HAWKS AND FIELD MICE. 43 



Hawks. — Though hawks are our most common birds of prey, 

 many kinds are too rare to exert a marked effect, either injurious or 

 beneficial, upon the interests of the farmer; but the most common 

 kinds are widely distributed and their voracious appetites make them 

 of considerable economic importance. Nearly all hawks feed more 

 or less upon rodents, and their most frequent victims are the short- 

 tailed field mice. 



The marsh hawk, or harrier {Circus hudsonins)^ is probably the 

 most common and most widely distributed North American species. 

 It is of medium size and may easily be recognized, while flying low 

 over fields and meadows, by its conspicuous white upper tail coverts. 

 The I'esults of an examination of 124 stomachs of this species are as 

 follows: Seven contained poultry or game; 34, small birds; 57, mice; 

 22, other mammals; 7, reptiles; 2, frogs; 14, insects; and 8 were 

 empty. Field mice were positively identified in 44 stomachs, averag- 

 ing almost two to each stomach. Eight were found in one stomach. 

 The other mammals were mainly ground squirrels (spermophiles) 

 and rabbits. 



The buzzard hawks (genus Buteo) include seven species and six 

 subspecies, all ratlier large and slow of wing. They are rarely able 

 to capture a domestic or wild fowl. They live chiefly on small mam- 

 mals, insects, snakes, and batrachians. The group includes such well- 

 known birds as the red-tailed hawk {Buteo horealis and four sub- 

 species), red-shouldered hawk {Buteo lineatus and two subspecies), 

 Swainson hawk {Buteo swamsoni), and broad-winged hawk {Buteo 

 2)latypterus). 



A summary of the food of 502 red-tailed hawks is as follows: 

 Fifty-four of the stomachs contained poultry or game birds: 51, 

 other birds; 278, mice; 131, other mammals; 37, batrachians and rep- 

 tiles; 47, insects; 8, crayfish; 1, centipedes; 13, offal; .and 89 were 

 empty. Two hundred and twenty-eight stomachs contained 350 field 

 mice. 



Of 220 stomachs of the red-shouldered hawk 3 contained poultry; 

 12, other birds; 102, mice; 40, other manmials; 20, reptiles; 39, batra- 

 chians; 92, insects; IG, spiders; 7, crayfish; 1, earthworms; 2, offal; 

 3, fish; and 14 were empty. Sixty-three stomachs contained 89 field 

 mice. 



Of Swainson hawks, 18 stomachs were examined. Of these 7 con- 

 tained small mammals; 8 contained insects; 3, reptiles; 3, batrachians; 

 and 3 were empty. One of the mammals was a mouse, and nearly all 

 the insects \vere locusts and grasshoppers. Throughout its sunnner 

 range this species lives almost entirely upon grasshoppers. 



Of broad-winged hawks, G5 stomachs were examined, 15 of which 

 contained mice, and b) other small mannnals. Xo poultry or game 

 birds were found iu the stomachs, and the chief food was insects. 



