— Glossiphonia:

fusca, 123, 153.

heteroclita, 153.

stagnalis, 83.
— Eaemopis:

grand is, 103, 121, 153.

marmoratis, 153.
— Macrobdella decora, 135, 151, 153.
— Placobdella:

parasitica, 135, 148, 150, 153.

rugosa, 117, 153.
Lepidoptera, scientific names:
— Acronycta oblinita, 188, 267.
— Agrotis ypsilon, 285.
— Alypia octomaculata, 273.
— Ampelophagus myron, 268.
— Anisota senatoria, 241, 260.
— Anthocharis genutia, 257.
— Apantesis phalterta, 285.
— Basilarchia archippus, 251.
— Cerura, 232, 259, 279.
— Datana, 199:

angusii, 260.
— Diacrisia virginica, 285.
— Estigmena acraea, 284, 285.
— Evetria comstockiana, 228, 229, 258.
— Geometridae, 205.
— Halisidota, 238, 260.
—Hemileuca maia, 188, 268, 276.
— Heterocampa guttivitta, 259.
— Hydria undidata, 260.
— /sia Isabella, 285.
— Leucania unipuncta, 285.
— Nadata gibbosa, 231, 233, 259.
— Noctuinae, 204.
— Papilio:

ajax, 244.

cresphontes, 268, 276.

troilus, 244.
— Pieris protodice, 220, 222.
— Prionoxystus robiniac, 267.
— Psychomorpha epimensis, 273.
— Pyrameis:

hunter a, 270.

cardui, 270.
— Samia cecropia, 199.
— Scepsis fulvicollis, 170, 284, 297.
— Schizura, 268.
— Symmerista, 199:

albifrons, 200, 260.
Licenses to collect animals, 57.
Liebig's law of minimum, 68.
Life histories: physiological, 33; repre-
sented as circles, 71.

Light: intensity, 159-60; necessity for

food supply, 66; penetration in water,

63; reactions to, 29, 251.
Limnetic communities, 74-7 7, 103, 125,

140.
Living substance, 22.
Lizard, six-lined, 227.
Localities studied, 52-56.
Locust: lesser, 227; long-horned, 227;

lubbery, 262; mottled sand, 227;

narrow- winged, 227; sand, 227.
Logs: lake, 131; in ponds, 150; in

streams, 101.
Long- jaw, 79, 80, 82, 85.

Maggots, 219.

Mallard, 171.

Mammalia, 2.

Mammals, economic value of, 9, 10.

Mammals, scientific names:

— Bison bison, 289.

— Blarina brevicauda, 201.

— Cams latrans, 286.

— Citellus:

franklini, 269.

13-lineatus, 228, 255, 286.
— Fiber zibethicus, 156.
— Geomys bursarius, 288.
— Hominidae, 2.
— Homo sapiens, 2, 319.
— Lepus americanus, 191, 195.
— Lutra canadensis, 195, 199.
— Lynx rufus, 242.
— Marmota monax, 215, 253.
— Maries:

americana, 196.

pennanti, 196.
— Mephitis mesomelas avia, 269.
— Microtus:

ochrogaster, 289.

pennsylvanicus, 282.
— Mustela:

noveboracensis, 201.

vison lutreocephala, 191.
— Odocoileus virginianus, 238.
— Peromyscus:

bairdii, 286.

leucopus noveboracensis, 201, 236.
— Primates, 2.

— Sorex personatns, 189, 201, 275, 269.
■ — Tamias striatus griseus, 269.
■ — Taxidea taxus, 288.
— Urocyon cinereoargentens, 237.
— Vulpes fulvus, 236.
— Zapus hudsonius, 269.
Man, relation to animals, 5-20.

INDEX OF SUBJECTS

361

Maps: evaporation, 50; frontispiece, ii;
guide, (facing) 52; list of, 48; vegeta-
tion, 51.

Marsh communities, 169-73.

Marten, pine, 196.

Materials for abode, of land animals,
157.

May-flies, 65, 170.

May-flies or Ephemerida, scientific names:

— Baetis, 93.

— Caenis, 114, 123, 155.

—Callibaetis, 104, 123, 130, 135, 155.

— Chirotenetes siccus, 117.

— Ephemerella excrucians, 135.

— Ephemeridae, 78.

