284 ANIMAL LIFE IN THE YOSEMITE 



The legs of the Sharp-shinned Hawk are very long and slender, and 

 bare of feathers almost to the top of the tarsus, while the claws are slender 

 and very sharp. These are all adaptations of use in grasping the feathered 

 prey. 



Cooper Hawk. Accipiter cooperi (Bonaparte) 



Field characters. — Similar in all respects to Sharp-shinned Hark (which see), except 

 that size is about double and end of tail is distinctly' rounded (pi. 44^). Voice: Of 

 adults a rather harsh kluk, klulc, TcluTc, Mule; of young a shrill quick, quick, quick, many 

 times in rapid succession, and also a far-carrying swee'-ew or psee'-ur. 



Occurrence. — Moderately common resident, chiefly in Upper Sonoran and Transition 

 zones, on both slopes of Sierra Nevada. Partial to growths of tall trees in vicinity of 

 streams. Observed up to 7700 feet (Dark Hole) on the west slope and to 8000 feet 

 (Walker Lake) on the east side. 



The Cooper Hawk is a larger replica of the Sharp-shinned Hawk in 

 both form and structure, and it also closely resembles its smaller congener 

 in habits. Its greater size enables it to prey upon larger birds such as 

 quail and young grouse, but it is guilty of killing all manner of smaller 

 birds as well, even down to those of the size of the Yellow Warbler. 



In flight the Cooper Hawk exhibits the rounded wings and the relatively 

 long tail characteristic of the bullet hawks {Accipiter and Astur), but the 

 end of its tail is slightly rounded, a character which serves well to dis- 

 tinguish it from the Sharp-shin. (See pi. 44.) It also indulges in more 

 soaring and circling during flight than its smaller relative. From the 

 Goshawk it differs in much smaller size as well as in its brown rather than 

 gray effect of under surface. 



As indicative of the stealthy nature of the Cooper Hawk, we recite 

 our experience with a family of these birds. In the course of our field 

 studies on the floor of the Yosemite Valley, we many times passed a dense 

 stand of young yellow pines and black oaks situated between the foot 

 of the Yosemite Falls trail and the Ahwahnee footbridge. We did not 

 note anything there, however, except the usual assemblage of small 

 songsters. But on the morning of July 25, 1915, 3 young Cooper Hawks 

 were discovered in this thicket. Their characteristic calls drew our atten- 

 tion, and we located the birds through finding a large amount of white 

 excrement spattered about on the ground and shrubbery. This excrement, 

 moreover, gave a decisive clue to the situation of the forsaken nest over- 

 head. The thicket of trees had been passed repeatedly during the preceding 

 six weeks by members of our field party while searching for nests of small 

 birds without our once catching sight of the old hawks, who must of course 

 have been going to and fro many times a day. 



The nest was about 60 feet up in a tall slender black oak growing in a 

 dense thicket of oaks and pines about a hundred feet from a small meander- 



