Page:Natural History of the Ground Squirrels of California.djvu/104

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Other names.—San Bernardino Ground Squirrel; San Bernardino Spermophile; Yellow-headed Chipmunk, part; Spermophilus bernardinus; Spermophilus chrysodeirus brevicaudus; Citellus chrysodeirus bernardinus; Callospermophilus bernardinus; Tamias chrysodeirus brevicaudus; Tamias lateralis, part.

Field characters.—The same as for the Sierra Golden-mantled Ground Squirrel. The slight shortness of tail characterizing this race is certainly not a sufficient difference for notice at any distance.

Description.—In all pelages: Coloration, as far as we can see after comparing large series of specimens, exactly as in the Sierra Golden-mantled Ground Squirrel. None of the paleness is apparent such as characterizes the Inyo race.

Variations.—Of the same sort as discussed under the Sierran race.

Measurements.—Average and extreme measurements, in millimeters, of twenty full-grown specimens from the San Bernardino Mountains are as follows: Ten males total length, 260 (240–278); tail vertebræ, 80 (68–90); hind foot, 40 (36–43) greatest length of skull, 43.5 (42.0–45.6); zygomatic breadth, 26.6 (25.5–27.6) interorbital width, 10.7 (10.1–11.3). Ten females: total length, 251 (236–271) tail vertebræ, 78 (72–86); hind foot, 38.5 (35–42); greatest length of skull, 41.8 (40.4–43.0); zygomatic breadth, 25.5 (24.2–26.8); interorbital width, 10.2 (9.7–10.8).

Unfortunately, ear measurements from fresh specimens are not available; but dried skins look to have decidedly smaller ears than in either the Sierra or Inyo race, this character being especially noticeable in the young. It will be noted from the above measurements in comparison with those given for chrysodeirus and perpallidus, that the body size of bernardinus is just the same as in the others, while the tail length is decidedly less. This, then, is the character of the subspecies bernardinus, shortness of tail; and it shows up well in a series of specimens, even very young ones. However, this difference in tail length between adults of bernardinus and of chrysodeirus averages but somewhat less than half an inch, and individual variation brings overlapping in a certain proportion of specimens. In other words, an extra short-tailed chrysodeirus might even have a longer tail than an extra long tailed bernardinus. The race bernardinus is but slightly and incompletely differentiated.

No weights are available for this subspecies.

Type locality.—San Bernardino Peak, San Bernardino Mountains, San Bernardino County, California (Merriam, 1893, p. 134).

Distribution.—Restricted to the relatively small area, not more than twenty-five miles in greatest width, comprised in the higher parts of the San Bernardino Mountains (see fig. 24). Belongs to the Boreal zone and upper part of the Transition. Extends up to the very summit of San Gorgonio Peak, 11,485 feet altitude, and down locally, as near Bear Lake, to 6,700 feet (Grinnell, 1908, p. 141).

Specimens examined.—A total of 84, from the following localities, all in San Bernardino County, California: San Gorgonio Peak, 2; Dry Lake, 3; South Fork of Santa Ana River, 14; Sugarloaf Mountain, 2; Bluff Lake, 61; Bear Valley, 2.

Far separated by desert and lowland from the habitat of its near relative on the Sierras, the Golden-mantled Ground Squirrel of the San Bernardino Mountains has developed slight peculiarities which make it recognizable as a distinct race. It has the most restricted range, probably, of any species or subspecies of ground squirrel in the state. It seems strange that it should be wholly lacking as an inhabitant of the San Gabriel and San Jacinto mountains, so near by on either hand and seemingly of quite similar environment to the San Bernardinos. On the higher parts of the San Bernardino Mountains it is certainly not on the wane, but thrives greatly, perhaps outnumbering all the other members of the squirrel family put together.