— Heptagenia, 93, 118.

— Heptageninae, 96, 105, 114.

— Hexagenia, 39, 103, 107, 117, 123.

— Siphlurus, 96, 142, 155:
alternatus, 98, 116.

May-fly nymphs, 88.

Metallic wood-borers, 191.

Methane, 59, 60.

Midge larvae: 69, 80, 129, 130; an-
aerobic, 133. See Fly larvae.

Midges, 170.

Miller's thumb, 126.

Mimicry, 25.

Mineral matter: excessive in springs
93; necessary to life, 58.

Mink, 15, 171, 191.

Minnow: blackfin, 119, 120; black-
head, 115; blunt-nosed, 79, 84, 115,
119, 120, 126; Cayuga, 115, 119, 140;
mud, 65, 84, 119, 120, 143, 149, 156;
ruby faced, 119; shiner, 84; straw-
colored, 79, 84, 126, 127, 135; sucker-
mouthed, 119.

Mites, aquatic, egg-laying of, 129.

Mites, aquatic, scientific names:

— Hydrachna, 177, 185.

— Limnochares aquations, 130, 144.

Mites, terrestrial, scientific names:

— Trombidium, 190:
sericeum, 207.

Moisture: equivalent of soil, 158; re-
lation to wilting coefficient, 158.

Mole cricket, 181.

Moles: 167, 238; star-nosed, 282.

Mollusca, 80, 106, 144. See Snails;
Mussels; Sphaeridae.

Moon, influence of, on plankton, 67.

Moon-eye, 85.

Mores, defined, 32.

Mosquito: eaten by fishes, 132; fringe-
legged, 174; marsh, 174, 176; smoky,
178, 180.
Mosquitoes, scientific names:
— Aedes fusca, 178.
—Anopheles, 114:

punctipennis , 176.
— Culex canadensis, 193, 206.
— Culicidae, 185, 191.
— Wyeomyia smithii, 193, 204.
Mourning dove, 269, 274, 275.
Mouse: Cooper's lemming, 195; deer,
167; field, 167, 289; food of marten,
196, of skunk, 269, of shrews, 269;
meadow, 282; white-footed wood,
201, 237; jumping, 269, 274.
Mud puppy, 130.
Muskrat, 14, 130, 156, 140, 143, 151,

171.
Mussels: 70; stunted on humus, 129.
Mussels, scientific names:
— Alasmidonta calceola, 99, 100, 116, 121.
— Anodonta:

grandis, 83, 103, 104, 126, 153.

grandis footiana, 143, 153.

marginata, 83, 126, 135, 140, 153.
— Anodontoides:

ferussacianus, 39, 99, 100, 108, 117,

127.

ferussacianus subcylindraceus , 100.
— Lampsilis:

ellipsiformis , 117, 121.

iris, 117.

ligamentina, 99, 117, 123.

luteola, 99, 103, 117, 121, 122, 123,

126, 129, 135, 140, 153.

ventricosa, 99, 117, 122.
— Quadrula:

rubiginosa, 103, 117, 122, 123.

undulata, 103, 117, 121, 122, 123.
-TJnio gibbosus, 103, 117, 122, 123.
— Unionidae, 146, 153
• — Symphynota:

complanata, 122.

costata, 122.

Myriopods, viii, 215.

Myriopoda, scientific names:

— Fontaria corrugate, 215, 236, 237, 243,

253, 254.
— Geophilus, 200, 254.

rubens, 217, 239, 243, 253.
— Lithobius, 187, 191, 234, 239, 254.
— Lysiopetalum lactarium, 217, 239, 253

254.
— Polydesmidae, 215.
— Polydesmus, 191, 205, 206, 234.
■ — Scytonotus granulatus, 206.

3 62

ANIMAL COMMUNITIES

Myriopoda — Continued:

— Spirobolus marginatus, 201, 236, 237,

243, 2 53-
My sis r dicta, 80, 81, 85.

Natural selection, 25.
Nature: 5, 6; man and, 8-20; man-
made, 8; state of, 7; struggle in, 7.
Neuroptcra, scientific names:
— Chauliodes, 123.

rastricornis, 145, 148, 150, 155.
— Chrysopa:

albicornis, 297.

oculata, 214, 291.

rujialbris, 261.
— Corydalis cornuta, 116, 121.
— Cryptoleon nebulosurn, 283.
— Mantis pa brunnea, 273, 274.
— Sialis, 121.
Newt, 121, 149, 156.
Nitrates, 66.

