California ground squirrels are common and easily observed ground squirrels of the western United States and the Baja California Peninsula. Their fur contains a mixture of gray, light brown and dusky hairs; the underside is lighter, buff or grayish yellow. The fur around their eyes is whitish, while that around the ears is black. The tail is quite bushy for a ground squirrel, and at a quick glance these squirrels can be mistaken with Fox squirrels.
California ground squirrels are found in the western United States and the Baja California Peninsula (northwestern Mexico). They are common in Oregon and California and their range has recently extended into Washington and northwestern Nevada. California ground squirrels inhabit farmlands, fields, chaparral, pastures, and grasslands. They can also live in urban and suburban areas.
California ground squirrels are social creatures that live in burrows which they excavate themselves. Some burrows are occupied communally but each individual squirrel has its own entrance. Although they readily become tame in areas used by humans, and quickly learn to take food left or offered by picnickers, they spend most of their time within 25 m (82 ft) of their burrow and rarely go further than 50 m (160 ft) from it. California ground squirrels are diurnal being active during the day. They like to spend time sunning on warm days. During foraging, they use cheek pouches to collect more food than they could eat in one sitting and store food to consume it later. In the colder parts of their range, California ground squirrels hibernate for several months, but in areas where winters have no snow, most squirrels are active year-round. In those parts where the summers are hot, they may also estivate for periods of a few days. These squirrels use different sounds, tail signals and scent production in order to communicate with one another.
California ground squirrels have a polygynandrous (promiscuous) mating system. This means that both males and females in this species have multiple mates during the breeding time. Mating season takes place in early spring and lasts only for a few weeks. Females give birth to one litter per year consisting of 5 to 11 babies. The gestation period lasts around one month. The young are born helpless and open their eyes at about 5 weeks of age. In order to avoid predation mothers often move their young to new burrows. Pups start to emerge from burrows at around 8 weeks of age, and become weaned between 6-8 weeks. The coloration of the young is slightly lighter than the adults and they start to molt at about 8 weeks of age. California ground squirrels reach reproductive maturity after one year old.
There are no major threats to California ground squirrels at present.
According to IUCN, the California ground squirrel is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.
California ground squirrels play an important role in the ecosystem they live. They act as seed dispersals when hiding their food and then forget about it. These squirrels help soil aeration due to their habit of digging burrows and also create habitat for other rodents and snakes, which use them as shelters.