File:Bulletin (Pennsylvania Game Commision), no. 9 (1911) (20507126781).jpg

Title: Bulletin (Pennsylvania Game Commision), no. 9
Identifier: bulletinpennsylv09penn (find matches)
Year: 1911 (1910s)
Authors: Pennsylvania Game Commission
Subjects: Game protection; Birds
Publisher: Harrisburg, Pa. : Pennsylvania Game commission
Contributing Library: Penn State University
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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14 rearing of the young: birds occurs usually during early summer, at the time of the greatest abundance of insects. Young birds require, like the caterpillars, a tremendous amount of food, and sometimes eat considerably over their own weight each day. The food of young birds is, as a rule, insects. Therefore the increase of birds, by the production of their young in the spring, parallels the increase of in- sects, and definitely prevents the development of an insect scourge. During winter millions of eggs and dormant forms of insects are eaten by birds. This winter-consumption is an important part of the insect-regulating program of bird-life. Without the least desire to under-rate the value of birds as in- sect regulators it is only fair to call attention, however, to other factors of control of which bird students in particular, are too often unaware. It is correct for us to value birds as indispensable to human existence, but for us to form the notion that the life of our field and forests, and indirectly that of man, depends entirely upon birds, is failing to acknowledge the importance of one of the great- est insect-regulating factors there are—namely the insects them- selves. It is so easy for us to value these birds which we like, and so easy to class as undesirable all insects (whether we know them or not) because we do not like them, that we take no account of the insects whose existence depends wholly upon and whose ceaseless efforts are expended in devouring other insects—predatory beetles which attack the ground-inhabiting species; dragon flies and their relatives which patrol the air; wasps, some of them microscopic in size, whose perpetuation of species depends upon the parasitism of caterpillars, and a host of other forms. Spiders are not especially enjoyed by us; and yet a little thought will bring to mind their countless webs which have been woven for a principal purpose—the capture of insects. The average ornithologist can easily forget in his zeal for defense of birds, that bats are wholly insectivorous, as are many other mammals—even some which are occasionally rated as carnivorous "vermin". Fish also eat insects. Any friend of the common garden toad will ceaselessly praise him for his insect-kill- ing propensities, and there are numerous reptiles which live on prac- tically nothing but insects. When we consider, therefore, first that all insects are not, as so many suppose, undesirable, and second that there are many other forces which are regulating insect life aside from birds, we can see that statements which lead us to regard birds as our only saviours from starvation, are wrong. And yet not for an instant uo we lesss ni^niv iCf;rt»n kj^t o^^^j. .»-- a. . .^—^ simply understand the situation better, and are more magnanimous in our decisions. Nevertheless a more detailed account of the part birds play in regulating insects may well be considered here. Birds, like most 4 " ^ ^ r I 15 animal forms, are adapted to particular habitats. Some are equipped with long muscular wings, bodies built on speed lines for the least air resistance possible, and small feet,—all adaptations for an aerial existence; others have stiff tails which are to be used as props, strong feet for clinging, and chisel-like bills and barbed tongues, for an existence on tree trunks; others have large and strong feet for terrestrial life; others have very long necks and legs, for searching food in the water; and the feet of others are webbed for swimming. Whatever this adaptation to environment may be, it is concerned chiefly with the matter of procuring food, since upon food depends existence. Insects too are adapted to these different environments. Thus we find various types of birds preying upon, almost exclusively too, the kinds of insects that are found in their environment. Swallows. Swifts, and Nighthawks prey almost altogether on insects which they find in the air. Woodpeckers, Creepers, and Nuthatches, which are adapted to a tree-trunk existence are ceaseless in their search for eggs of various insects which are hidden in the crevices, and for
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Photograph by Robert J. Sim, Riverton, N. J. Fig. 9. NIGHTHAWK OR BULL-BAT BROODING YOUNG A beneficial bird which captures insects on the wing. larvae and other forms of various woodboreia, for which they some- times have to work considerably. Fly-catchers capture insects prin- cipally on the wing, but they capture the species which inhabit woodlands which the Swallows and Swifts would likely never see. Warblers, Vireos, Tanagers and other arboreal birds search th€

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