Nitrogen: 59, 60; cause of gas-bubble
disease, 60; in lakes, 125; in spring
water, 93.

Number of individuals, relation to area
of optimum, 303.

Onion- fly, 293.

Optimum, range of, 300-305.

Oriole: Baltimore, 274, 275; orchard,

274.
Orthoptera, 243, 272, 285, 292, 306.
Orthoptera, scientific names:
— Acrididae, 187, 204.
— Ageneotettix arenosus, 227, 252.
— Amblycorypha, 205:

oblongifolia, 208, 266, 267, 276.

rotundifolia, 272.

uhleri, 241.
— Apilhes agitator, 268.
— Apterygida aculeata, 194, 205.
— Atlanticus pachymerus, 239, 260.
— Ceuthophilus, 205, 237, 239, 243.
— Chloealtis conspersa, 232, 259.
— Conocephalus:

ensiger, 232, 259, 298.

nebrascensis , 264, 276.

robustus, 265.
— Cyrtophillus perspicillatus, 241, 260.
— Diapheromera femorata, 187, 235, 241,

257.
— Dissosteira Carolina, 198, 214, 218, 254.
— Gryllus pennsylvanicus, 218.
— Hippiscus tuber culatus , 255.
— Ischnoptera:

inaequalis, 218.

major, 218.

— Melanoplus:

angustipennis, 227, 252.

atlanis, 225, 228, 252.

bivittatus, 198, 218, 276, 285, 297.

dijferentialis, 266, 276.

femur-rubrum, 187, 214, 218, 223,

276, 285, 296.

punctulatus, 194, 195, 205.

viridipes, 297.
— Nemobius:

fasciatus vittatus, 298.

maculatus, 263, 297.
— Neotettix hancocki, 190.
— Oecanthus:

angustipennis, 241, 260, 272.

fasciatus, 232, 257, 272, 276.

nivens, 272.
— Orchelimum:

glaberrimum, 204, 208.

indianense, 276.

vulgare, 292, 296, 298.
— Orphulella speciosa, 297.
— Paratettix cucullatus, 181, 186.
— Paroxya hoosieri, 204.
— Psinidia fenestralis, 223, 225, 252.
— Schistocerca rubiginosa, 232, 257.
— Scudderia, 214, 217:

furcata, 241, 266, 267, 276.

texensis, 232, 259, 266, 277, 293,

297, 298.
— Sparagemon wyomingianum, 228, 252.
■ — -Sienobothrus, 170:

curtipennis, 188, 204, 266, 285, 296,

298.
—Tettigidea:

armata, 181.

parvipennis, 181, 282.

pennata, 236, 282.
— Tettix obscura, 190.
— Trimerotropis maritima, 223, 252.
— Xiphidium, 1 70 :

brevipenne, 188, 208, 263, 266

ensiferum, 215.

fasciatum, 39, 188, 263, 264, 284,

285, 296.

nigropleura, 263, 276.

strictum, 232, 259, 292, 293, 298.
Osprey, 226.
Ostracods, 129.

Ostracods or Ostracoda, scientific names:
— Cypria exsculpta, 152.
— Cypridopsis vidua, 130, 152.
— Cypris fuscata, 185.
— Cyprois marginata, 177, 179, 185.
— Notodromas monacha, 144.
■ — Ostracoda, 144.
—Potamocypris smaragdina, 134.
Otter, 195, 199.
Oven-bird, 244.

INDEX OF SUBJECTS

36;

Owl, screech, 229.

Oxygen: anaerobic animals, 133; bur-
rowing dragon-fly nymphs, 142; circu-
lation of, 61; correlated with age of
ponds, 68-70; in lakes, 125, 133; in
pools, 91; in springs, 93; in streams,
103; intermittent quantities, 90; neces-
sary in water, 59; not added by certain
plants, 65; reduced by sewage, 17.

Panther, 15, 238, 242.

Partridge, 196.

Perch: pirate, 120; yellow or American,
85, 99, 119, 120, 126, 130, 156; trout-
perch, 84.

Pest species, number of, on different
forest trees, 166.

