UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1165 



Washbglon, 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 States.. 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. The 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 1914^ and 1915^ 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 of the Bio- 

 logical Survey. As there are no funds available for this kind of 

 work, it depends entirely on the cooperation of volunteer observers. 



1 Bull. 187, U. S. Dept. Agr., Preliminary census of the birds of the United States. 1915. 

 » BuU. 396, U. S. Dept. Agr., Second annual report of bird coxmts in the l^Uted States, with discussion 

 of results. 1916. 



44125— 23— Bull. 1165 1 



