Spermophilus
brunneus
(Idaho Ground Squirrel)
Description:
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 buff 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).
Range:
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 extirpation has occurred in area between
extant populations of northern
and southern subspecies.
Habitat:
Northern populations are associated
with shallow rocky soils in xeric 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.
Diet:
Feeds
on green vegetation and seeds.
Ecology:
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 desiccation (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.
Reproduction:
Not much is known about
its reproduction, but Gestation probably lasts about 25
days. Females produce 2-10 young.
Conservation:
Status: | Unprotected nongame species |
Global Rank: |
|
State Rank: |
S2 |
Important State References:
Yensen, E. 1991. Taxonomy and distribution
of the Idaho ground squirrel, Spermophilus brunneus. J. Mammal. 72:583-600.