Spermophilus brunneus
(Idaho Ground Squirrel)

Order: Rodentia
Order Description:Rodents
Family: Sciuridae
Family Description: Chipmunks, Marmots and Squirrels

The Idaho ground squirrel resembles the Columbian ground squirrel, but is much smaller. It is vaguely spotted and grayish brown above, with its lower back mostly brown; underneath is is grayish to yellowish. Its shoulders and forelegs are a buffClick word for definition color, while its outer hindlegs and underside of the tail are rust brown. The tail has 5 to 8 alternating light and dark bands. It has a white chin and a rust-brown nose. Total length is 8 ¼ to 8 ¾ inches (211-220 mm), and its tail length is 1 ¾ to 2 inches (46-50 mm).

Endemic to 5-county area of west-central Idaho. Northern subspecies (brunneus) is presently known only from about 2 dozen isolated demes in Valley and Adams counties; these demes occur at mid-elevations (1150-1550 m). Southern subspecies (endemicus) occurs at lower elevations (670-975 m) north of Payette River in Gem, Payette, and Washington counties. Apparent extirpationClick word for definition has occurred in area between extantClick word for definition populations of northern and southern subspecies.

Northern populations are associated with shallow rocky soils in xericClick word for definition meadows surrounded by ponderosa pine and Douglas-fir forests; southern populations inhabit low rolling hills and valleys now dominated by annual grassland with relict big sagebrush and bunch grasses. Species may occur on slopes and (rarely) ridges.

Feeds on green vegetation and seeds.

Relatively little was known about this species until quite recently, and much is yet to be learned about it. The southern populations emerge in late January to early February and cease above-ground activity in late June-early July; the northern populations are active above ground from late March-early April until late July-early August. Activity is restricted by time of the spring snow melt and vegetation desiccationClick word for definition (drying) in mid to late summer. Individuals dig burrows; entrances are often under rocks and logs. Burrows are extensive in shallow, rocky soils, but nest burrows are located in adjacent areas with deeper (greater than 1 m), well-drained soils. Indiscriminate shooting and poisoning are continued threats to the species and because of its small population and restricted range, the long-term future of its populations may be precarious.

Not much is known about its reproduction, but GestationClick word for definition probably lasts about 25 days. Females produce 2-10 young.

Status: Unprotected nongame species

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Important State References:
Yensen, E. 1991. Taxonomy and distribution of the Idaho ground squirrel, Spermophilus brunneus. J. Mammal. 72:583-600.

Information written by Donald Streubel,© 2000
Map image provided by
Stephen Burton,© 2000
Design by Ean Harker©1999, 2000.