Pewee, wood, 242, 244.

Phalangids, 167.

Physiological agreement of communities:
34; life histories, $^; proportionality
in organisms, 26.

Physiological equilibrium: 26; distrib-
uted by changes in the organism, 30,
by external conditions, 30; in relation
to habitat, 31.

Pickerel, grass, 105, 115, 142, 156.

Pike: 85, 115, 120, 140; pike-perch, 85;
wall-eyed, 85.

Pintail, 171.

Planarians, in Lake Michigan, 77.

Plankton: in arctic seas, 66; proportion
to denitrification, 66; relation to tem-
perature, 66, to C0 2 , 67, 68, to oxygen,

67, 68, to carbonates, 67, 68, to rate of
flow, 67, to seasons, 67, to age of ponds,

68, to moon, 67.

Plants, aquatic: in sandy riffles, 99; in
sluggish streams, 104; value of, to
animals, 65, 142; watercress, 93.

Plants, aquatic, scientific names:

— Chara, 64, 65, 74, 142, 145, 148.

— Cladophora, 64, 74.

— Elodea, 65, 129.

— Equisetum, 65, 151.

— Myriophyllicm, 65, 129, 130, 131, 145.

— Nostoc, 74.

— Potamogeton, 145.

— Proserpinaca, 151.

Plants, terrestrial, scientific names:

— Arabis lyrata, 228.

— Citrus, 257.

— Gossypium, 257.

— Hibiscus, 189.

— J uncus balticus, 173.

— Monarda, 228, 232.

— Opuntia, 255.

— Pamassia caroliniana, 182.

— Pinus banksiana, 228.

■ — Sagittaria, 175.

■ — Tilia, 257.

Plover, piping, 180.

Polyzoa, scientific names:

— Fredericella sultana, 84.

— Paludicella ehrenbergii, 84.

— Pectinatclla magnifica, 128, 130, 135.

— Plumatella, 84, 103, 121, 131:
polymorpha, 135.

Polyzoan, gelatin-secreting, 128, 129.

Pond animals in streams, 102, 103.

Pond communities: 136-57; temporary,
173-80.

Ponds, vernal or temporary: forest, 179;
snails of, 192; influence of rainfall on,
177-79; vegetation choked, 174; young,
with bare bottom, 173.

Porcupine, Canada, 196.

Prairie chicken, 167, 289.

Prairie communities, 278-98.

Pressure of water, 64.

Protected situation of large lake, com-
munities of, 80.

Protection of wild animals: 8-1 1; pro-
tected species, 56, 57; wardens, 57.

Proteid, foodstuffs, 66.

Protozoa: 129, 130; anaerobic, 133;
as animal food, 20; producers of disease,
20.

Protozoa, scientific names:

— Actinophrys sol, 75.

■ — Difflugia:

globulosa, 75.
pyriformis, 132.

— Peridinium tabulatum, 75.

Psocus, 234.

Pulmonate snails, aquatic respiration
of, 129.

Pumpkin-seed, 84, 156.

Puss caterpillar, behavior of, 232.

Quantity: of larger animals, 69; of life
on land, 166; of plankton: causes of
fluctuations in, 72; in different bodies
of water, 67; in ponds of different
ages, 69; in polar regions, 66; seasonal
variation in, 67.

Rabbit: 196; cottontail, 269, 275.
Raccoon: 199, 202; eats crayfishes, 90.

3 6 4

ANIMAL COMMUNITIES

Rail: king, 171; sora, 171; Virginia, 171.
Rapids: communities of intermittent,

87; formation of, 94-99.
Rattlesnake, 167.
Reactions: defined, 26; positive and

negative, 26; to current, 34, 9 1 , 95,

101, 106, 107.
Red-legged locust, 266.
Redstart, 274, 275.
Regulation in behavior, 29.
Rejuvenation of streams, 108.
Relations of communities, 308-15.
Reptiles: economic value of, 10, 21; in

timber and prairie, 15.
Reptiles, scientific names:
■ — Cnemidophorus 6-lineatus, 227, 252.
■ — Coluber constrictor, 255.
— Crotalus durissus, 237.
— Heterodon platirhinos, 255.
— Liopeltis vernalis, 289, 299.
— Sistrurus catenatus, 204, 289.
— Thamnophis, 150:

