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 (pl. 44d). 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 observed 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 individuals 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 (pl. 44d). 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 least glint of sunlight on the adult eagle's head and neck shows these parts to have a golden brown color unlike that of either the Vulture or the Red-tailed Hawk.

Golden Eagles are seen singly or in pairs; we have never seen more than two at any one time. The birds are wary, by nature as well as by necessity, and in consequence are rarely seen at rest. In flight they exhibit well the strength and power with which an eagle is so closely associated in the average person's mind. Sometimes they are seen to dash across or down a cañon in direct course as if going on a particular mission; again, and more often, they circle with apparent leisure, presumably on watch for prey; and occasionally they spiral up until in spite of their large bodies and broad wings they become mere specks in the sky, seeming to move scarcely at all. In Mono Pass, where the west wind often sweeps through the cañon with such force as to impede the progress of man or animal, a Golden Eagle was seen one day flying against the gale and even he was forced to tack back and forth, seeking a low course behind sheltering crags.

Twice only did we chance to see an eagle perched. In Yosemite Valley on November 9, 1915, after the first fall of snow, a bird alighted on the dead top of a tall pine about 200 yards away. As it grasped the branch, masses of snow, dislodged by the impact of the bird's weight, went showering down through the tree, glittering in the brilliant sunshine. With our field glasses we saw clearly the golden brown tint of the bird's upper plumage.

On the morning of May 19, 1919, while we were driving along the floor of the Valley near Cathedral Spires, a large shadow passed over the road. Looking up we saw a Golden Eagle. The bird alighted in the top of a not distant dead tree where we could see to advantage its characters of size, feathered head, and dark coloration.

At Pleasant Valley we had several conclusive demonstrations that the eagle's reputed keenness of vision is no idle proverb. Several times during our stay, a year-old captive in a cage at the store near by was heard to give its loud clear call. Looking up we would sooner or later detect one or two eagles above the hill-rimmed horizon. Sometimes the approaching birds looked to be mere specks in the sky, too small to attract our attention until it was directed to them by the obvious excitement of the captive; often it was several minutes before they came close enough for us to distinguish them from the ever present Turkey Vultures. But the caged bird had recognized his kind the instant they hove into sight. We were told that this captive bird had been taken in 1914 from a nest in a big digger pine east of the settlement, and that another young eagle in the nest at the same time had been killed accidentally while the tree was being felled.

We have no information concerning the food of the Golden Eagle in the Yosemite region; but we surmise that this bird of prey takes toll from a number of the medium-sized kinds of mammals. The captive bird at Pleasant Valley afforded us an opportunity to learn something of the manner in which an eagle handles its food. When offered a dead ground squirrel this eagle seized it in one foot, dragged it about in the earth at the bottom of the cage for several minutes and then began to eat it. It dug into the squirrel's skull with its strong beak, tore it apart and swallowed the fragments bone and all. The skin and hair were eaten with avidity, but the entrails were carefully avoided.