. Bulletin of the Department of Agriculture. Agriculture; Agriculture. Washington, D. C. T July 20,1923 REPORT ON BIRD CENSUSES IN THE UNITED STATES, 1916 TO 1920. By May Thacher Cooke, Assistant in Biological Investigations, Bureau of Biological Survey. CONTENTS. Page. Introduction 1 Methods of taking bird censuses 3 Essentials of a satisfactory census 4 More reports needed on certain areas 6 Results of bird censuses north of Maryland and east of the Plains 6 Results of censuses from southeastern 9 Results of censuses from western States 10 Some notable bird-census results .• 15
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. Washington, D. C. T July 20,1923 REPORT ON BIRD CENSUSES IN THE UNITED STATES, 1916 TO 1920. By May Thacher Cooke, Assistant in Biological Investigations, Bureau of Biological Survey. CONTENTS. Page. Introduction 1 Methods of taking bird censuses 3 Essentials of a satisfactory census 4 More reports needed on certain areas 6 Results of bird censuses north of Maryland and east of the Plains 6 Results of censuses from southeastern 9 Results of censuses from western States 10 Some notable bird-census results .• 15 Relative abundance of certain species 21 Density of bird population 23 Bird life of marshland 24 Bird life of the woodland 27 Scarcity of birds in 1918 28 Birds respond to protection 31 Summary 33 INTRODUCTION. Definite information regarding the number, distribution, and relative abundance of the breeding birds of the United States is greatly desired. Hie Biological Survey started an inquiry for this purpose in the spring of 1914 and sent out circulars to many interested persons throughout the country requesting their. assistance. In addition to the importance of the information desired, because of the value of birds to agriculture, exact knowledge regarding the abundance and distribution of birds was needed in formulating regulations for the protection of game and other migratory birds, the Congress having recently passed laws placing them in charge of the Department of Agriculture. It was also important to ascer- tain what effect the laws then in force had already had on the bird life of the country. The preliminary survey in 1914 proved so satisfactory that the work was repeated the next year on a somewhat larger scale. The results of the work in 19141 and 19152 revealed something of the possibilities of this method of study—that it was a practicable means of obtaining much important and valuable information, and that thereafter it should be a permanent part of the work
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