Bird friends : a complete bird book for Americans

Front matter

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FOR:AMERICANS

Preface

THESE pages are written, not only for the bird-lover, but also for the general reader who has no special interest in birds, but who is interested in those matters that pertain to community welfare. Most of the topics presented in this book have been treated in an entertaining way in many excel- | lent bird books, but most of these books cover only one or two phases of bird life, so that a person desiring to be generally informed on birds must secure several books. The bird enthusiast is glad to do this, but not the average citizen, who has no more interest in birds than in many other topics. It is highly desirable that every citizen should be informed on the need of conserving bird life as one of our valuable national resources. It has been the purpose of the author to gather within one set of covers a brief discussion of the essential facts concerning bird life that are of general interest, which are now scattered through many books, bulletins, and magazines. One of the most interesting developments of the past few years has been the rapid strides made in the cause of bird-protection. Much of this work has been of such recent origin that information regard-

Vill PREFACE ing these various protective agencies and their work can be found only in recent periodicals. An effort has been made in these pages to bring together some of the more valuable of this material.

The author has also presented for the general reader a brief summary of the investigations of the food habits of our common birds, made by the Bureau of Biological Survey, the reports of which were originally published in bulletins to which most readers do not have access.

The author has had especially in mind one large group of readers, who have something of a professional interest in this subject, namely, the teachers of the country, who are now teaching children about birds in nature-study and through bird clubs. The last chapter has been specially prepared for their use, in the hope that it may prove helpful to them in teaching this subject to children.

The author acknowledges his indebtedness to those who have so kindly looked over portions of the manuscript and given suggestions thereon: to the Bureau of Biological Survey for looking over Chapters VII to XI inclusive; to Mr. Ernest Ingersoll for reading Chapters XVI, XVII, and XVIII; to Mr. Edward H. Forbush for reading Chapters I to VI, inclusive, and XII to XV, inclusive; and to Miss Helen M. Reynolds for suggestions on Chapter XXIII. Special thanks are due to Mr. Forbush for his courtesy in sending advance sheets of his annual

PREFACE 1X reports and of his bulletin on the Domestic Cat, from both of which much valuable material was obtained. The entire manuscript has been read by Mr. Francis H. Allen, who has given many valuable suggestions.

G. H. T.

Mankato, Minn.

; Me i vi | te kon .

PART I The Value of Birds

A. Tretr stHetic VALUE AS A SUBJECT FOR STUDY

I. Brrp TRAVELERS .

Discovery of America — ihn tined ane He Sain — Regularity of migration — Distances birds travel — Winter homes — Speed and height — Routes of migration — How birds find their way — Causes of migration.

II. Brrp Music

Why birds sing — Becaenl oe song — Time of ve of song — Music of songs — Methods of recording songs — Similarity to human music — Classification of songs — Variations in songs — Call-notes.

Ill. Brrp Homes .

Time of building — Teese of nests — Materials — Shape — Time occupied in building — Nesting-habits of cowbird — Number of broods — Change in nesting-habits.

Eggs — Incubation — Condition of young when

hatched — Feeding young — Brooding young — A house

wren’s day — Care after leaving nest — Enemies of nestlings.

VY. Cotors AND PLUMAGE oF Brirps .

_ Moulting — Change due to wear — Changes in oalo® — Differences due to sex — Protective coloration.

VI. How to Know rue Birps , Attractions of bird-study — Sdenkherigt of Pia Where to find birds — When to find birds — How to study birds — What to study — Bird-photography — Table of fifty common land-birds.

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IX.

XI.

XII.

XIII.

CONTENTS

B. Tuetr Economic VALUE

FRIENDS AMONG THE Brrps As DESTROYERS OF Insect PEsts r Bureau of Biological ia a — Methods of detect ing food of birds — Harm done by insects — Nature’s check on insects— Service performed by birds —

Amount of food eaten by birds — Value of nestling birds ~

— Control of insect outbreaks — Division of labor — Birds of a Maryland farm — Birds and human health.

FRIENDS AMONG THE BrirpDSs AS DESTROYERS OF WEED SEEDs.

Harm done by eerie — Charicteneties that make weeds troublesome — Birds as destroyers of weed seeds — Amounts of weed seeds eaten — Effect on weed-patches.

Birps AS Destroyers oF Ropent Pests. .

Harm done by rodent pests — Value of hawks and owls — Study of food of hawks and owls — Classification of hawks and owls — Money value of hawks and owls.

