SIERRA NEVADA GOLDEN-MANTLED GROUND SQUIRREL Callospermophilus chrysodeirus chrysodeirus (Merriam)

Field characters.—Size of body about two-thirds that of House Rat; tail about half length of head and body. Head and body 5-3/4 to 7-2/3 inches (147-195 mm.), tail 2-5/8 to 4 inches (67-102 mm.), hind foot 1-1/2 to 1-3/4 inches (38-43 mm.), ear from crown 2/5 to 4/5 inch (11-20 mm.); weight 4-3/4 to 8-1/2 ounces (135-239 grams). Whole head and neck yellowish or coppery red (pl. 2); on each side of back a broad white stripe bordered above and below by broad black stripes; middle of back grizzled brown; sides and under surface of body pale gray or whitish; tail black centrally, buffy at margin, cinnamon on under surface. Workings: Holes in ground 2 to 2-1/2 inches in diameter, usually close to rocks or logs.

Occurrence.—Common resident in Canadian and Hudsonian zones on both slopes of Sierra Nevada. Recorded from Aspen Valley, Merced Big Trees, and near Chinquapin, eastward to Warren Fork of Leevining Creek and to Walker Lake. Lives on ground in open forest and also in rocky situations. Diurnal.

The Golden-mantled Ground Squirrel is one of the most conspicuous members of the high mountain fauna, for it is the most brilliantly marked of all the local squirrel tribe. People living in the mountains usually term this species the "copperhead" or yellow-headed chipmunk, both of which names are appropriate as applying to the coloring on the head and shoulders (pl. 2). In general ecology this squirrel is the high-mountain counterpart of the well-known California Ground Squirrel of the lowland valleys and foothills.

In size the copperhead is our smallest ground squirrel. It is about three-fourths the size of the Belding Ground Squirrel and only one-third or one-fourth the size of the California Ground Squirrel. It is larger, however, than any of the chipmunks. Its general appearance, with stout body and short tail, readily classifies it as a terrestrial squirrel rather than as a climber.

The range of the copperhead practically coincides with that of the lodgepole pine; yet the squirrel is in no way dependent upon this tree directly. The lowest station of record for the "callo," as members of our party got in the habit of calling the animal for short, is at Merced Grove Big Trees, altitude 5500 feet, a place which also marks the western limit of its range. Across the Sierras the whole of the Canadian and Hudsonian zones is inhabited, eastward to Walker Lake; sparingly to Mono Craters. On the high peaks this species does not seem to go much above timber line. Thus, on Mount Florence, the last individual was seen at 10,700 feet, which was just above the highest stunted white-bark pines. On one occasion, at Gaspipe Spring, east of Mono Mills, one of these squirrels was come upon on the ground in the sagebrush, "miles from any timber."

The main habitat or niche of this squirrel is the open rock-strewn floor of the sparse lodgepole pine forest. It keeps closely to this sort of environment, while the Belding Squirrel inhabits the open meadows. At the margins of the meadows, however, the two are often seen in association. The "callo" is strictly a ground dwelling animal. When it wants to look about, it may go to the top of a low boulder or of a log. Only once did we catch sight of one in a tree, and that individual when frightened ran down to the ground and quickly sought its burrow.

The "callo" when first met with is rather shy and usually scampers to the vicinity of its burrow, where it sits hunched up, like a California Ground Squirrel, ready to dart into its underground retreat at an instant's further warning. But its confidence can be won; about camps it may be studied at close range. The gait when running is heavy, with little or none of the bounding or skipping movements of chipmunks. On rare occasions a "callo" will assume the upright picket-pin posture so characteristic of the Belding Ground Squirrel.

The "callo," quite in contrast with the other local squirrels, is seldom heard to utter notes of any sort. On one occasion, near Lake Tenaya, one of these animals was heard to give a high-pitched squeak, repeated three times. In mating chases, when a male pursues a female, low grunting and squeaking notes are uttered; but these are inaudible beyond a few feet.

The Golden-mantled Ground Squirrel spends the winter months, when snow covers the high mountains, in hibernation. Exact data on time of emergence and disappearance are lacking. When we reached Peregoy Meadow on May 20, 1919, the animals were already abroad. At Aspen Valley they were out as late as October 18 (1915). Probably they stay out until the first big storm of the season, which snows them in for the winter.

The summer season is occupied by these squirrels in rearing their broods and in obtaining forage for themselves, not only for their daily needs, but also enough to permit of their acquiring the fat necessary for warmth and sustenance during the long winter sleep. Of one animal collected at Ten Lakes on October 9, 1915, the collector notes that "at least a handful of fat" was removed from the inside of the skin. Not all the individuals, however, acquire fat in equal amounts. Thus, of two males taken on October 3 and 9, respectively, one weighed about 5 ounces (138.5 grams), the other 7-3/4 ounces (218 grams). And of two females taken at Aspen Valley on October 16, 1915, the respective weights were 5-1/2 ounces (156.5 grams) and 8-1/2 ounces (239 grams).

Once a "callo" was seen to take a dust bath. At Crane Flat, on June 16, 1915, one of our party was resting in a sandy place where large boulders were scattered about. At his approach all the squirrels had disappeared; but after a time one—a Golden-mantled—came forth, frisked about, and repeatedly "dived through" the little heaps of sand; but it did not roll in the sand. Ground squirrels, generally, are afflicted with fleas, and this and other species have been seen to take this method of ridding themselves of these parasites.

About camping and lunching places where summer tourists drop food scraps, copperheads often take advantage of the opportunities afforded to make the getting of food an easy matter. On the summit of Clouds Rest, on August 25, 1915, a "callo" was seen which would come to within three feet or less of a person and take tidbits thrown on the ground. When one of our party offered more material than the squirrel could consume at the moment, it carried the food (in this case dried fruit) in its mouth some distance off, dug a hole in the ground, using the forefeet, thrust the object into the little excavation, then covered the place with earth again, after which it poked small loose stones over the site so as to further disguise it. Probably, as in the case of the California Jay, these caches are temporary affairs, the food being dug up again after a short time and eaten. At Merced Lake four of these squirrels were noted on one occasion gleaning grain scattered on the ground where horses had been fed.

The nest of this species is placed in the ground. At Merced Grove one individual had its burrow in open ground close to several tents. At Crane Flat several of the animals were seen to disappear into burrows surrounded by low brush plants. In the higher altitudes many had their burrows on the open floor of the lodgepole pine forest, sometimes, but not always, beneath rocks. Unfortunately we did not dig out any burrows of this species and no one else seems to have done so in the region, so we know nothing as to the arrangement of the burrow system. Presumably it does not differ greatly from those of the California and Belding ground squirrels; if anything, it might be expected to be simpler in plan.

The animal which had its burrow at Merced Grove was seen to choose as nest material some brown wrapping paper which had been left nearby. This was torn into small pieces by use of both the teeth and forepaws and stuffed into the cheek pouches. Then the squirrel disappeared into its burrow, doubtless to add the paper to the lining of the nest chamber.

Like the other local squirrels the Golden-mantled Ground Squirrel has only one brood a year; this brood is produced in the early part of the summer season. Females containing embryos were taken in 1915 on June 12 (two on this date), 14, 26, and 28, the numbers of embryos in these instances being 2, 5, 6, 6, and 5, respectively. The young stay below ground until about one-third to one-half grown. Mr. Dixon saw numbers of young of this species on the east slope of the Sierras above Mono Lake Post Office between altitudes of 7000 and 7800 feet on July 5, 1916.

Only one bit of information regarding the enemies of the "callo" was obtained. The droppings of a Mountain Coyote on Colby Mountain were found to contain hair of this species.