Bird-life; a guide to the study of our common birds/Chapters/The bird, its place in Nature and relation to man
BIRD-LIFE.
CHAPTER I.
THE BIRD : ITS PLACE IN NATURE AND RELATION TO MAN.
The Bird's Place in Nature.[1]—About thirteen
thousand species of birds are known to science. The
structure of many of these has been carefully studied,
and all have been classified, at least provisionally.
Taken as a whole, the class Aves, in which all birds are
placed, is more clearly defined than any other group of
the higher animals. That is, the most unlike birds are
more closely allied than are the extremes among mammals,
fishes, or reptiles, and all living birds possess the
distinctive characters of their class.
When compared with other animals, birds are found to occupy second place in the scale of life. They stand between mammals and reptiles, and are more closely related to the latter than to the former. In fact, certain extinct birds so clearly connect living birds with rep- tiles, that these two classes are sometimes placed in one group—the Sauropsida. The characters that distinguish birds from mammals on the one hand, and from reptiles on the other, are more apparent than real. Thus flight, the most striking of a bird's gifts, is shared by bats among mammals. Egg-laying is the habit of most reptiles and of three mammals (the Australian duckbill and the echidnas). But incubation by one or both of the parents is peculiar to birds, though the python is said to coil on its eggs.
Birds breathe more rapidly than either mammals or reptiles, and their pneumatieity, or power of inflating numerous air-sacs and even certain bones, is unique.
The temperature of birds ranges from 100° to 112°, while in mammals it reaches 98° to 100°, and in the comparatively cold-blooded reptiles it averages only 40°.
The skull in mammals articulates with the last vertebra (atlas) by two condyles or balls ; in birds and reptiles by only one. In mammals and birds the heart has four chambers ; in reptiles it has but three.
Mammals and reptiles both have teeth, a character possessed by no existing bird; but fossil birds apparently prove that early in the development of the class all birds had teeth.
Thus we might continue the comparison, finding that birds have no universal peculiarities of structure which are not present in some degree in either mammals or reptiles, until we come to their external covering. The reptile is scaled, and so is the fish ; the mammal is haired, and so are some insects ; but birds alone possess feathers. They are worn by every bird—a fit clothing for a body which is a marvelous combination of beauty, lightness, and strength.
There is good evidence for the belief that birds have descended from reptilian ancestors. This evidence consists of the remains of fossil birds, some of which show marked reptilian characters and, as just said, are toothed.
It is unnecessary to discuss here the relationships of the birdlike reptiles, but, as the most convincing argument in support of the theory of the reptilian descent of birds, I present a restoration of the Archæopteryx, the earliest known progenitor of the class Aves. This restoration is
Fig. 1.—Restoration of the Archæopteryx, a toothed, reptilelike bird of the Jurassic period. (About 1⁄5 natural size.)
based on an examination of previous restorations in connection with a study of the excellent plates which have been published of the fossils themselves.[2] Two specimens have been discovered; one being now in the British Museum, the other in the Berlin Museum. They were both found in the lithographic slates of Solenhofen, in Bavaria, a formation of the Jurassic period, and, together, furnish the more important details of the structure of this reptilelike bird.
This restoration, therefore, while doubtless inaccurate in minor points, is still near enough to the truth to give a correct idea of this extraordinary bird's appearance.
The Archæopteryx was about the size of a Crow. Its long, feathered tail is supposed to have acted as an aeroplane, assisting in the support of the bird while it was in the air, but its power of flight was doubtless limited. It was arboreal and probably never descended to the earth, but climbed about the branches of trees, using its large, hooked fingers in passing from limb to limb.
The wanderings of this almost quadrupedal creature must necessarily have been limited, but its winged descendants of to-day are more generally distributed than are any other animals.[3] They roam the earth from pole to pole ; they are equally at home on a wave-washed coral reef or in an arid desert, amid arctic snows or in the shades of a tropical forest. This is due not alone to their powers of flight but to their adaptability to varying conditions of life. Although, as I have said, birds are more closely related among themselves than are the members of either of the other higher groups of animals, and all birds agree in possessing the more important distinguishmg characters of their class, yet they show a wide range of variation in structure.
This, in most instances, is closely related to habits, which in birds are doubtless more varied than in any of the other higher animals. Some birds, like Penguins, are so aquatic that they are practically helpless on land. Their wings are too small to support them in the air, but they fly under water with great rapidity, and might be termed feathered porpoises. Others, like the Ostrich, are terrestrial, and can neither fly nor swim. Others still, like the Frigate Birds, are aërial. Their small feet are of use only in perching, and their home is in the air.