. FOES AMONG THE Brrps

Fruit-eaters — Injury to grain — Decknicncn of poultry — Damage to trees and wood products — Destroying beneficial insects — Injury to valuable birds — Preventing depredations of birds.

STRIKING THE BALANCE

Harmful birds — Neutral eye —- Benchaal birds — Table of food of birds.

PART II Enemies of the Birds CHANGES IN THE NumMBERS OF BIRDS Yee

Extinct birds — Species in danger of extermination — Decrease of game-birds and shore-birds— Have song-birds decreased ?

Tue Naturat ENEMIES oF Birps

Four-footed enemies — Feathered enemies — The elements.

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CONTENTS

XIV. Brrp Enemiss Intropucep By Man: THE Cat AND THE ENGLISH SPARROW

The Cat.

Method of doing harm — Opinions of bird-students — Number of birds killed by cats — Cats as disease-carriers — Remedies.

The English Sparrow.

Ways in which it is harmful — Remedies: — Shooting — Poisoning — Trapping.

XV. Man As AN ENEMY OF THE BrIRDs .

Advance of civilization — Shooting for sport — Shooting for market — The milliner’s trade — Egg-collecting — Remedies.

PART III Bird-Protection

A. ProtrectivE AGENCIES

XVI. WorkK or THE AUDUBON SOCIETIES.

History of the Societies — American Ornithologists’ Union — Work of National Association of Audubon Societies:

Legislation — Warden work — Egret-protection

— Publications — Junior Audubon classes —

Field agents.

State Societies.

XVII. Brrp-Protection By GOVERNMENTS — STATE AND NATIONAL .

Work of State Governments: History of legislation — Model law — Bird day — Laws for game-birds — Summary.

Work of National Government:

Bureau of Biological Survey —Lacey Act — Migratory bird law — Tariff regulations — Bird reservations.

XVIII. Brrp Cruss PaO its. ce rele ae

Meriden Bird Club — Brush Hill Bird Club —

Burroughs Nature Club — Liberty Bell Bird Club —

Private game preserves — Summary of results in bird-protection.

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. 209 xiv CONTENTS

B. Artrractine Brrps XIX. Nestinc-Boxrs oe) | a Peery).

Reasons for attracting birds — Birds using boxes — Types of houses — Imitation both inside and outside — Imitation outside only — No attempt at imitation — Entrance opening — Putting out the house — Martin-houses — Open Houses — Nesting-material — Dealers in apparatus to attract birds.

XX. Feepinc tHe WINTER Birps ... .

Reasons for feeding birds — Birds to expect — Kinds of food — Methods of putting out food — Diffculties.

XXII. FounTAINS AND SHRUBS FOR THE BIRDS . Fountains:

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Essentials — Location — Plans for fountains —

Fountains on lawns — Visitors at fountains. Shrubs: Planting for shelter — Planting for nesting-sites — Planting for food.

Calendar for attracting birds.

XXII. Domestication or Wixtp Birps cbahe

Success achieved — Methods of rearing wild birds — Rearing the bob-white — Rearing ducks — Attracting wild ducks.

PART IV Bird-Study in Schools

XXIII. Teacuinc Brro-Protection IN THE SCHOOLS:

Purposes of bird-study — Materials for bird-study — Hand work— Bird games— Bird calendar — Using children’s activities— Field trips — Bird clubs — Bird day — Relation of bird-study to other subjects — Essentials of a good lesson — A type lesson — Outline of bird-study by grades and seasons — Series of lessons.

BiBLIOGRAPHM 6c): y 0) ort

ENDER eo a5!) ee

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ILLUSTRATIONS

A Brrp Garprn . . . ....__. Colored Frontispiece From a drawing by Amy M. Sacker

Buivuesirps, MALE AND FEMALE $0 So ane ht ae So 4 From a drawing by Louis Agassiz Fuertes

Rosin SINGING I Sd ht des hand WE From a drawing by Louis Agassiz Fuertes

LONG-BILLED MarsH Wren at Nest... .. . 2&6

InsIDE oF House WrEN’s Nestinc-Box . . .. . 2

Youne Green Herons In Nest . . .. . . 80

Two-Storiep Nest or YELLOW WARBLER, SHOWING COW-

BIRD'S EGG SEALED IN LOWER STORY . TIMER oN sO A Wren Motuer anp Her Famiry .... . 88 MorTHEerR WORKS WHILE FatuHer sincs. Pair or House WRENS - ° . . e ° e e e * ° . 88

