Measurements.—Ten adults from Mabton and North Yakima, Yakima County, average: total length 212.2; length of tail 45.7; hind foot 33.9.
Distribution.—The Upper Sonoran Life-zone area of the Yakima Valley from Ellensburg ([Howell], 1938: 63) south to the Columbia at Kennewick (W. W. D.).
Remarks.—This race is probably derived from C. t. mollis of Oregon, from which it is but slightly differentiated. It was known for many years as Citellus mollis yakimensis. For use of the name townsendii see [Howell] (1938: 62).
The head and body are about 6-1/2 inches long and the tail is about 2 inches in length. The head is large with low, rounded ears and large eyes. The neck is distinctly constricted and the body is plump. Adults are "pot-bellied." The legs are short and the feet small. The tail is short, round at the base but bushy throughout the rest of its length. The pelage is short and rather harsh. In color the upper parts are yellowish gray flecked with tiny, pale dots. The underparts are buffy. The face, thighs and tail are reddish buff.
Ground squirrels occur in parts of Europe, Asia, and much of western North America. [Howell] (1938: 36-37) recognizes eight subgenera and thirty-one species in North America. Three subgenera occur in Washington, namely: Citellus, the spotted ground squirrels, represented by Citellus townsendii, Citellus washingtoni and Citellus columbianus; Otospermophilus, the long-tailed ground squirrels, represented by Citellus beecheyi; and Callospermophilus, the striped ground squirrels, represented by Citellus lateralis and Citellus saturatus.
All ground squirrels are diurnal and consequently are familiar to man. Most species bear local names and the striped or mantled ground squirrels are often mistaken for chipmunks. Some species are destructive to crops, especially grain. In addition they harbor sylvatic plague. Economically the genus Citellus is of great importance in Washington.
All Washington ground squirrels live in burrows which they construct themselves. The life histories of the two striped species are less well known than those of the more economically important species. All species hibernate. The striped species disappear in October and reappear the following March. This can be called true hibernation. The long-tailed ground squirrels probably hibernate at high altitudes but aestivate in more arid localities. In Washington the Douglas ground squirrel occupies an area that is relatively temperate and humid. They may hibernate or aestivate, depending on local conditions, or they may remain active all year. The spotted ground squirrels disappear in midsummer and sleep (aestivate) until the following spring, for in their arid habitat the disappearance of green food in late summer and fall makes living conditions almost as unfavorable as in winter.
Townsend ground squirrels range from central Washington south to southern Nevada and from the Cascade Mountains east to eastern Idaho and central Utah. Five races are recognized, only one of which occurs in Washington, where it is confined to the Upper Sonoran Life-zone. It occupies the sagebrush area, being most common where the sage is in scattered clumps separated by grassy areas. Occasionally these squirrels occupy extensive grasslands where sage is scarce and in the Yakima area may enter pastures and fields. They live in colonies, often with more than ten separate burrows to the acre.
Burrows are dug in dusty ground, either near sage bushes or in openings among them. Well-worn trails lead from feeding places to openings of burrows. Mouths of burrows are usually situated on flat ground and are surrounded by a rim of excavated earth four to six inches high. If located on a slope, the excavated earth collects as a mound on the lower side, and serves as a look-out post for the squirrels. Burrows excavated by [Scheffer] are described by [Howell] (1938: 5). One reached a depth of 5-1/4 feet at a point where it branched 11 feet from the entrance. One branch led to the nest chamber three feet to the right of the main tunnel. The other reached a depth of six feet at a point 14 feet from the entrance, then turned upwards at a 70 degree angle and reached the surface through a partly obstructed entrance, 12 feet from the original entrance. The nest chamber was 6-1/2 inches in diameter and filled with a perfectly dry nest of fine grass, partly broken and shredded.