Part II.] NATURAL ENEMIES OF BIRDS. 241 



stance by such an increase of grubs and grasshoppers as to 

 destroy the grass crop over large areas, and it would be very 

 unwise to allow the extirpation of this bird. 



Hawks and Owls. 



Many hawks are not only useful in nature as regulators of 

 mammal life but they are beneficial to the farmer by destroy- 

 ing grasshoppers and other large insects, squirrels, rats and 

 mice. Among the most useful of all is the rough-legged hawk 

 (Archibuteo lagopus sancti-johannis) , which very rarely has been 

 known to kill birds, and never, so far as known to me, to molest 

 poultry. The species is large, flaps and sails rather slowly, and 

 thus makes a good mark for a shotgun, or, sitting upon a dead 

 tree or stake, furnishes an excellent target for a rifle. Many are 

 shot annually in fall, winter or spring, mistaken for "hen hawks." 

 The number of mice killed by these birds is enormous, and the 

 shooting of the species is a serious detriment to agriculture. 

 Nevertheless, farmers often boast of the number that they have 

 killed and gunners shoot them at every opportunity. They 

 would much better devote their energies to shooting vagabond 

 cats, which do far less good and much more harm. 



One can hardly write of the economic relations of hawks 

 and owls in this country without referring to the work of Dr. 

 A. K. Fisher of the Biological Survey. During his researches he 

 has examined the contents of more than two thousand seven 

 hundred stomachs of these birds, with the result that out of 

 the seventy-three species investigated only six in all the United 

 States were found harmful, and all the rest were classed as bene- 

 ficial. Omitting the six species that feed largely on poultry and 

 game, two thousand two hundred and twelve stomachs were 

 examined, 56 per cent of which contained mice and other small 

 mammals, 27 per cent insects, and only 3| per cent poultry or 

 game birds. Of the six harmful species, three are so rare that 

 they have little effect, and in New England only two, the 

 cooper's hawk {Accipiter cooperi), and the sharp-shinned hawk 

 (Accipiter velox), are really common and generally injurious.^ 



1 The goshawk (Aatur atricapillus atricapillus), the duck hawk {Falco peregrinu8 analum), and 

 the pigeon hawk (Falco columbarius columbariua) are exceedingly destructive to birds, but are 

 uncommon in Massachusetts. 