BALTIMORE OrIoLES, MALE AND FemALE . . . . 46 From a drawing by Louis Agassiz Fuertes

TowHEEr, OR CHEWINK, MALE AND FEMALE (colored) . 50 From a drawing by Louis Agassiz Fuertes

RED-HEADED WoopPEcKER (colored) Suite lap AO id Wie cab From a drawing by Louis Agassiz Fuertes

SPECIMEN LEAF FROM A Birp NoteBook . . . . 58

A Useruu Citizen. Housr Wren. ... . .. 66

DraeraM oF Foop or Aputt House Wren... 66

From Yearbook of Department of Agriculture for 1900

Downy Wooprecker (colored) . . . . « « « From a drawing by Louis Agassiz Fuertes

XV1 ILLUSTRATIONS

Fox Sparrows, Eaters oF WrED SEEDS . .. . From a drawing by R. Bruce Horsfall

Gouprincu (colored) Bis a): LN) Sema aaa aontra Nt at hes 5 From a drawing by Louis Agassiz Fuertes

ScrREECH OWL . . . Spl es dy: Wolke From a drawing by R. nee Horsfall

ENGLISH SPARROWS, Mate AND FEMALE . . . From a drawing by Louis Agassiz Fuertes

CAT WITH ROBIN Vike sin: eas From a photograph by William Lovell Finley

A Cat THAT DOES NOT KILL Birps PANS ; From a photograph of a cat owned by Prof. Burt G. Wilder

From a photograph reproduced by permission of es Nowa Association of Audubon Societies

Rep SqurrreL, A Nest-RoBBER . . . . . From a photograph by Dr. R. W. Shufeldt

Brrp Isuanp, Fioripa. RESERVATION OWNED BY THE NATIONAL ASSOCIATION OF AUDUBON SOCIETIES

From a photograph by C. E. Baynard reproduced by permission of the National Association

CALIFORNIA Murres oN THREE ArcH ROCKS OFF THE OREGON COAST, ONE OF THE GOVERNMENT Birp REs- ERVATIONS

From a photograph ie William i Finley sly i. T. poniten

JOHN BuRROUGHS AT THE DEDICATION OF “‘ WREN’s NEs?v”’ In ATLANTA, GA., BY THE BuRROUGHS NaTuRE CLUB From a photograph by Albert H. Pratt

Fietp Day in Renwick Woops, Itnaca, N.Y. Mr. L.

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A. FUERTES ADDRESSING THE CaAyuGA Brrp CtusB. . 214

From a photograph by Arthur A. Allen

ILLUSTRATIONS

LONGITUDINAL SECTIONS OF WoODPECKER’S HOLE AND OF Von Brerurepscu Nestinc-Box From Hiesemann’s “‘ How to Attract and Peetent Wild Birds”

Naturau NEstinc-SITE OF A FLICKER IN AN OLD APPLE TREE

THREE Types oF Nestinc-Boxes wend tie From a photograph by J. R. Snow

Open Nestinc-Boxrs ror Rosin AND PH@BE From a photograph by J. R. Snow

BLUEBIRD AT ENTRANCE TO Nestinc-Box . Hovusrt WrREN AND Tomato-Can HovussE

TREE SwALLow at Nestinc-Box From a photograph by W. H. Phillips

Martin-HovusE ACCOMMODATING Fivr THousanp Birps From a photograph by C. E. Hamilton

ScreEecH-Ow.L In Nestinc-Box From a photograph by E. H. Forbush

Sone Sparrow at Luncu-CountTER

Downy Wooprrecker At Luncu-CountTER . CHICKADEE FEEDING FRoM Hand ..... . Hermit Turuse at Luncu-Counter

A Brrp’s TEPEE, MADE OF BEAN-POLES WITH THE VINES STILL ATTACHED

From a photograph by ie M. Che

MeeeteesUPPLYING Frep-Box . ..-. . From a photograph by Edwin C. Brown

SuET-BASKETS .. Saas Wh ate tis gris From a photograph by J. Te ea

Rep-BREASTED NUTHATCH, PERCHED ON HAND . . From a photograph by Laurence J. Webster

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XVUl ILLUSTRATIONS

Wuitr-BrEASTED NUTHATCH, FEEDING FROM HaAnp . 254 From a photograph by Edwin C. Brown

