California Ground Squirrel

activity

Activity patterns. The California Ground Squirrel is diurnal and hibernates for c. 6 months, depending on elevation, in relatively simple burrow systems. It is active aboveground beginning in spring, usually late March for males and 2 - 4 weeks later for females. Immergence begins in September for males and October for females; young remain aboveground sometimes until November.

Sciuridae

biology_ecology

Habitat. [. ow-elevation grasslands and chaparral to meadows and open forest woodlands from sea level to more than 3000 m. The California Ground Squirrel can thrive in human-disturbed habitats such as roadsides, parks, modest-density human housing, successional forests, and agricultural lands of nearly all types. Following forestfires, densities of California Ground Squirrels increase in an apparent positive response to ground cover reduction.

Sciuridae

biology_ecology

Movements, Home range and Social organization. The California Ground Squirrel lives in loosely structured colonies and is abundant throughout their distribution. Densities are 8 - 92 ind / ha. Individuals do not appearto be territorial, and home ranges overlap considerably. Females (means 616 - 902 m ®) typically maintain larger home ranges than males (means 270 - 375 m?), and home ranges do not change appreciably in size during and after the breeding season. California Ground Squirrels have evolved a fascinating suite of behavioral and physiological adaptations to defend against snakes, including venomous rattlesnakes. These behaviors are noted early in life and continue to be developed such that young individuals completely avoid snakes and adults actively seek, harass, and warn of snakes. They create distraction displays by tail flicking and increase amount of blood flow to the tail only for rattlesnakes, which hunt primarily by infrared thermal detection. Individuals are able to assess predation risk by tone and pace of rattling and deliberately provoke snakes to garner information. They induce rattling by kicking sand to assess specific risk factors such as probability of a st

Sciuridae

breeding

Breeding. The California Ground Squirrel inhabits burrows with a nest chamber in which young are born. Males typically emerge before females in spring. Individuals mate soon after female emergence. Males and females appear capable of mating multiple times during a breeding season in a promiscuous mating system. Gestation lasts 25 - 30 days, and litters have 3 - 11 young, varying with elevation and latitude. Infanticide is common in the California Ground Squirrel and, where systematically studied, appears to be performed almost exclusively by neighboring mothers, who frequently cannibalize victims. Young disperse from natal areas and are able to reproduce in their first year.

Sciuridae