COOPER'S HAWK. 193 



ness, where it would seem impossible for it to follow successfully; especially 

 is this the case when chasing 1 some small bird that generally tries to take 

 refuge in such places. It manages, however, with the assistance of its long- 

 tail, which helps it very materially, to turn suddenly and double with re- 

 markable ease, even in dense undergrowth, arresting- its flight instantly, and 

 darting off, perhaps, at a right angle the next second to capture its selected 

 victim. 



The favorite haunts of Cooper's Hawk are moderately timbered districts, 

 interspersed with cultivated fields and meadows, but it is also found in the 

 more extensive and heavily wooded mountain regions, and in the West on 

 the open and almost treeless prairies. It is more or less migratory through- 

 out its range, excepting in the extreme southern parts, where it is perhaps 

 a constant resident. Birds nesting in the northern half of the United St;it<-s 

 I believe migrate regularly, and are replaced by others coming from points 

 still farther north, which would naturally lead to the belief that they were 

 constant residents when this is not the case. 



In the Middle States they usually return from their winter haunts about 

 March 15, and by the end of the month they are located again on their breed- 

 ing grounds, which are generally resorted to from year to year by the same 

 birds, if not persistently disturbed. 



As a rule I believe a new nesting site is selected each season at no 

 great distance from that of the previous year, but occasionally the old one 

 is resorted to for successive seasons. In the choice of these, old Crows' 

 nests when available are given the preference, but larger Hawks' nests, as 

 well as those of squirrels, are frequently used. When they build nests of 

 their own they are usually placed between the diverging limbs in a crotch 

 of the tree or saddled on some smaller limb close to the trunk. This last 

 is most often the case when they nest in thick and bushy conifers. No 

 preference seems to be given to any particular kind of tree, and their nests 

 are generally found at no very great height from the ground, ranging from 

 20 to 50 feet up, rarely lower or higher. 



Their nests vary considerably in bulk, according to the locations in 

 which they are placed, and are composed of sticks lined with finer twigs, 

 and scattered among these are generally found small scales and flakes of the 

 outer bark of different species of trees, those of the yellow pine being pre- 

 ferred when obtainable. Nests built by the birds themselves compare favor- 

 ably with those of other Raptores. 



On the plains, where, from scarcity of suitable timber elsewhere, they 

 are confined to the shrubbery of the creek bottoms, consisting mainly of 

 cottonwoods and willows, they sometimes nest as low as 10 feet from the 

 ground, and I have here found some of their nests fairly well lined with the 

 dry inner bark of the eottonwood and with weed stalks; while in the vicinity 

 of Grand Forks, North Dakota, according to information furnished me by 

 Mr. Gr. Or. Cantwell, they are said to nest occasionally directly on the ground. 

 26957 Bull. 1 13. 



