292 ANIMAL LIFE IN THE YOSEMITE 



The Ferruginous Rough-legged Hawk is, or was under original con- 

 ditions, a common winter visitant to the plains of central California and 

 to the larger open tracts in the foothill country, individuals perching in 

 low trees and also often upon the ground. It has been called aptly the 

 California Squirrel Hawk, in recognition of its custom of perching upon 

 squirrel mounds in the prairie country and of preying upon the ground 

 squirrels. 



In general form the Rough-leg resembles the well-known Red-tail. It 

 is slightly larger and its coloration is somewhat different. There is no 

 red on the tail of the Rough-leg at any age, and the base of that member 

 shows a considerable amount of white, easily seen when the bird is in flight. 

 The whole under surface of the body in the Rough-leg is white with scat- 

 tered small streaks of brown which, however, are not apparent at any 

 distance. At close range, or with a specimen in hand, the lower part of 

 the leg (tarsus) clear to the toes is seen to be covered with feathers more 

 or less marked with brown or rusty. 



Golden Eagle. Aquila chrysaetos (Linnaeus) 



Field characters. — Typical of bird of prey; largest of Sierran land birds (length 30 

 to 35 inches, spread 6 to 7 feet). Coloration chiefly dark brown, becoming paler, more 

 golden brown, on top and back of head; a grayish white area at base of tail except in 

 old birds, and a whitish area on under side of each wing toward extremity (pi. 4Ad). 

 Voice: A single loud cry, sometimes repeated several times in quick succession. 



Occurrence. — Moderately common resident in foothill belt (Upper Sonoran Zone) 

 and at middle levels of the mountains (Transition Zone) on west slope of Sierra 

 Nevada; in summer observ^ed at many points elsewhere in the region east to the Sierran 

 crest in vicinity of Mono Pass. 



Among Sierran land birds the Golden Eagle is supreme in size and 

 in majesty. It is an inhabitant of the hills and mountains and only rarely 

 strays out into the plains to the west; nor has it been found eastward in 

 the Yosemite section much beyond the crest of the Sierra Nevada. We 

 found the species most common in the western foothill belt, where indi- 

 viduals were seen almost daily ; in the higher mountains we observed them 

 less frequently, probably because in this territory a larger forage area is 

 necessary to each individual. 



The Golden Eagle may easily be distinguished from the few other birds 

 of prey which approach it in size. The light patch usually present at 

 the base of the tail, and the subterminal light areas under the wings, are 

 readily seen at a moderate distance when the eagle is in flight (pi. 44fZ). 

 The tips of its big primary feathers are rarely spread apart in the manner 

 of a Turkey Vulture, nor are its wings, as seen from in front or behind, 

 inclined upward in the fashion common to the Vulture. Moreover, the 