If now we should compare specimens of Penguins, Ostriches, and Frigate-birds with each other, and with such widely different forms as Hummingbirds, Wood-peckers, Parrots, and others, we would realise still more clearly the remarkable amount of variation shown by birds. This great difference in form is accompanied by a corresponding variation in habit, making possible, as before remarked, the wide distribution of birds, which, together with their size and abundance, renders them of incalculable importance to man. Their economic value, however, may be more properly spoken of under
The Relation of Birds to Man.—The relation of birds to man is threefold—the scientific, the economic, and the æsthetic. No animals more profitable subjects for the scientist than birds. The embryologist, the morphologist, and the systematist, the philosophic naturalist and the psychologist, all may find in them exhaustless material for study. It is not my purpose, however, to speak here of the science of ornithology. Let us learn something of the bird in its haunts before taking it to the laboratory. The living bird can not fail to attract us ; the dead bird—voiceless, motionless—we will leave for future dissection.
The economic value of birds to man lies in the service they render in preventing the undue increase of insects, in devouring small rodents, in destroying the seeds of harmful plants, and in acting as scavengers.
Leading entomologists estimate that insects cause an annual loss of at least two hundred million dollars to the agricultural interests of the United States. The statement seems incredible, but is based upon reliable statistics. This, of course, does not include the damage done to ornamental shrubbery, shade and forest trees. But if insects are the natural enemies of vegetation, birds are the natural enemies of insects. Consider for a moment what the birds are doing for us any summer day, when insects are so abundant that the hum of their united voices becomes an almost inherent part of the atmosphere.
In the air Swallows and Swifts are coursing rapidly to and fro, ever in pursuit of the insects which constitute their sole food. When they retire, the Nighthawks and Whip-poor-wills will take up the chase, catching moths and other nocturnal insects which would escape day-flying birds. The Flycatchers lie in wait, darting from ambush at passing prey, and with a suggestive click of the bill returning to their post. The Warblers, light, active creatures, flutter about the terminal foliage, and with almost the skill of a Hummingbird pick insects from leaf or blossom. The Vireos patiently explore the under sides of leaves and odd nooks and corners to see that no skulker escapes. The Woodpeckers, Nuthatches, and Creepers attend to the tree trunks and limbs, examining carefully each inch of bark for insects' eggs and larvae, or excavating for the ants and borers they hear at work within. On the ground the hunt is continued by the Thrushes, Sparrows, and other birds, who feed upon the innumerable forms of terrestrial insects. Few places in which insects exist are neglected ; even some species which pass their earlier stages or entire lives in the water are preyed upon by aquatic birds.
Birds digest their food so rapidly, that it is difficult to estimate from the contents of a bird's stomach at a given time how much it eats during the day. The stomach of a Yellow-billed Cuckoo, shot at six o'clock in the morning, contained the partially digested remains of forty-three tent caterpillars, but how many it would have eaten before night no one can say.
Mr. E. H. Forbush, Ornithologist of the Board of Agriculture of Massachusetts, states that the stomachs of four Chickadees contained one thousand and twenty-eight eggs of the cankerworm. The stomachs of four other birds of the same species contained about six hundred eggs and one hundred and five female moths of the cankerworm. The average number of eggs found in twenty of these moths was one hundred and eighty-five ; and as it is estimated that a Chickadee may eat thirty female cankerworm moths per day during the twenty-five days which these moths crawl up trees, it follows that in this period each Chickadee would destroy one hundred and thirty-eight thousand seven hundred and fifty eggs of this noxious insect.
Professor Forbes, Director of the Illinois State Laboratory of Natural History, found one hundred and seventy-five larvae of Bibio—a fiy which in the larval stage feeds on the roots of grass—in the stomach of a single Robin, and the intestine contained probably as many more.
Many additional cases could be cited, showing the intimate relation of birds to insect-life, and emphasizing the necessity of protecting and encouraging these little-appreciated allies of the agriculturist.
The service rendered man by birds in killing the small rodents so destructive to crops is performed by Hawks and Owls—birds the uninformed farmer considers his enemies. The truth is that, with two exceptions, the Sharp-shinned and Cooper's Hawk, all our commoner Hawks and Owls are beneficial. In his exhaustive study of the foods of these birds Dr. A. K. Fisher, Assistant Ornithologist of the United States Department of Agriculture, has found that ninety per cent of the food of the Red-shouldered Hawk, commonly called “ Chicken Hawk ” or “ Hen Hawk,” consists of injurious mammals and insects, while two hundred castings of the Barn Owl contained the skulls of four hundred and fifty-four small mammals, no less than two hundred and twenty-five of these being skulls of the destructive field or meadow mouse.
Still, these birds are not only not protected, but in some States a price is actually set upon their heads ! Dr. C. Hart Merriam, Ornithologist and Mammalogist of the United States Department of Agriculture, has estimated that in offering a bounty on Hawks and Owls, which resulted in the killing of over one hundred thousand of these birds, the State of Pennsylvania sustained a loss of nearly four million dollars in one year and a half !
