Family: Sciuridae, Squirrels view all from this family
Description The largest ground squirrel in its range. Mottled above, grayish brown in front, brownish black behind; buff-white or pinkish buff below. Long bushy tail variegated buff and brown with white edges. L 17–21" (430–540 mm); T 6 3/4–9 7/8" (172–252 mm); HF 2 1/8–2 1/2" (53–65 mm); Wt 21–28 oz (600–800 g).
Similar Species Its large size distinguishes this species from most other ground squirrels.
Breeding 2 litters per year of 3–9 young; first litter born April–June, second born August–September. Newborn weighs about 1/4 oz (8 g).
Habitat Nearly always associated with rocky locales such as cliffs, canyon walls, talus slopes, boulder piles, and hills along highways; oak-juniper growth in canyons.
Range Southern Nevada, Utah, Colorado, and panhandle of Oklahoma, south through Arizona, New Mexico, and w Texas.
Discussion The well-named Rock Squirrel is often seen sitting on or running among rocks and makes its den in a burrow beneath them. Active in early morning and late afternoon, it sometimes estivates (becomes dormant) in hot weather. In the north it hibernates, but only for short periods, and is often abroad during winter warm spells. In the southern parts of its range it is active all year. This species climbs bushes and trees nearly as well as tree squirrels to feed on the fruit of juniper or mesquite. It gathers acorns, nuts, and currants, and the seeds of mesquite, cacti, agaves, and many other plants, eating them on the spot or carting them back to the den to be stored. It sometimes damages crops. Rock Squirrels are colonial, organized into maternal aggregations at main den sites, with one dominant male and some subordinate males at peripheral locations. The dominant male defends the colony from other males, but allows females and juveniles to move about freely. Unlike most ground squirrels, males are not in full breeding condition upon emergence from hibernation, but are ready soon thereafter. The young nurse for about two months. They begin foraging for food about three days after emerging from the natal burrow. This species has a sharp, clear, sometimes quavering whistle; its alarm call is short, followed by a lower-pitched trill. Predators include golden eagles, Bobcats, Ringtails, Common Gray Foxes, and rattlesnakes.
