About Otospermophilus beecheyi (Richardson, 1829)
This species, scientifically named Otospermophilus beecheyi, has mottled upper fur that mixes gray, light brown, and dusky hairs. Its shoulders, neck, and sides are a lighter gray, the fur around its eyes is whitish, and its underside is lighter in color, ranging from buff to grayish yellow. The head and body measure about 30 cm (12 in) long, and the tail adds an additional 15 cm (5.9 in). Adults weigh between 280 and 738 g (9.9 to 26.0 oz). Compared to other ground squirrels, its tail is relatively bushy, so it can easily be mistaken for a fox squirrel at a quick glance.
Like most ground squirrels, California ground squirrels live in self-excavated burrows. Some burrows are used communally, though each individual squirrel has its own entrance. While they quickly become tame in areas frequented by humans and learn to take food left or offered by picnickers, they spend most of their time within 25 m (80 ft) of their burrow, and rarely travel further than 50 m (160 ft) away. In colder parts of their range, they hibernate for several months. Most squirrels remain active year-round in areas with snow-free winters, and may enter estivation for a few days at a time in regions with hot summers.
California ground squirrels are often considered pests in gardens and parks, because they feed on ornamental plants and trees. Their common diet includes seeds like oats, insects such as crickets and grasshoppers, and a variety of fruits. The dental formula for O. beecheyi is 1.0.2.3 1.0.1.3 × 2 = 22.
Their mating season occurs in early spring and typically lasts only a few weeks. Females are promiscuous, so a single litter can have young from multiple different mates. California ground squirrels produce one litter of 5 to 11 young per year, with a gestation period of around one month. Young squirrels open their eyes at about five weeks old and reach sexual maturity around one year old. Juveniles have slightly lighter coloration than adults, and molt at around eight weeks of age, when they leave their natal burrows. This species can live up to six years in the wild.
California ground squirrels use cheek pouches to transport food. They are mostly herbivorous, with seeds, grains, nuts, fruits, and occasionally roots making up most of their diet. In a study published in December 2024, researchers observed California ground squirrels hunting and eating voles.
