No. 4.] 



DECREASE OF BIRDS. 



439 



Some reports coine from closely populated regions, where 

 many causes operate to destroy or drive out the birds ; 

 others come from more sparsely peopled regions, where the 

 birds and their natural enemies are not so much interfered 

 with. These personal or environmental differences tend to 

 produce contradictory reports. Where there is conflicting 

 testimony, it must be carefully weighed, and all contradic- 

 tions considered by the one who has to render the final ver- 

 dict. In this, the evidence of those experts who for years 

 have kept careful notes of the number of birds seen should 

 have the most weight. 



A SUMMARY OF REPORTS, BY COUNTIES. 

 Below is a summary, by counties, of the reports regard- 

 ing the gain or loss in numbers of birds in the State for 

 the past ten to forty years. The questions asked were : 



Map of Massachusetts, marked to show the localities from which reports have 

 been received. 



1. Are birds decreasing in your locality, county, or in the 

 State generally ? 



2. How do their numbers compare with those of ten years 

 ago? Three-fourths as many, one-half, one-third, or do they 

 remain about the same ? 



3. Has the decrease (if any) been continuing for twenty, 

 thirty or forty years, or longer ? 



