Columbian Ground Squirrel

activity

Activity patterns. A diurnal squirrel that hibernates for eight months or more and is active less than four months per year. Individuals periodically arouse, depending on ambient temperature, and will initiate aboveground activity under favorable conditions. The Columbian Ground Squirrel can be a nuisance near gardens and is considered a pest around cultivated crops and on some rangelands.

Sciuridae

biology_ecology

Habitat. Open grasslands, wet alpine and subalpine mixed forest and forest meadows of the Hudsonian, Canadian, and uppertransition life zones. The Columbian Ground Squirrel is also found on rangelands and agricultural fields.

Sciuridae

biology_ecology

Movements, Home range and Social organization. The Columbian Ground Squirrel lives in dense colonies of 24 - 7 - 61 - 7 ind / ha. Home range averages 4200 m? for males and 1000 m * for females. Male home ranges overlap considerably but defended core areas exist around females during breeding season. Adult females are also territorial, which may help protect juveniles from infanticide until emergence. Females establish territories close to their natal burrows. The Columbian Ground Squirrel is highly social and appears to develop social bonds early in life and these continue throughout their adult life. Cross-fostering experiments indicate that social interactions (recognition of kin and agonistic behavior) are based on experience in the nest and therefore are not directly determined by degree of relatedness, as was previously proposed. Prevalence of infanticide is as high as 7 - 6 % of all juveniles and 12 - 5 % of alllitters but is generally not between close relatives. Dispersal between colonies is much higher in males than in females. This appears to be due to a higher level of adult aggression toward young males and a greater acceptance of daughters by adult females. Dispersal d

Sciuridae

breeding

Breeding. The Columbian Ground Squirrel inhabits burrows with a vegetation-lined nest chamber in which young are born. Males emerge from hibernation in full reproductive condition, and females enter estrus within a few days of emergence 2 - 3 weeks later. Breeding continues for c. 21 days thereafter. However, females that did not successfully breed can re-enter estrus and breed. Yearling females can forego reproduction due to low body mass. Primary factors influencing age at first reproduction appear to be body mass, environmental conditions, and presence of the mother. Lower reproductive performance in older females is due to senescence. Timing of breeding season varies more at higher elevations. Mean littersizes are 2 - 1 - 4 - 2 in the wild and 3 - 4 - 6 in captivity. Litter sizes are negatively correlated with both elevation and latitude. Gestation is 24 days. Young are born hairless and weigh 6 - 8 - 11 - 4 g. Milk composition reflects the need for rapid juvenile growth and is rich in protein and calcium, although low in lipids. Full adult weight is not reached until second year. Young enter hibernation at about 60 % of adult mass.

Sciuridae