Columbian ground squirrel

Spermophilus columbianus

TAXONOMY

Arctomys columbianus (Ord, 1815), between the forks of the Clearwater and Kooskooskie Rivers, Idaho County, Idaho, United States. Four subspecies.

OTHER COMMON NAMES

French: Spermophile du Columbia; German: Columbia Ziesel. PHYSICAL CHARACTERISTICS

12.8-16.1 in (32.5-41.0 cm), males: 14.3-24.7 oz (405-699 g); females: 12.2-18.7 oz (347-529 g). Nose and face are tawny and body is grayish to tawny, belly and feet are cinnamon.

DISTRIBUTION

Rocky Mountains of eastern British Columbia and western Alberta. South along the Rocky Mountains into western Montana and central Idaho. Lives as far west as south central British Columbia, eastern Washington, and northeastern Oregon.

HABITAT

Subalpine to alpine meadows with sandy to coarse substrates for burrowing. Prefers to hibernate in areas where snow accumulates, such as in shallow depressions, or under shrubs.

BEHAVIOR

Lives in clusters of related females that overlap in range with an adult male. Male home ranges overlap some but during the breeding season they defend a core territory that includes several reproductively mature females. Females will defend the natal burrow of pre-weaned young from all other squirrels, including the adult male. Dispersal is male-biased and occurs after a squirrel's first hibernation. Hibernation is from August-October to April. Adults are active above ground for approximately 100 days.

FEEDING ECOLOGY AND DIET

Polygymous. Consume a variety of forbs and grasses with preference for forbs. Will consume invertebrates and carrion. Males will cache seeds in the fall for consumption in early spring.

REPRODUCTIVE BIOLOGY

Breeding commences a few days after females emerge from hibernation. Gestation is 24 days and lactation lasts for about 30 days. A single litter per year averages 2.3-4.6 pups with a maximum of 7. Only about 15% of yearling females breed on average but more can breed if spring conditions are good.

CONSERVATION STATUS

Not threatened.

SIGNIFICANCE TO HUMANS

Considered an agricultural pest that competes with livestock for food. Intermediate host for the Rocky Mountain wood tick (Dermacentor andersoni), which can carry Rocky Mountain spotted fever in the United States. Can also carry the bubonic plague Yersinia pestis, which can be transmitted to humans through flea bites. ♦

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