radix, 283, 288, 296.
— Tropidonotus grahamii, 283.
Responses, to day and night, to weather,

to seasonal changes, 31.
Rheotaxis: Allee on, 327; Lyon on, 101;

of fishes, 34, 91, 92, 95, 101 ; of isopods,

92; of mollusks, 106, 107; of stream

animals, 91, 101.
Rivers, drowned and sluggish, 102, 103.
Roadsides, 13, 275.
Rotifers: 65; diurnal migration of, 77;

of Lake Michigan, 75-77; sessile, 131.
Rotifers, scientific names:
■ — Dinocharis tekactis, 84.
— Notops:^

pelagicus, 76.
pygmaeus, 77.
■ — Rotifer elongatus, 84.
Roundworms, in Lake Michigan, 77.

Salamanders: four-toed, 237; spotted,
149, 278, 282, 296; sticky, 181, 183,
207; red-backed, 197, 243, 255.

Sandpiper, spotted, 180, 181.

Scorpion- flies, 202.

Scorpion- flies, scientific names:

— Bittacus, 202:
strigosus, 208.

— Panorpa, 40, 191 :
venosa, 200, 208.

Seasons: Relation of animals to, 31;
succession with, 36, 278; quantity of
plankton in, 67.

Sediment, in water, relation to light pene-
tration, 63.
Seeds, as animal food, 167.
Segregation of species, vertical in Lake

Michigan, 82.
Seines, illegal, 57.
Selection of habitat: 300-305; law of

toleration in, 302-5.
Sessile animals, food of: 97; in sea, 309;

motile animals compared with, 309.
Sewage, effect of: upon stream animals,

17; upon oxygen content, 17; upon

plankton, 17.
Sheepshead, 85.
Shiner: 79, 84; common, 115, 119, 120,

140; golden, 65, 102, 115, 119, 120, 142,

143, 156.
Shore-bugs, 180.
Shores, sandy: of large lakes, 78; of

small lakes, 125, 126.
Shrew: common, 189, 191, 196, 201, 262,

269, 274; short-tailed, 201.
Shrike, loggerhead, 275.
Shrimps, scientific names:
— Eubranchipus, 177, 178, 179, 278:

serratus, 185, 279.
— Palaemonetes paludosus, 126, 130, 135,

152.
Silversides, 85, 130, 135.
Skunk, 12, 15, 169, 199, 262, 274.
Slug caterpillar, 233.
Slugs, scientific names:
— Agriolimax campestris, 199, 200, 202,

205, 236.
— Pallifera dor salts, 256.
— Philomycus Caroline nsis, 206, 215, 240,

241, 243, 247, 253, 254.
Smeared dagger-moth, larva of, 190.
Snails: aquatic, 90; in lakes, 130; reac-
tions of, to light, 29; reactions of, to

water current, 34.
Snails, aquatic, scientific names:
— Amnicola, 80, 148:

cincinnatiensis, 117, 154.
emarginata, 83.

limosa, 83, 99, 117, 121, 145, 146, 154.
limosa parva, 154.
limosa porata, 83.
lustrica, 83.
walkeri, 84.
— Ancylus, 130:
fuscus, 135.
rivularis, 121.
tardus, 121.
— Aplexa hypnorum, 192.

INDEX OF SUBJECTS

365

Snails — Continued:

— Campeloma, 99, 103, 104, 106:

integrum, 107, 108, 117, 123.

subsoliduni, 100, 117.
— Goniobasis, 103:

livescens, 95, 98, 103, 116, 121, 123,

126, 135.
— Lymnaea, 84, 104, 131, 145:

exigua, 173, 185.

lanceata, 85.

modicella, 114, 121, 154, 174, 181,

186, 187.

obrussa, 154.

reflexa, 147, 149, 154, 174, i75i 185,

189.

reflexa exilis, 154.

stagnalis, 83.

woodruffi. 79, 80, 84.
—Physa, 1 45-151:

gyrina, 93, 114, 118, 121, 131, 135,

154, 173, 185.

heterostropha, 154, 173.

integra, 104, 117, 131.
— Planorbis, 173, 185.

bicarinatus, 39, 83, 99, 104, 117, 121,

123, 154.

campanulatus , 114, 131, 135, 147, 149,

154.