SHELTER FOR Brirps’ Foop. FIFTEEN BIRDS FEEDING, — Sone Sparrows, TREE SPARROWS, JUNCOS . . . 258

From a photograph by William C. Horton Winpow AND Movine Foop-SHELVES . . . . . 258

Bos-WHITE REARED IN CAPTIVITY .. : . 262 Reproduced by permission of the National Ree of Audubon Societies

CoNncRETE Brrp FouNTAIN ON THE AUTHOR’S LAWN... 262

ScHooLt Brrp CALENDAR ete oo ee From a photograph by A. D. Whedon

FEEDING-STATION FOR BrirDS IN YARD OF TRAINING- ScHoot, MANKATO STaTE NorRMAL SCHOOL, MINNESOTA 284

ScHoout Birp Fountain, Passaic, N.J. 2 Od Me

JUNIOR AUDUBON CLAss AT TRAINING-SCHOOL, MANKATO, MInn. Ae, 2 nT, te At Geo From a Bi neces by a D. Whedon

The illustrations, except as otherwise stated, are from photographs by the author.

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Chapter I Bird Travelers

Discovery of America. The subject of bird migration is of special interest to Americans, because it is probable that migrating birds aided Columbus in the discovery of America. During the latter part of his voyage, when his sailors were beginning to mutiny, he fell in with flocks of birds which were making their annual flight from the Bermudas to the Bahamas. Columbus followed these birds and was thus guided to land. Otherwise it is quite possible that he could not have induced his sailors to continue farther, and thus the discovery of America would have been postponed.

Recent records of migration. During recent years, there has been kept at Washington a very complete record of the facts of migration, relating to the times and routes of migration and to the winter homes of birds. For more than twenty years these records have been collected by the Bureau of Biological Survey, through the codperation of over two thousand bird students throughout North America, so that now they have a large array of reliable data regarding bird migration, comprising over a half-million records.

Changes due to migration. The conspicuous seasonal changes in bird life which occur regularly every year are due to bird migration. Birds may be divided into four groups in accordance with the portion of the year that they remain in a given locality. Permanent residents remain in a locality all the year. In the cold Northern States these include such common birds as the blue jay, nuthatch, chickadee, downy woodpecker, goldfinch, and a few others. Farther south the list becomes longer.

Summer residents remain for the summer only, during which season they are nesting. They spend the winter in regions farther south. Most of the common birds found during the summer in the northeastern section of the United States belong to this group, such as the oriole and the house wren.

Winter residents are found in a locality only during the winter, the summer being spent in regions farther north. In the Northern States, this group includes such birds as the winter wren, snow bunting, tree sparrow, redpoll, and red-breasted nuthatch.

Transient visitants are birds which are seen for a few weeks in the spring and again for a few weeks in the fall as they are migrating. These birds spend the winter farther south and the summer farther north, and are seen only when passing through, on their way to and from their breeding-grounds. Many warblers belong to this group. The birds which belong in each of these four groups vary according to the locality.

The general changes in bird life due to migration which occur annually in any locality may be briefly summarized as follows: During the winter months the birds found in a locality belong to the permanent residents and winter residents. For several months there is little change in the kinds of birds seen. But beginning with the early spring the migration commences, the exact date varying with the latitude and the weather. New birds continue to come in large numbers up to the middle or last of May, some remaining for the summer and others passing ~ farther north. Meanwhile the winter residents have been leaving. Then follows the breeding-season, and for several months there is little change in the kinds of birds seen. About the first of September the fall migration begins, extending into November, the birds gradually leaving for the South, slipping away so quietly that they may be gone for some time before their absence is noted. In the late fall the winter residents arrive, and bird life settles down again to the winter quiet. Thus this annual change occurs year after year with great regularity.

Regularity of migration. The time at which each species of bird arrives at a certain place varies little from year to year for most birds. The date when the early migrants arrive may vary considerably according to the season, but the dates for the later migrants are fairly constant.

The order in which the various birds arrive is also well fixed. Certain birds are always among the first migrants regardless of the season, such as the robin and the bluebird, and other birds are always among the last migrants to arrive, such as the indigo bunting and wood pewee, and this order remains about the same from year to year.

Distances. The distances that birds migrate vary greatly with the species. Some birds may migrate southward only a few miles; others travel farther, to the Southern States; and over a hundred species leave the United States. Some winter in Central America, some in the northern part of South America, and still others in the southern part of South America. Some warblers which nest in Alaska probably travel to Brazil, a distance of seven thousand miles.

