The Bird Study Book

by T. Gilbert Pearson

Screech Owl and Its Prey

The Terror That Flies by Night.—Among the chief enemies of rodents in North America are the nineteen species of Owls, untold numbers of which are abroad every night searching through fields and forests for just such creatures as these. The digestive processes of Owls are such that the hard, indigestible portions of their food are disgorged in the form of balls and may often be found beneath their roosting places. One of our most odd-looking birds is the Barn Owl. Being nocturnal in its habits it is rarely seen unless one takes the trouble to climb into unfrequented church towers, the attics of abandoned buildings, or similar places which they seek out for roosting purposes. Some years ago the naturalist, Dr. A. K. Fisher, discovered that a pair of Barn Owls had taken up their abode in one of the towers of the Smithsonion Institution building. He found the floor thickly strewn with pellets composed of bones and fur which these birds and their young had disgorged. He collected two hundred of these and took them to his laboratory. A painstaking examination showed that they contained four hundred and fifty-three skulls. Here is his list made out at the time: two hundred and twenty-five meadow mice, two pine mice, twenty shrews, one star-nosed mole, and one Vesper Sparrow. It is plain to be seen that great good was accomplished in the community by this pair of Owls and their young, for the evil effects of the rodents in life must have far overbalanced the good service of the one useful Vesper Sparrow.

A Seldom Recognised Blessing.—There are some large predatory birds which destroy the lives of many game birds and others of the weaker species. On game farms, therefore, an unpleasant but necessary task is the shooting or trapping of Hawks and Owls. At first thought it might seem best to wage a war of absolute extermination on these offenders, and some game-keepers urge that this should be done. Personally I am opposed to any such course of action, one reason being that this would not necessarily forward the best interests of the game birds it is desired to serve. So important and yet so unexpected is the ultimate effect of the activities of predatory creatures that in a state of nature I am convinced the supply of game birds is increased rather than decreased by being preyed upon. Like all other creatures, birds are subject to sickness and disease, but by the laws of nature it appears that they are not designed to suffer long. Their quick removal is advisable if they are to be prevented from spreading contagion among their fellows, or breeding and passing on their weakness to their offspring. Sometimes the Hawk, dashing at a covey of game birds, may capture one of its strongest and healthiest members, but the chances are that the afflicted member, which is not so quick on the rise or is a little slower on the wing, is the one to be taken. Just as some savages are said to put to death the incompetent and unfit, so do the laws operate which govern wild life. If, therefore, we should destroy all the Hawks, Owls, wild cats, foxes, skunks, snakes, and other predatory creatures, it is an open question whether in the long run our game birds would be the gainers thereby.

Some time ago I visited a large game farm in one of the Southern States, where for several years the owner had been engaged in raising English Ring-necked Pheasants. The gamekeeper stated that there were about six thousand of these brilliantly coloured birds on the preserve at that time. He also pointed with pride to an exhibit on the walls of a small house. An examination showed that the two sides and one end of this building were thickly decorated with the feet of Hawks, Crows, Owls, domestic cats, minks, weasels, and other creatures that were supposed to be the enemies of Pheasants. Two men were employed on the place to shoot and trap at all seasons, and the evidences of their industry were nailed up, to let all men see that the owner of the big game farm meant to allow no wild bird or animal to fatten on his game birds.

A year later I again visited the same preserve and found great lamentation. More than five thousand Pheasants had been swept away by disease within a few weeks. Is it going too far to say that the gunmen and trappers had overdone their work? So few Hawks or Owls or foxes had been left to capture the birds first afflicted, that these had been permitted to associate with their kind and to pass on weakness and disease to their offspring until the general health tone of the whole Pheasant community had become lowered. In the end five-sixths of the birds had succumbed to the devastations of disease.

All birds have their part to play in the great economy of the earth, and it is a dangerous experiment to upset the balance of Nature.

CHAPTER VII

CIVILIZATION'S EFFECT ON THE BIRD SUPPLY

Twelve hundred kinds of wild birds have been positively identified in North America. About one-third of this number are called sub-species, or climatic varieties. To illustrate the meaning of "sub-species," it may be stated that in Texas the plumage of the Bob-White is lighter in colour than the plumage of the typical eastern Bob-White, which was first described to science; therefore, the Texas bird is known as a sub-species of the type. Distributed through North America are nineteen sub-species of the eastern Song Sparrow. These vary from the typical bird by differences in size and shades of marking. In a similar way there are nine climatic variations of Screech Owls, six Long-billed Marsh Wrens, and fourteen Horned Larks. It is difficult to explain why this variation in colour and size is so pronounced in some species and yet is totally absent in others of equally wide range. The Mourning Dove breeds in many localities from the southern tier of Canadian Provinces southward throughout the United States and Mexico, and yet everywhere over this vast range the birds are the same in size and colour. Nowhere do the individuals exhibit any markings suggestive of climatic influences.