As destroyers of the seeds of harmful plants, the good done by birds can not be overestimated. From late fall to early spring, seeds form the only food of many birds, and every keeper of cage-birds can realize how many a bird may eat in a day. Thus, while the Chickadees, Nuthatches, Woodpeckers, and some other winter birds are ridding the trees of myriads of insects' eggs and larvae, the granivorous birds are reaping a crop of seeds which, if left to germinate, would cause a heavy loss to our agricultural interests.
As scavengers we understand that certain birds are of value to us, and therefore we protect them. Thus the Vultures or Buzzards of the South are protected both by law and public sentiment, and as a result they are not only exceedingly abundant, but remarkably tame. But we do not realize that Gulls and some other water birds are also beneficial as scavengers in eating refuse which, if left floating on the water, would often be cast ashore to decay. Dr. George F. Gaumer, of Yucatan, tells me that the killing of immense numbers of Herons and other littoral birds in Yucatan has been followed by an increase in human mortality among the inhabitants of the coast, which he is assured is a direct result of the destruction of birds that formerly assisted in keeping the beaches and bayous free from decaying animal matter.
Lack of space forbids an adequate treatment of this subject, but reference to the works and papers mentioned below[4] will support the statement that, if we were deprived of the services of birds, the earth would soon become uninhabitable.
Nevertheless, the feathered protectors of our farms and gardens, plains and forests, require so little encouragement from us—indeed, ask only tolerance—that we accept their services much as we do the air we breathe. We may be in debt to them past reckoning, and still be unaware of their existence.
But to appreciate the beauty of form and plumage of birds, tlieir grace of motion and musical powers, we must know them. Then, too, we will be attracted by their high mental development, or what I have elsewhere spoken of as “ their human attributes. Man exhibits hardly a trait which he will not find reflected in the life of a bird. Love, hate ; courage, fear ; anger, pleasure ; vanity, modesty ; virtue, vice ; constancy, fickleness ; generosity, selfishness ; wit, curiosity, memory, reason—we may find them all exhibited in the lives of birds. Birds have thus become symbolic of certain human characteristics, and the more common species are so interwoven in our art and literature that by name at least they are known to all of us.”
The sight of a bird or the sound of its voice is at all times an event of such significance to me, a source of such unfailing pleasure, that when I go afield with those to whom birds are strangers, I am deeply impressed by the comparative barrenness of their world, for they live in ignorance of the great store of enjoyment which might be theirs for the asking.
I count each day memorable that brought me a new friend among the birds. It was an event to be recorded in detail. A creature which, up to that moment, existed
for me only as a name, now became an inhabitant of my woods, a part of my life. With what a new interest I got down my books again, eagerly reading every item concerning this new friend ; its travels, habits, and notes ; comparing the observations of others with what were now my own !
The study of birds is not restricted to any special season. Some species are always with us. Long after the leaves have fallen and the fields are bare and brown, when insect voices are hushed, and even some mammals are sleeping their winter sleep, the cheery Juncos flit about our doorstep, the White-throats twitter cozily from the evergreens. Tree Sparrows chatter gayly over their breakfast of seeds, and Crows are calling from the woods. Birds are the only living creatures to be seen ; what a sense of companionship their presence gives ; how desolate the earth would seem without them !
The ease with which we may become familiar with these feathered neighbors of ours robs ignorance of all excuses. Once aware of their existence, and we shall see a bird in every bush and find the heavens their pathway. One moment we may admire their beauty of plumage, the next marvel at the ease and grace with which they dash by us or circle high overhead.
But birds will appeal to us most strongly through their songs. When your ears are attuned to the music of birds, your world will be transformed. Birds' songs are the most eloquent of Nature's voices : the gay carol of the Grosbeak in the morning, the dreamy, midday call of the Pewee, the vesper hymn of the Thrush, the clanging of Geese in the springtime, the farewell of the Blue-bird in the fall—how clearly each one expresses the sentiment of the hour or season !
Having learned a bird's language, you experience an increased feeling of comradeship with it. You may even share its emotions as you learn the significance of its notes. No one can listen to the song of the Mockingbird withiout being in some way affected ; but in how many hearts does the tink of the night-flying Bobolink find a response ? I never hear it without wishing the brave little traveler Godspeed on his long journey.
As time passes you will find that the songs of birds bring a constantly increasing pleasure. This is the result of association. The places and people that make our world are ever changing ; the present slips from us with growing rapidity, but the birds are ever with us.