Golden plover. The two most noted travelers among birds are the golden plover and the Arctic tern. The golden plover nests along the Arctic coast of North America. It then proceeds to Labrador and Nova Scotia, and from here it may make a continuous flight, in pleasant weather, of twentyfour hundred miles, to the coast of South America. It then passes on to Argentina, where it spends the

BLUEBIRD

Upper, male; lower, female

Brus mame 4s winter. It returns north by a different route, passing along the western part of South America and through the United States by the Mississippi Valley, and thence to the northern coast of North America, its nesting-site, a distance of eight thousand miles from its winter home.

Arctic tern. The Arctic tern has even a longer range of travel than the golden plover. Some of these birds breed along the Arctic coast of North America, a nest having been found within seven and a half degrees of the North Pole. Its winter home is eleven thousand miles away, within the Antarctic Circle, within sixteen degrees of the South Pole. Thus the bird flies almost from pole to pole, twice a year, a journey of twenty-two thousand miles, a distance nearly equal to the earth’s circumference. Mr. W. W. Cooke points out that, as a result of being near the poles for so much of the year, it lives for about eight months in regions of perpetual sunshine, and during the rest of the year its days are much longer than its nights. It might well be called the bird of sunshine.

Winter homes. As one watches the birds in their flight, it is interesting to think of the countries from which they have come, and of the varied scenery which their keen eyes have looked upon. The hummingbird that visits our garden flowers has seen the Panama Canal; the Baltimore oriole that swings its nest from our elm trees has seen the Andes in

Colombia; the rose-breasted grosbeak spends his winter just over the equator in Ecuador; the kingbird has perhaps flown above the waters of Lake Titicaca in Bolivia and Peru; the bobolink has traveled from Paraguay to build his nest in our meadows; the red-eyed vireo has visited the coffee plantations of southwestern Brazil; the barn swallow that builds his mud nest in our barns will return to the Pampas in Argentina for his winter sojourn; while some of the nighthawks that nest in Alaska may travel to the southern part of South America, to Patagonia, a distance of about seven thousand miles and of about one hundred and fifteen degrees of latitude.

Speed. The speed with which birds migrate varies with different species of birds and with the same species of bird in different parts of its journey. In general, birds travel faster during the latter part of their journey than during the first part. During the first part of March, the robin averages thirteen miles a day in migrating from southern Iowa to central Minnesota. From here its speed keeps increasing till it is traveling at the rate of seventy miles a day when it reaches Alaska by the middle of May. The robins along the Atlantic Coast travel more slowly, at the rate of seventeen miles a day.

The average speed for all species of birds is twenty-three miles per day from New Orleans to southern Minnesota. From this locality some species travel northward at the rate of forty miles a day, and still farther north some at seventy-two miles, others at one hundred and sixteen miles, and five species, on arriving in Alaska, are traveling at the rate of one hundred and fifty miles a day.

The figures here given are for the species as a whole, not for individual birds. Usually birds migrate only a few hours during the night and then rest for a day or two, so that the average rate at which a species migrates is much less than for an individual bird. Our common small birds probably travel at the rate of about thirty miles an hour while migrating; ducks and geese may travel at the rate of forty-five miles an hour. Thus during a single night birds may travel from two hundred to four hundred miles.

Daily time of migration. Some birds migrate by day, some by night, and some both by day and night, but most are night travelers. The time selected by a bird for migration depends on its power of flight, its method of procuring food, and its disposition. The warblers, vireos, and thrushes migrate by night, the swallows and hawks by day; while ducks, shore-birds, and sea-birds migrate both by day and night.

Routes. As birds travel between their winter and summer homes, it is found that they follow fairly well-defined routes. In the central United States the Mississippi Valley is the most common route,

‘ and in the eastern United States, the coast-line. The route by which a bird travels north is usually the same as the one by which it returns south, although there are some exceptions to this rule.

When birds which are en route for South America reach the Gulf Coast of the Southern States, several routes are possible. A few birds pass from Florida and follow the chain of islands extending southeast —the Bahamas, Haiti, Porto Rico, and the Lesser Antilles — and thence to South America. A few fly from southern Florida to Cuba, thence to Jamaica, and then make the flight of five hundred miles from Jamaica to South America: the bobolink takes this route. A few birds, like the cliff swallows, follow along the coast of Mexico; but the great majority of species fly directly from the Gulf Coast of the Southern States across the Gulf of Mexico to the southern shore of the Gulf, a distance of from five hundred to seven hundred miles. From there the journey is continued through Central America to South America.