Some birds are very rare and are admitted to the list of North American species because of the fact that during the years a few stragglers from other parts of the world have been found on our continent. Thus the Scarlet Ibis from South America, and the Kestrel and Rook from western Europe, are known to come to our shores only as rare wanderers who had lost their way, or were blown hither by storms. Eighty-five species of the birds now listed for North America are of this extra-limital class. Among those naturally inhabiting the country, some are, of course, much more abundant than others, thus every one knows that Bald Eagles are comparatively rare, and that Robins and Chipping Sparrows exist by millions.

The Number of Birds in Different States.—The number of kinds of birds found in any one State depends on the size of the State, its geographical situation, and the varieties of its climate as affected by the topography in reference to mountains, coastlines, etc. The number of bird students and the character of their field studies determine the extent to which the birds of a State have been catalogued and listed. The following list indicates the number of kinds of birds that have been recorded in forty-three of the States and the District of Columbia. The authority for the statement in each instance and the year in which the figures were given is also stated:

Alabama, 275 (Oberholser, 1909).
Arizona, 371 (Cooke, 1914).
Arkansas, 255 (Howell, 1911).
California, 541 (Grinnell, 1916).
Colorado, 403 (Cooke, 1912).
{123}
Connecticut, 334 (Sage and Bishop, 1913).
Delaware, 229 (Rennock, 1908).
District of Columbia, 293 (Cooke, 1913).
Florida, 362 (Thurston, 1916).
Idaho, 210 (Merrill, 1898).
Illinois, 390 (Cory, 1909).
Indiana, 321 (Butler, 1898).
Iowa, 356 (Anderson, 1907).
Kansas, 379 (Bunker, 1913).
Kentucky, 228 (Garman, 1894).
Louisiana, 323 (Byer, Allison, Kopman, 1915).
Maine, 327 (Knight, 1908).
Maryland, 290 (Kirkwood, 1895).
Massachusetts, 369 (Howe and Allen, 1901).
Michigan, 326 (Barrows, 1912).
Minnesota, 304 (Hatch, 1892).
Missouri, 383 (Widmann, 1907).
Nebraska, 418 (Swenk, 1915).
Nevada, 250 (Hoffman, 1881).
New Hampshire, 283 (Allen, 1904).
New Jersey, 358 (Stone, 1916).

New Mexico, 314 (Ford, 1911).
New York, 412 (Eaton, 1914).
North Carolina, 342 (Pearson and Brimley, '16).
North Dakota, 338 (Schmidt, 1904).
Ohio, 330 (Jones, 1916).
Oregon, 328 (Woodcock, 1902).
Pennsylvania, 300 (Warren, 1890).
Rhode Island, 293 (Howe and Sturtevant, 1899).
South Carolina, 337 (Wayne, 1910).
Tennessee, 223 (Rhoads, 1896).
Texas, 546 (Strecker, 1912).
Utah, 214 (Henshaw, 1874).
Vermont, 255 (Howe, 1902).
Virginia, 302 (Rives, 1890).
Wellington, 372 (Dawson, 1909).
West Virginia, 246 (Brooks, 1913).
Wisconsin, 357 (Kumlien and Hollister, 1903).
Wyoming, 288 (Knight, 1902).

For the five remaining States no list of the birds has as yet been issued.

Increase of Garden and Farm Birds.—The effect of civilization on the bird life of North America has been both pronounced and varied in character. Ask almost any one over fifty years of age if there are as many birds about the country as there were when he was a boy, and invariably he will answer "No!" This reply will be made, not because all birds have decreased in numbers, but because there has come a change in the man's ideas and viewpoint; in short, the change is chiefly a psychological one. The gentleman doubtless does not see the birds as much as he did when he was a boy on a farm, or if he does, they do not make the same impression on his mind. It is but another example of the human tendency to regard all things as better in the "good old times." Let us turn then from such well-meant but inaccurate testimony, and face the facts as they exist. I have no hesitation in saying that with many species of Finches, Warblers, Thrushes, and Wrens, their numbers in North America have greatly increased since the first coming of the white men to our shores.

It is a fact well known to careful observers that the deep, unbroken forests do not hold the abundance of bird life that is to be found in a country of farmlands, interspersed with thickets and groves. Originally extensive regions of eastern North America were covered with forests wherein birds that thrive in open countries could not find suitable habitation. As soon as the trees were cut the face of the country began to assume an aspect which greatly favoured such species as the Bobolink, Meadowlark, Quail, Vesper Sparrow, and others of the field-loving varieties. The open country brought them suitable places to nest, and agriculture increased their food supply. The settlers began killing off the wolves, wild cats, skunks, opossums, snakes, and many of the predatory Hawks, thus reducing the numbers of natural enemies with which this class of birds has to contend.

When the swamp is drained it means that the otter, the mink, and the Wild Duck must go, but the meadowland that takes the place of the swamp provides for an increased number of other species of wild life.