142 BIRD FRIENDS 



in the heiglit of the nesting-season, when young 

 birds are easily caught, and when most of the harm 

 is done. 



Number of birds killed by cats in Massachusetts. 

 These investigations of Mr. Forbush give data for 

 forming some estimate of the total number of birds 

 killed each year by cats in the State of Massachu- 

 setts. It was found that an average of about one 

 cat per family was kept in towns and nearly three 

 cats per farm in the country, so that we may take 

 two cats per farm as a fair average. There are in 

 Massachusetts 37,000 farms supporting about 74- 

 000 cats. As previously shown, the average num- 

 ber of birds killed by one cat during one month of 

 the nesting-season was 20.4. This multiplied by 

 74,000 gives a total of 1,509,600 birds, probably 

 mostly young birds, killed annually by cats on the 

 farms of Massachusetts, or, in round numbers, one 

 and a half millions. 



We may next inquire what per cent of the total 

 bird population this number comprises. In a bird- 

 census conducted by the United States Bureau of 

 Biological Survey, it was found that there was an 

 average of one pair of nesting birds per acre on the 

 farms of the northeastern United States. In Massa- 

 chusetts there are about 2,800,000 acres of farm- 

 land, which, in accordance with the above census, 

 support 2,800,000 pairs of birds. Assuming that 

 each pair reared two young birds to at least partial 



