great is their value from a practical standpoint as to lead tO the belief that 

 were it not for birds successful agriculture would be impossible. 



The stud)' of the economic side of bird Hfe and of the relations of birds to 

 the farmer and horticulturist have been greatly stimulated in the United States 

 by Federal aid and supervision, and in no other country in the world have the 

 activities of birds been so carefully investigated with reference to their practical 

 bearing. Under the Biological Survey of the Department of Agriculture, for 

 instance, is a corps of trained men, who study the food of birds by careful exam- 

 ination of the stomachs of specimens killed for scientific purposes. The information 

 thus gained is supplemented by observations in the field, and the result is a 

 large amount of invaluable data illustrative of the economic relations of many 

 kinds of birds. This storehouse of information has been largely drawn upon in 

 the following pages. 



OUR COUNTRY IS P.\RTICUL.\RLY FORTUNATE IN THE NUMBER AND 

 VARIETY OF ITS BIRDS 



It would be strange indeed if our land, with its vast extent of territory, its 

 diversified landscape, its extensive forests, its numerous lakes and streams, with 

 its mountains, prairies, and plains, had not been provided by Nature with an 

 abundant and diversified bird life. As a matter of fact, America has been favored 

 with a great variety of birds famed both for beauty and for song. America also 

 possesses certain families, as the humming birds and wood-warblers, the like 

 of which exist nowhere else in the world. 



In considering the many kinds of birds in the United States from the 

 practical side, they may not inaptly be compared to a police force, the chief 

 duty of which is to restrain within bounds the hordes of insects that if unchecked 

 would devour every green thing. To accomplish this task successfully, the 

 members of the force must be variously equipped, as we find they are. Indeed, 

 while the 1,200 kinds of birds that inhabit the United States can be grouped in 

 families which resemble each other in a general way, yet among the members 

 of the several families are marked variations of form and plumage and still 

 greater variation of habits, which fit them for their diversified duties. 



As the bulk of insects spend more or less time on the ground, so we find that 

 more birds are fitted for terrestrial service than for any other. Our largest 

 bird family, the sparrows, is chiefly terrestrial, and although its members depend 

 much upon seeds for subsistence they spend no little share of their time search- 

 ing for insects. They are ably aided in the good work by the thrushes, wrens, 

 certain of the warblers, and many other birds. 



Another group is of arboreal habits, and plays an important part in the 

 conserv^ation of our forests, the true value of which we have only recently 

 learned to appreciate. So many insects burrow into trees that a highly specialized 

 class of birds — the woodpeckers — has been developed to dig them out. The 

 bills, tongues, feet, and even the tails of these birds have been cunningly adapted 

 to this one end, and the manner in which this has been done shows how fertile 

 Nature is in equipping her servants to do her bidding. 



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