Idaho Ground Squirrel

activity

Activity patterns. Idaho Ground Squirrels are diurnal. They are active aboveground from late January to early August, usually less than c. 4 months for an individual. Males emerge slightly earlier than females and enter hibernacula a bit earlier in summer.

Sciuridae

biology_ecology

Habitat. Open meadows of mixed forbs and grasses. The Idaho Ground Squirrel extends into open park-like forests but quickly disappears from open conifer stands when fire suppression and timber harvest increases canopy cover and woody encroachment that result in tall dense exotic or barren herbaceous understory. Subspecies endemicus occurs at lower elevations than brunneus (less than 1000 m). Low burrow densities are associated with exotic and annual plant cover; high burrow densities are associated with native and perennial plant cover.

Sciuridae

biology_ecology

Movements, Home range and Social organization. Distribution of the Idaho Ground Squirrel is fragmented, with northern subpopulations of brunneus at very low densities. In the late 1980 s, populations of brunneus declined dramatically to ten animals in one isolated population. Range-wide population declined from 40,000 individuals in 1984 to 4000 in 2000, with local extirpation of some populations. Individuals live in low-density colonies but appear to be relatively solitary within local aggregations. One simple shrill alarm call is used when threatened.

Sciuridae

breeding

Breeding. Idaho Ground Squirrels inhabits burrows with a vegetation-lined nest chamber in which young are born, but they also use shallow escape burrows or more substantial hibernacula. Males emerge c. 2 weeks before females and court, guard, and copulate within 1 - 2 days of female emergence. Mating usually occurs belowground. Guarding of females continues if density of receptive females is low; otherwise, males might seek other females over a breeding season that lasts 12 - 13 days. Duration and order of mating are important; last male to guard the female fathers more than 65 % of young. Copulatory plugs are produced perhapsto preserve this last male-mating advantage. Large males dominate small males. Single litters averaging 5 - 2 young emerge from late March to early April in subspecies endemicus or 5 - 6 weeks later in brunneus.

Sciuridae