deflectus, 154.

exacuosus, 154.

exacutus, 83.

hirsutus, 148, 149, 154.

parvus, 116, 131, 135, 148, 149, 154,

204.

trivohis, 16, 149, 150, 152, 154.
— Pleurocera, 99, 103:

elevatum, 106, 107, 108, 121, 123.

elevatum lewisii, 117.

subulate, 39, 126, 127, 135.

subulate internum, 121.
— Pleuroceridae, 84.
— Segmentina armigera, 131, 135, 154.
— Valvata, 80:

bicarinata perdepressa, 83.

s nicer a, 83.

tricarinata, 83.
— Vivipara contectoides , 126, 128, 152.
Snails, hibernation of, 192.
Snails, terrestrial, scientific names:
— Circinaria concava, 200, 204, 206, 237.

253.
— Omphalina fuliginosa, 2 53 .
— Polygyra:

albolabris, 197, 207, 215, 237, 243, 254.

clausa, 200.

fraudulenta, 243, 256.

inflecta, 234, 256.

monodon, 190, 213, 215, 254, 263.

multilineata, 206, 234.

oppressa, 243, 256.

palliata, 243, 256.

pennsylvanica, 236, 237.

profunda, 200, 202, 215, 236, 237.

thyroides, 200, 202, 208, 213, 215,

234, 252, 254.
— Pyramidida, 214, 215, 243:

alternata, 192, 200, 236, 237, 243, 247,

253, 254.

perspectiva, 256.

soHtaria, 236, 237, 243, 256.

striatella, 190.
— Succinea:

avara, 187, 199, 202, 208, 282.

ovalis, 208, 263, 264.

retusa, 169, 187, 189, 199, 202, 204,

208.
— Vitrea indentata, 205.
— Zonitoides, 215:

arboreus, 190, 206, 234, 236, 243, 247,

253, 306.
Snakes, food of skunks, 269.
Soil: 157-59; effect of, on organisms
159; factor in distribution, 301,
humus, 158-59.

Sowbugs or Isopoda, aquatic, scientific

names:
■ — Asellus communis, 90, 98, 114, 121,

154, 174, 185, 206.
■ — Mancasellus danielsi, 135, 154, 174.
Sowbugs, terrestrial, scientific names:
— Cylisticus convexus, 239, 253.
■ — Porcellio rathkei, 200, 240, 254, 253.
Sparrow: chipping, 274, 275; field, 274,
275; grasshopper, 167, 289; lark, 275;
song, 262, 268, 275; vesper, 167.
Sparrow-hawk, 274.
Species, animal: 1; number of, 1; plant,

1; use in ecology, 3.
Sphaeridae, scientific names:
— Calyculina transversa, 83.
— Musculium, 118, 179, 189.

partumeium, 147, 153.

secure, 147, 153, 185.

truncatum, 121, 147, 153.
— Pisidium, 81:

compression, 83.

idahoense, 83, 133.

punctatum, 83.

scutellatum, 83.

variabile, 83.

ventricosum, 83.
— Sphaeridae, 69, 80, 83, 100, 103, 147,

I5 1 , 153-
— Sphaerium, 108:

stamincum, 107, 116, 121.
striatininn, 80, 83, 116.
vermontanum, 79, 84.

3 66

ANIMAL COMMUNITIES

Spherid, anaerobic, 133.
Spiders, 167.
Spiders, scientific names:
— Acrosomal

gracilis, 238, 240, 260.

spinea, 238, 240, 260.
— Agelena naevia, 207, 218, 254, 296.
— Anyphaena conspersa, 260.
— Argiope:

aurantia, 263, 264, 276, 296.

trifasciata, 204, 205, 208, 232, 259,

263, 293, 296, 298.
— Attus palustris, 276.
— Atypus milberti, 277.
— Castianeira cingulata, 197, 207.
— Chiracanthium inclusa, 187, 205.
— Clubiona obesa, 277.
— Dendryphantes:

militaris, 205, 206.

octavus, 204, 205, 206, 228, 258.
— Dictyna:

foliacea, 206, 208, 228, 232, 257, 276.

sublata, 187, 204, 207.
— Dictynidae, 257.
— Dolomedes:

sexpunctatus, 146, 169, 187, 283, 296.

