348 BOARD OF AGRICULTURE. [Pub. Doc. 



be far less injury to the birds than in the spring. Those who 

 prefer not to spray can usually find other methods for jDro- 

 tecting their trees against these insects. The cutting of 

 undergrowth and trees and the trimming of trees is often 

 found necessary in suppressing the gypsy moth ; but it should 

 not be done in spring and summer, when the birds are nest- 

 ing, except in cases of extreme necessity. 



Some Facts about tpie Natural Enemies of Birds. 



A great deal has been said and written of late regarding 

 the natural enemies of birds and game. Undoubtedly such 

 enemies form a most potent check on the increase of birds' 

 numbers, and where for any reason birds are decreasing in 

 numbers, it may become necessary to destroy their natural 

 enemies. Foxes, weasels, minks, skunks, squirrels and 

 crows will need close watching at times, lest they become too 

 numerous. The two common species of bird hawk, the 

 cooper's hawk and the sharp-shinned hawk, are everywhere 

 very destructive to birds ; but the two natural enemies of our 

 birds that seem to exceed all others in importance are the 

 domestic cat and the so-called English sparrow. 



Our native birds had enemies enough to keep them well in 

 check before these destructive foreign species were introduced 

 here. Individually, the cat and the sparrow are not so de- 

 structive as the bird hawk, but the destructiveness of a species 

 increases as its numbers increase. Possibly every bird hawk 

 eats on the average 2 small birds a day, or Y30 birds a year, 

 while only the adult cats in good hunting ground will average 

 50 birds a year each ; but in the State at large there are 

 probably at least 150 cats to every bird hawk, and provided 

 that these 150 cats average only 10 birds apiece in the year, 

 they would destroy 1,500 birds to Y30 killed by the hawk. 

 Proof of the destructiveness of cats was secured in my ex- 

 plorations of tern colonies along the Atlantic coast during 

 the past summer. On Penikese Island there was one vagrant 

 cat running wild ; here and there young terns could be seen 

 with their heads torn off. I was informed by the superin- 

 tendent of the hospital on the island that this was the work 



