6± Wyoming Experiment Station. 



emy except man. As Audubon was passing down the Ohio 

 he observed one of these Hawks dive into a flock of grackles 

 which was crossing the river, and kill four or five of them. 

 After giving each, victim a fatal squeeze the Hawk allowed it 

 to fall to the water and at the close of the chase returned and 

 picked up all from the surface." 



337 a. Buteo borealis kriderii Hoopes. 

 Krider's Hawk. 



Summer resident ; uncommon. A. O. U. check list re- 

 fers this species to Wyoming and probably some of the early 

 reports on Red-tail Hawks should also be included. Cary 

 found three of these birds near Newcastle in the summer of 

 1899. The food habits of this species will be referred to un- 

 der the Western Red-tail, which is a close ally. 



337b. Buteo borealis calurus (Cass.). 

 Western Red-tail. 



Summer resident ; abundant, and a few may remain all 

 winter. In Wyoming this bird is seldom seen about a ranch, 

 as it depends almost entirely upon small mammals for food. 

 The records from all parts of the United States prove that it 

 is not seriously detrimental to the farm yard. The greater 

 portion of the records cited concerning its food have been col- 

 lected in thickly settled agricultural districts, when from ne- 

 cessity they occasionally visit the poultry yard. This and 

 the allied species should be especially protected in Wyoming, 

 where they feed largely upon prairie dogs, ground squirrels 

 and mice, which are, taken as a whole, very detrimental to 

 farmers and ranchmen. Fisher in discussing their food habits 

 says (Hawks and Owls of the United States, pp. 49-50) : 



"Meadow mice seem to form the staple article of its food, 

 although at times other species of mice, arboreal and ground 

 squirrels, rabbits, or an occasional mole or shrew are found 

 among the stomach contents. This Hawk and its allied species 

 render valuable service in reducing the number of ground 



