SIERRA NEVADA MOUNTAIN SHEEP. Ovis canadensis sierrae Grinnell

Mountain Sheep or Bighorns originally inhabited the higher slopes and ridges of the Yosemite region in numbers. To the south of the Yosemite section, in the vicinity of Mammoth Pass and thence south to the neighborhood of Mount Whitney, these animals still exist in moderate numbers, but elsewhere in the Sierra Nevada they are things of the past. The rush of white men to the mines of Tioga and Mammoth doubtless resulted in many mountain sheep being killed for food; and later, when domestic sheep were run into the mountains, it is known that the herders levied toll on all the wild game to the limit of their hunting equipment; so we may believe that they had a hand in the reduction of the native sheep. Some of the killing of mountain sheep is to be laid to persons hunting for sport, but such killing was probably a minor factor in their reduction in the Yosemite region. Whatever the several agencies were, the fact remains that mountain sheep, once well represented in the mountains of the Yosemite region, are now entirely gone, with only faint prospect for return, by gradual reinvasion from the more southern parts of the Sierra Nevada or by introduction.

John Muir in his Mountains of California (1894, pp. 308-324) tells of meeting with a flock of 25 or so mountain sheep on the headwaters of the San Joaquin River near Mounts Emerson and Humphrey, in the autumn of 1873. He also tells of finding a weather-whitened skull on the slopes of Mount Ritter. The only reference by him to wild sheep in the Yosemite region proper is to a band of three "discovered snow-bound in Bloody Cañon a few years" previously to 1874 and "killed with an ax by mountaineers, who chanced to be crossing the range in winter."

One of the men who served us as packer in 1915, Mr. George Smith, told a member of our party that he saw mountain sheep in the summers of 1876 to 1878 on the eastern slope of Sonora Pass, which is at the junction of Alpine, Mono, and Tuolumne counties. During each one of these years he would see about a dozen sheep. This location is some miles north of the present boundary of the Park. Jim Bartel, a resident of Yosemite Valley, stated that sheep had not existed in the Park since his coming there in 1893. We may thus conclude that sheep probably occurred within the territory at present included in the Yosemite National Park until some time in the seventies or possibly the early eighties. Occasional individuals may have wandered in after that time. One resident of the region told us in 1915 that he believed that sheep were then still present in the territory north of the Park; but of this we have no further evidence.

The skull of the mountain sheep, particularly that part of the head which bears the massive bony horn cores and the horns, is very thick and solid so that when exposed to the elements it disintegrates slowly. Conditions along the crest of the Sierras are conducive to long persistence of such relics (fig. 36b). There are few or no rodents to gnaw at the bones as they would in lower altitudes, and the climatic conditions are also favorable. The winter snow packs the bones in 'cold storage' for long periods of time. Hence, such relics, when found by naturalists, merely indicate that sheep once occurred in the region; no close estimate can be formed of the time which has elapsed since the particular animal represented by the relic lived there.

Three fragments of this sort came to attention in 1915. Mr. Forest S. Townsley of the Park Ranger Service discovered the frontal portion of a mountain sheep skull on the slopes of Mount Dana. The senior author, on September 6, 1915, while descending the upper slopes of Parsons Peak, came upon a weathered horn and a portion of a skull in a grassy place at about 11,500 feet altitude. Later, on September 24, he discovered another relic toward the head of Warren Fork of Leevining Creek, at about 9500 feet altitude. This fragment was partially buried in the gravelly surface of a sagebrush-covered slope.

The best specimen of mountain sheep from the Yosemite Region which has come to light is a skull of a big ram, with horns, all in good condition, killed somewhere east of Crescent Lake, at an unknown date (fig. 36a). This trophy was for many years in the possession of Mrs. John S. Washburn of Wawona, and from her it passed, in 1920, to the California Museum of Vertebrate Zoology. The measurements of this specimen, as compared with those of a ram of the domestic sheep (fig. 36c), are given in the following table. Both animals, as judged from the growth-rings of the horns, were eight years old. The vastly greater basal circumference of the horn of the wild sheep is the outstanding feature of difference.

The mountain sheep is a large animal, with a body somewhat like that of a deer, but with horns resembling in general structure those of a domestic sheep. The name 'Bighorn' has reference to the size of the horns in the male. Both sexes in the mountain sheep bear horns, although those of the ewes (females) are much smaller, flatter, and less curved than those of the males; they are goat-like. A full-grown sheep of the Sierra race (as shown by specimens from Mount Baxter, farther to the south) stands about 3 feet high at the shoulder and weighs in the neighborhood of 200 pounds. The body is densely covered with long crinkly hairs at the bases of which there is a minute 'wool' (underfur). The color of the pelage is pale sandy brown, with a large whitish patch on the rump.

Fig. 36. (a) Skull and horns of male Sierra Nevada Mountain Sheep obtained east of Crescent Lake many years ago; the "Washburn" specimen (top). (b) Weathered fragments of Mountain Sheep skulls and horn picked up by the senior author on Parsons Peak and on Warren Mountain in 1915 (middle). (c) Skull and horns of male Domestic Sheep (bottom). All about 1/10 natural size.

The wild sheep of the Sierra Nevada under original conditions occupied for the most part the highest and wildest parts of the mountains, the Alpine-Arctic Zone and adjacent parts of the Hudsonian Zone. In these high places they subsisted on the native bunch grasses and other small plants to be found there. In the winter time the animals sometimes moved down the east slope of the Sierras to where the snow mantle was not so deep, but there was no general exodus as in the case of the Mule Deer. The Sierra Nevada Mountain Sheep was a hardy animal, fitted to live in the narrow belt of alpine conditions found along the crest of the Sierras, and would be there in numbers today had it received any reasonable consideration from the white man. Its gradual return, from the southern remnant, is a thing to be hoped for.