Another route much used by water-birds extends - from Nova Scotia to the Lesser Antilles and the northern coast of South America. It was the birds which were migrating along a portion of this route that guided Columbus to land.

How birds find their way. One of the puzzling problems of migration is how birds find their way during these long journeys. On June 7, 1911, a chimney swift fell through an opening in a chimney into a room of a house located in Meriden, New Hampshire. Mr. E. H. Baynes was in the room and placed on the bird a small numbered leg-band and let the bird go. About one year later, on June 15, 1912, a chimney swift again fell through the same hole into the same room, and when Mr. Baynes took up the bird he found it to be the same one he had banded the year before. This bird had traveled to Central America, spent the winter there, and then traveled back to the same town, and to exactly the same chimney it had occupied the previous year. How had it been able to find its way over this long route back to the same nesting-site?

Bird’s sight. Many theories have been advanced to explain how birds find their way. Probably no one theory will satisfy all conditions. There are doubtless many factors needed to give a satisfactory explanation. One important factor is the bird’s sight. Birds have very keen eyesight, and it seems probable that birds flying at a great height may be guided by conspicuous landmarks, such as mountain-chains, coast-lines, and river-valleys which extend in the same direction as the routes of migration. In North America, the coast-lines and mountain-chains and the Mississippi Valley extend in the general direction in which most of the birds migrate. But this explanation alone is not sufficient, as birds may migrate at right angles to these landmarks, and may find their way in a fog when landmarks are invisible, or over large bodies of water where no landmarks can be seen; and frequently birds fly so close to the ground or water that they cannot see any landmarks. And again birds may travel straight for long distances over routes which they have never seen before.

Sense of direction. Still another suggestion is that birds have a sense of direction which enables them to find their way. This is simply ascribing a power to birds without any real explanation, but experiments which have been made with birds seem to show quite conclusively that some birds do possess this sense of direction. Several birds were captured on Bird Key south of Florida, and were placed in the hold of a steamship and taken north to Cape Hatteras, a distance of about one thousand miles from their nesting-sites, and released. Five days later, two of them were back on their nests. In this case no other explanation seems possible than that the birds found their way through a sense of direction, as the birds had never flown over this route before, and could not see the way over which they had come, and so could not make use of any landmarks.

Causes of migration. The most puzzling of all questions concerning migration is, why do birds migrate? At the outset it may be stated that bird students are not agreed as to the causes of migration, but brief reference may be made to a few of the theories which have been put forward at various times to explain the cause of bird migration.

Food and temperature. It is very commonly stated that lack of food and low temperatures cause birds to migrate. But even a very hasty examination of the facts shows that these do not explain migration. The fall migration begins during the late summer, when the temperature is still high, and at a time when insect life is abundant. Furthermore, during the spring migration, birds are traveling into regions where the temperature is lower and insect life is less abundant than in the regions which they are leaving. And again, some tropical sea-birds migrate from one section to another where the conditions of temperature and food-supply are practically the same.

Glacial theory. One theory relates the origin of bird migration closely with the glacial age. Fossils which have been found show that before this age North America had a warm climate, even in its northern portions. ‘This climate must have been well adapted for bird life during all parts of the year. As the ice-sheet began to extend south, the birds were driven before it, and as it melted and receded north, the birds followed it back. In accordance with this theory, the habit which the birds thus acquired of moving back and forth, following the oscillations of the ice-sheet, was inherited eventually by the birds as an instinct and still exists to this day.

Physiological explanation. None of these theories is generally accepted by bird students as giving a satisfactory explanation of migration. It is probable that birds have a physiological instinct which prompts them to migrate in order to rear their young, just as their instinct leads to other actions, such as singing, mating, nest-building, egg-laying, and incubating. But this statement, of course, gives no explanation as to how and why this instinct originated.

Chapter II

Why birds sing. Of the many interesting sounds in nature, bird songs are the most charming. The song of birds is a sexual characteristic developed in the male during the nesting-season. It is closely related in the first place with mating, and is one means by which the male attracts the attention of the female during courtship; it continues, however, during most of the nesting-season. Occasionally the female has been known to sing, as with the rose-breasted grosbeak and cardinal. While singing is primarily a sexual instinct with the birds, yet it may probably be carried on for the esthetic pleasure derived, as some birds seem to show appreciation of the harmony of music.