THE OREGON SPORTSMAN 79 



A NATIONAL BIRD CENSUS 



How the Biological Survey of the Department of Agriculture 



Expects to Work Toward a Rational Basis for 



State and Federal Laws 



BY 



HENRY W. HENSHAW 



Chief Biological Survey, Washington. D. C 



The passage of the Federal law placing migratory game and 

 insectivorous birds in charge of the Department of Agriculture 

 makes it desirable to obtain more detailed and definite informa- 

 tion concerning the distribution of bird life in the United States, 

 and for this data we must look mainly to voluntary observers. 

 This bureau desires to obtain a series of bird censuses, beginning 

 with last summer (1914), taken during the breeding season, with 

 a view to ascertaining how many pairs of each species of birds 

 breed within definite areas. Such censuses will serve as a basis 

 for determining later whether the present state and Federal laws 

 are effective and whether game and insectivorous species are in- 

 creasing or diminishing in numbers. In this undertaking you can 

 materially aid by taking a census of the birds breeding this 

 summer on some area or areas selected to fairly represent the 

 average character of the country in your immediate neighbor- 

 hood. The ideal tract of land would be one that exactly repre- 

 sents the average conditions of the neighborhood in the propor- 

 tions of woodland, plowed land, meadow, etc., contained in it. 

 As this idea is practically unattainable, an area should be selected 

 representing fairly average farm conditions, but without wood- 

 land. It should not be less than 40 acres — a quarter of a mile 

 square — nor more than 80 acres, and should include the farm 

 buildings, with the usual shade trees, orchards, etc., as well as 

 fields of plowed land and of pasture or meadow. 



The area should be selected not only with reference to the 

 present summer's work, but should, if possible, be chosen so that 

 the physical conditions will not be much changed for several 

 years; if succeeding annual censuses show changes in the bird 

 population, it will be known that they are not due to changed 

 environment. 



What is wanted is a census of the pairs of birds actually 