tenebrosus, 243.
— Epeira, 198, 232:

domicilorum, 240, 257, 306.

foliata, 187, 204, 206.

gigas, 194, 205, 206, 208, 240, 257, 272.

ocellata, 206.

prompta, 204.

trifolium, 205, 276, 277, 296.

trivittata, 188, 205, 214, 276, 284, 293,

296.
— Epeiridae, 208, 257, 260.
— Eucta caudata, 187.
— Eugnatha straminea, 204, 296.
— Gayenna celer, 260.
— Geolycosa pikei, 220, 227, 230, 250, 252.
— Habrocestum pidex, 206.
— Hypselistes florens, 207.
— Leucauge hortorum, 202, 208.
— Linyphia phrygiana, 260.
— -Lycosidae. 261.
— Maevia niger, 260, 277, 298.
— Mangora maculata, 206, 260.
— Misumena vatia, 214, 264, 285, 296.
— Misumessus:

asperatus, 231, 232, 257, 293.

oblongns, 207.
— Notionella inter pres, 261.
— Ozyptila conspurcata, 296.
— Pardosa, 215:

lapidicina, 213, 214, 215. 254.
— Phidippus:

audax, 207, 264.

borealis, 297.

podagrosus, 204, 293, 298.

rufus, 298.
— Philodromus:

alaskensis, 223, 228, 257.

ornatus, 205.

pemix, 259.
— Pirata:

insularis, 187.

montana, 204.

piratica, 206.
— Pisauridae, 204
— Pisaurina, 198:

undata, 204, 206, 208, 277.
— Plectana stellata, 204.
— Runcinia aleatoria, 204, 214, 277, 293,

296.
— 5i;?ga variabilis, 276.
— Tetragnatha:

grallator, 205, 206.

laboriosa, 169, 187, 208, 263, 276,

284, 285, 296.
— Theridiidae, 257.
— Theridium:

frondenm, 191, 202, 206, 208, 240,

257, 258.

spirale, 228, 258.
■ — Thiodina puerpera, 204.
— Thomisidae, 257.
— Tibellus didtoni, 187, 204.
— Trochosa cinerea, 222, 252.
— PFa/a mitrata, 261.
— Xysticus formosus, 228, 258.
— Zygoballus bettini, 206.
Spittle insects, habits of, 202.
Sponge, abundant in stream, 97.
Sponges, scientific names:
— Heteromeyenia ar gyros perma, 153.
— Meyenia:

crateriformis, 153.

fluviatilis, 153.
— Spongilla, 116, 131:

fragilis, 153.
Spontaneous movement, 26.
Springtails, 180.

Squirrels: 233; fox, 245; Franklin
ground, 269, 274; gray, 192, 202, 245;
ground, 167, 227, 286; red, 245.
Stations of study, 50, 51-56.
Statoblast, 129.
Stickleback, 85.
Stimulus, defined, 26.
Stinkbugs, hibernating, 202.
Stonecat: 119; slender, 95.
Stone-fly nymphs, scientific name:
— Perla, 78, 116, 121.
Stone-roller, 119, 120.

INDEX OF SUBJECTS

367

Stones: in water, 78, 88, 95-97; currents
about, 61.

Strata: denned, 37; in aquatic vegetation,
105; in rapids, 94-96; on land, 165.

Stream communities: 78, 86-123; base-
level, 102-5; intermittent, 87-92;
longitudinal arrangement of, 108-23;
sandy, 101-2; sluggish, 102-5; spring-
fed, 93; swift, 93-99.

Struggle for existence, 5-6.

Sturgeon, 85.

Succession: autoproductive, 308; causes,
308; denned, 36; ecological, 36;
forest, 247-50; geological, 36; lake,
135; pond, 152; seasonal, 35, 36,
278; stream, 1 10-13.

Sucker: carp, 85; chub, 115, 119, 142,
156; common, 84, 91, 92, 106, 115,
119, 120; long-nosed, 84; hog or stone-
roller, 84, 119; red-horse, 84, 115, 119,
140; short-headed red-horse, 120.

Sunfish: bluegill, 84, 99, 115, 119, 120,
126, 156, 141; blue-spotted or green,
102, 119, 120, 126, 128, 156, 141;
long-eared, 99, 119; pumpkin-seed,
126, 156, 141.

