Natural History of the Ground Squirrels of California/Stephens Soft-haired Ground Squirrel
STEPHENS SOFT-HAIRED GROUND SQUIRREL.
Citellus mollis stephensi (Merriam).
Other names.—Stephens Spermophile; Picket-pin, part; Stephens Ground Squirrel; Spermophilus mollis stephensi.
Field characters.—Small size combined with very short and slender tail and gray coloration (no stripes or special markings); ear small; length of body alone about 6¼ inches, with tail about 2 inches more.
Description.—Nearly full-grown young in summer pelage (June): General tone of coloration on upper surface of body, buffy gray; top of head from nose to hind neck, pale cinnamon-buff, deepest on nose, and changing into color of back on shoulder; cheek to shoulder, olive-buff; eyelids white; whiskers black; back light drab with a faint effect of fine dappling; the hairs on the back lead-colored at extreme bases, then gray, then bister, and tipped with buffy white. Upper surfaces of feet dull white; palms naked; soles of hind feet clothed with dull whitish hairs to about halfway forward from heel; claws blackish, with horn-colored tips. Tail flat-haired, but narrowly so, and tapering from base to tip; upper surface buffy drab; beneath dull white at base, becoming dusky pinkish buff toward end. Lower surface of body silvery white, faintly buff tinged, particularly as forming a band along each side, and with much of the leaden-hued bases of the hairs showing through.
We have at hand but two specimens of this ground squirrel, and these are both immature.
Color variations.—A considerable series of specimens of Citellus mollis (subspecies?) at hand from northern Nevada make it seem likely that stephensi varies in color but little from the coloration as here described; probably old adults are grayer, with little or none of the cinnamon-buff about the head. The summer pelage at all ages is notably soft and silky as compared with that of most other species of ground squirrels at the same season. There is possibly a distinct winter pelage, with regular molts in spring and fall; but we have no specimens to indicate this.
One of our two specimens has the tail much flatter, and broader ended, than the other; but this we think is due to the way the tail was wired when the skin was prepared. The usual thing is for the tail to taper from base to tip, thus quite unlike the condition found in the Mohave Ground Squirrel.
Measurements.—Nine specimens from the head of Owens Valley, in California, average, in millimeters as follows: total length, 212; tail vertebræ, 50; hind foot, 32.4 (Merriam, 1898, p. 70).
The two immature specimens in the Museum of Vertebrate Zoology, from near Mono Lake, measure as follows, the first figures given being for the male, the second for the female: total length, 195, 185; tail vertebræ, 45, 45; hind foot, 32, 32; ear from crown, 4, 4; greatest length of skull, . . ., 35.6; zygomatic breadth, 21.8, 22.0; interorbital width, 7.4, . . . .
Weights.—Our two specimens weigh, in grams, as follows: male, 83.6; female, 78.0 (in ounces, about 3 and 2¾, respectively).
Type locality.—Queen Station, near head of Owens Valley, Nevada [in Esmeralda County, just across California boundary] (Merriam, 1898, p. 69).
Distribution.—Within the state of California, in only a very limited area comprising the sagebrush valleys of eastern Mono County, namely from southeastern edge of Mono Lake to head of Owens Valley in vicinity of Benton Station (see fig. 18). Life-zone, Upper Sonoran chiefly, barely entering Transition locally (see fig. 23). Southernmost known locality of occurrence, Taylor Ranch, in Owens Valley, two miles south of Benton Station. Altitudinal range, 5,300 to 7,300 feet.
Specimens examined.—A total of 2, both from Mono County: Mono Mills, 1; Dry Creek, 1.
The Soft-haired Ground Squirrels belong to the Great Basin region of the western United States and get into our California list only on the basis of the occurrence of one of the subspecies, the Stephens, in a few places along the eastern border of the state. This is a distinctly different type of ground squirrel from any of our others, notably in the soft, silky "feel" of the hair. In addition, the small size, short slender tail, and uniform light grayish coloration make a combination of characters which is unique among our species.
Unfortunately, our own personal experience with this species has been very limited. In September of 1917 the two of us made especial search for it at the extreme head of Owens Valley. But we were too late in the season; locally well known in the vicinity of Benton, we were assured by the ranchers that the animals had all "holed up" by about the end of July. On the Pellisier Ranch, five miles north of Benton Station, "Picket-pins" were declared to have been present "by the million" from April until July, but it was averred that by the last of August they had all disappeared. Numerous round holes in the ground among the sage bushes were pointed out to us as belonging to these squirrels. There was abundant evidence that coyotes and badgers regularly dig them out. Also we were told that at the season the squirrels are above ground the Indians capture many for food.
On the Taylor ranch this squirrel was reported to be plentiful, but to vary much in numbers from year to year. In the spring of 1916 it was abundant; in 1917 scarcely any were seen.
In the sand-dune area along the east side of Mono Lake, the junior author saw several Soft-haired Ground Squirrels on June 10, 1916. The sand was fairly covered with their tracks. Those individuals seen on June 11 near Dry Creek in the same neighborhood were notably tame. They gave the impression of being flat-bodied, and slid along the ground like lizards, stopping to scrutinize the intruder from the shelter of the first bush reached. One was captured under a bush by being pinned down with the gun.
Mr. Frank Stephens of San Diego, for whom this subspecies was named, states (1906, p. 71) that he found the animals "rather common in the valleys of eastern Mono County." They were feeding on the sagebrush and were exceedingly fat. The date of capture of the type was July 12, 1891 (Merriam, 1898, p. 69).