Family: Sciuridae, Squirrels view all from this family
Description Gray washed with reddish or pinkish above, with broad brown streak down middle of back. Top of head pinkish. Pale gray underneath, with pinkish wash (especially toward front). Relatively long, black-tipped tail, pinkish gray above, reddish to hazel below, edged with pinkish buff. L 9–11 3/4" (230–300 mm); T 1 3/4–3" (44–76 mm); HF 1 1/2–1 7/8" (39–47 mm); Wt 8–12 oz (227–340 g).
Similar Species Most other similar ground squirrels have spotting or mottling on back, and lack reddish coloration on underside of tail. Richardson’s Ground Squirrel’s tail is clay-colored, light brownish, or buff below. Townsend’s Ground Squirrel is smaller, with buff or whitish underparts.
Breeding 1 litter per year of 3–8 young, born late June–early July after gestation of 23–28 days. Size of litter varies with maternal age, with yearlings and 6- to 8-year-olds bearing 3 or 4 young, and 2- to 5-year-olds bearing 6–8 young. Newborns weigh about 1/4 oz (6 g).
Habitat Subalpine meadows, old fields, roadsides, and other grassy areas with short vegetation; in Utah, hay and alfalfa fields.
Range Eastern Oregon, sw Idaho, ne California, n Nevada, and extreme nw Utah.
Discussion The semi-colonial Belding’s Ground Squirrel has one of the longest hibernation periods (seven to eight months) of any North American mammal. By early August, some adult males have entered hibernation. Females follow in late September, and the young, which need more time to accumulate fat, at snowfall. In populations at the summit of Tioga Pass (9,941 feet/3,030 m elevation) in the High Sierras of California, and perhaps in other groups as well, the males apparently hibernate alone, the females often in groups, generally of close relatives. Since food is not stored in the burrow, Belding’s Antelope Squirrel forages voraciously in summer on weed and grain seeds, leaves and stems of green plants, and on grasshoppers, crickets, caterpillars, and other insects. By hibernation it has nearly doubled its body weight. Three-fourths of the stored fat provides energy during hibernation, and the remainder is used after the animals emerge in spring. Males emerge first, tunneling through snow; females ascend one to two weeks later, after snow has melted from the tops of their burrows. Within four to six days females are sexually receptive, but they remain so for only three to six hours. Males, ready for reproduction since their emergence, compete so fiercely for mates—even interrupting copulating rivals—that all are injured, and some are killed. Courtship and mating occur mostly aboveground, which is unusual for ground-living squirrels. On average, females mate four times with three different males, with most offspring sired by more than one male, but most by the first, or first and second, partner. The female digs a nesting burrow that is 1 to 2 feet (about half a meter) below ground and 10 to 15 feet (3–4.5 m) long, with at least two openings, and builds a grass-lined nest inside. Young are born less than a month later, nursed for 26 to 31 days, and appear aboveground in late July or early August. Males disperse after weaning, but females are sedentary, with several generations sharing an ancestral site. Close relatives are highly cooperative, seldom fighting over nest sites. They often share parts of the territory, give alarm calls, and will even chase intruders from one another’s unguarded burrows. Like many of its kind, this species has a single note, a chirp, and a more extended trill. Females give alarm calls more often than males. This squirrel often stands up on its hindlegs to view its surroundings, and exhibits various forms of play behavior. Male Belding’s Ground Squirrels have a life span of three to four years, while females usually live four to six years. The chief cause of death is severe weather: 54 to 93 percent of juveniles and 23 to 68 percent of adults perish during hibernation, and more may freeze or starve during snowstorms after their spring emergence. Among their predators are Coyotes, American Badgers, bears, weasels, and hawks, as well as their own kind. Females that have lost their young to predation sometimes migrate to other sites and kill (but do not eat) the offspring of unrelated females, probably as a means of acquiring safer breeding places; they then settle in that area. Infanticide is also practiced by the relatively carnivorous yearling males, which kill and eat offspring of unrelated females. This ground squirrel is sometimes a garden pest, especially in eastern Oregon and northeastern California, and large colonies may damage pastures and grain fields.