Swallow: bank, 222; tree, 225.

Swamp communities, 169-73, 189-97.

Tadpole catfish, 85, 105, 119, 142.

Tamarack swamp communities, 193-97.

Tanager, scarlet, 244.

Taxis, 26, 27.

Temperature: of soil, 158-59; habitat

compared, 159; control of distribution,

199-304.
Temporary ponds, 173-80.
Tension lines between land and water,

169-88.
Terminology of ecology, 36-38.
Termites, 220-22.
Termites, scientific name:
— Termes flavipes, 220, 252.
Tern, black, 170.

Terrestrial conditions, 169-88, 247-50.
Thicket communities, 262-75.
Thrush: hermit, 195; wood, 241, 244.
Thysanoptera, 306.
Tiger-beetles, 180, 216; larvae, 210, 214,

216.
Toad: 167, 187, 283, 296; daily habits,

222.
Toadbug, 180.

Toleration, law of, 302-5.
Tolleston beach, 47.
Top minnow, 84, 120, 123, 132, 135.
Toxic substances, in soil, 159; in water,
331 (114, 114a).

Transparent animals, 77.

Tree-fauna, differs with surrounding

conditions, 16, 251.
Trespass laws, 56.
Tropism, 26, 27.

Trout, Mackinaw or Lake, 59, 78, 79,
80, 82, 85.

Turkey, wild, 14.

Turtles: geographic, 130, 135, 156;
habits of, 130; musk, 126, 130, 135,
142, 156, breeding of, 130; painted.
132, 156, 227; protected by law, 57;
snapping, 132; soft-shelled, 130; trans-
portation of animals by, 173.

Turtles, scientific names:

— Aromochelys odorata, 126, 135, 142,

— Aspidonedes spmifer, 130.

— Chrysemys marginata, 132, 156, 227

— Graptemys geographicus, 130, 135, 156.

Upstream migration: of fishes, 106; of
mollusks, 106.

Valparaiso Moraine, 46.

Variation of behavior and habits related

to conditions, 34.
Varying hare, 15, 191, 195.
Vegetation: aquatic, 65 (See Plants);

climatic, 49, 50, 51, 174.
Vernal fauna, 173-80.
Vertebrata, 2.

Vertebrates, products from, 21.
Vireo, red-eyed, 196, 244.

Warbler: black, 241; blackbumian, 196;

black-throated, 229; green, 229; pine,

229; prothonotory, 190, 191; yellow,

196, 241, 274, 275.
Water in soil, 157-58.
Water margin communities: 180-83;

sedge-covered, 181; shrub-covered,

181; terrigenous, of large lakes, 180,

of ponds, 180, of rivers, 181.
Water scavenger beetles, 65.
Water- scorpions, 65, 104, 123, 131, 151,

i55.
Water- striders: 90; hibernation of, 201.

;

368

ANIMAL COMMUNITIES

Water-striders, scientific names:

— Gerridae, 185.

— Gerris:

marginatus, 155.
rufoscutellatus, 155.

— Mesovelia bisignata, 155.

— Rhagovelia collar is > 98, 117.

Weasel, 201.

Weeds, avoided by aquatic animals
during flood, 105.

Weevils, 167.

Wheel animalcules. See Rotifers.

Whitefish: 76, 77, 82, 85; blackfin, 81,
82; Hoy's, 81, 82, 85; long-jaw, 79,
80. 82, 85.

Willow blossoms, visited by pollen-
gathering insects, 224-25.

Willow sawfly: large, 267; spotted, 267.

Wildcat, 242.

Wilting coefficient of soil, 158.

Wind: influence on circulation in lakes,
61; relation to light penetration, 63,
to evaporation, 160, 162, 163.

Wolf, 15, 167, 201, 236, 238, 245.

Wood pewee, 196, 244.

Wood thrush, 241.

Woodchuck, 215, 233, 236.

Woodcock, 189, 191.

Wood-frog, 244.

Woodpeckers: 196, 274; downy, 229;
in beach drift, 219; red-headed, 242.

Worms: flat, 20; round, 20.

Wren: long-billed marsh, 171; short-
billed marsh, 181.

Yellowlegs, 181.

Yellowthroat, northern, 189, 262, 275.

Zonation in forest edge, 263.

FprintedI

U_IN USA J

Bl