The Robin singing so cheerily outside my window sings not for himself alone, but for hundreds of Robins I have known at other times and places. His song recalls a March evening, warm with the promise of spring ; May mornings, when all the world seemed to ring with the voices of birds ; June days, when cherries were ripening ; the winter sunlit forests of Florida, and even the snow-capped summit of glorious Popocatepetl. And so it is with other birds. We may, it is true, have known them for years, but they have not changed, and their familiar notes and appearance encourage the pleasant self-delusion that we too are the same.
The slender saplings of earlier years now give wide-spreading shade, the scrubby pasture lot has become a dense woodland. Boyhood's friends are boys no longer, and, worst of all, there has appeared another generation of boys whose presence is discouraging proof that for us youth has past. Then some May morning we hear the Wood Thrush sing. Has he, too, changed ? Not one note, and as his silvery voice rings through the woods we are young again. No fountain of youth could be more potent. A hundred incidents of the long ago become as real as those of yesterday. And here we have the secret of youth in age which every venerable naturalist I have ever met has convincingly illustrated. I could name nearly a dozen, living and dead, whom it has been my valued privilege to know. All had passed the allotted threescore and ten, and some were over fourscore. The friends and associates of their earlier days had passed away, and one might imagine that they had no interest in life and were simply waiting for the end.
But these veterans were old in years only. Their hearts were young. The earth was fair ; plants still bloomed, and birds sang for them. There was no idle waiting here ; the days were all too short. With what boyish ardor they told of some recent discovery ; what inspiration there was in their enthusiasm !
So I say to you, if you would reap the purest pleasures of youth, manhood, and old age, go to the birds and through them be brought within the ennobling influences of Nature.
- ↑ On the structure of birds read Coues's Key to North American Birds, Part II (Estes & Lauriat); Headley, The Structure and Life of Birds ; Newton's Dictionary of Birds—articles, Anatomy of Birds and Fossil Birds ; Martin and Moale's Handbook of Vertebrate Dissection, Part II, How to Dissect a Bird ; Shufeldt's Myology of the Raven (Macmiilan Co.).
- ↑ For recent papers on the Archæopteryx see Natural Science (Macmillan Co.), vols, v-viii.
- ↑ On the distribution of animals read Allen, The Geographical Distribution of North American Mammals, Bulletin of the American Museum of Natural History, New York city, iv, 1892, pp. 199-244; four maps. Allen, The Geographical Origin and Distribution of North American Birds considered in Relation to Faunal Areas of North America, The Auk (New York city), x. 1893, pp. 97-150; two maps. Merriam, The Geographic Distribution of Life in North America, with Special Reference to Mammalia, Proceedings of the Biological Society of Washington, vii, 1892, pp. 1-64; one map. Merriam, Laws of Temperature Control of the Geographic Distribution of Terrestrial Animals and Plants, National Geographic Magazine (Washington), vi, 1894, pp. 229-238; three maps.
- ↑ Notes on the Nature of the Food of the Birds of Nebraska, by S. Aughey; First Annual Report of the United States Entomological Commission for the Year 1877, Appendix ii, pp. 13-62. The Food of Birds, by S. A. Forbes ; Bulletin No. 3, Illinois State Laboratory of Natural History, 1880, pp. 80-148. The Regulative Action of Birds upon Insect Oscillations, by S. A. Forbes, ibid., Bulletin No. 6, 1883, pp. 3-32. Economic Relations of Wisconsin Birds, by F. H. King ; Wisconsin Geological Survey, vol. i, 1882, pp. 441-610. Report on the Birds of Pennsylvania, with Special Reference to the Food Habits, based on over Four Thousand Stomach Examinations, by B. H. Warren ; Harrisburg, E. K. Meyers, State Printer, large 8vo, pp. 434, plates 100. The English Sparrow in North America, especially in its Relation to Agriculture, prepared under the Direction of C. Hart Merriam, by Walter B. Barrows ; Bulletin No. 1, Division of Economic Ornithology and Mammalogy of the United States Department of Agricul- ture, 1889. The Hawks and Owls of the United States in their Relation to Agriculture, prepared under the Direction of C. Hart Merriam, by A. K. Fisher; Bulletin No. 3. ibid., 1893. The Common Crow of the United States, by Walter B. Barrows and E. A. Schwarz; Bulletin No. 6, ibid., 1895. Preliminary Report on the Food of Woodpeckers, by F. E. L. Beal ; Bulletin No. 7, ibid., 1895. (See also other papers on the food of birds in the Annual Report and Year-book of the United States Department of Agriculture.) Birds as Protectors of Orchards, by E. H. Forbush ; Bulletin No. 3, Massachusetts State Board of Agriculture, 1895, pp. 20-33. The Crow in Massachusetts, by E. H. Forbush; Bulletin No. 4, ibid., 1896. How Birds affect the Farm and Garden, by Florence A. Merriam ; reprinted from " Forest and Stream," 1896, 16mo, pp. 31. Price, 5 cents.