52 THE IMPORTANCE OF BIRD LIFE 



of statistics, especially from the northeastern 

 States. The Survey averaged up the various 

 figures and estimated the number of resident birds 

 to the acre. In the following year the experiment 

 was repeated, and it soon became an annual event, 

 care being taken to correlate the yearly reports 

 from the same areas. Soon the Biological Survey 

 was satisfied beyond a doubt that it had hit upon 

 the proper method for taking a census. Each 

 annual report virtually coincided with that of the 

 previous year. 



The reports were most numerous in the north- 

 eastern States, and so often have the counts there 

 been taken that there can be no hesitancy in vouch- 

 ing for their correctness. Each farm, then, 

 in New England, New York, and New Jersey con- 

 tains about one and a third pairs of nesting 

 birds to the acre. The population of the forests 

 is about the same. Thus in New York State 

 there are roughly sixty million native birds 

 and from seventy-five to eighty million in New 

 England. These, it must be understood, are only 

 the resident population, birds that nest there, 

 while several times that number pass through 

 during the year on their migrations. Accord- 

 ing to these figures there are several billion 

 birds residing in the United States without 

 counting those which visit Canada and Green- 

 land. 



The most numerous of all birds in the East is 



