CHANGES IN THE NUMBERS OF BIRDS 125 



to whether birds are changing in numbers. The 

 first census was taken in 1914. During the nesting- 

 season of that year a census was taken by several 

 hundred observers on farms situated in different 

 parts of the United States, but chiefly in the north- 

 eastern section. These reports showed that there 

 was an average of one pair of birds to the acre. At 

 this rate there would be about 350,000,000 pairs of 

 adult birds on the farms east of the Mississippi 

 River. The following quotation is taken from a cir- 

 cular describing the census : 



That the present bird population is much less than it 

 ought to be, and much less than it would be if birds were 

 given proper protection and encouragement, is the most 

 important deduction from this preliminary census. An 

 approximate average of one pair of birds to each acre of 

 land was found, but individual censuses showed that it 

 is possible, under strictly farm conditions, very largely 

 to increase this number. Near Wellington, Virginia, a 

 tract of forty-nine acres of a dairy farm, of rather less 

 than the average of ploughed ground, supported a bird 

 population of one hundred and thirty-seven pairs, or three 

 pairs to the acre. On a forty-acre farm in Rantoul, Kan- 

 sas, after fourteen years of bird protection and encourage- 

 ment, there were found one hundred and fifty-seven pairs 

 of birds, or about four pairs of birds to the acre. 



It is evident from the foregoing statement that double 

 the present bird population is easily obtainable, while 

 a threefold increase is well within the possibilities. 



It was noticeable that the blocks most thickly in- 

 habited by people were also most fully occupied by 

 breeding birds. This is a striking refutation of the wide- 

 spread belief that human beings and birds are naturally 



