The California ground squirrel, or Otospermophilus beecheyi, is a common mammal found across the western United States, particularly in California and Oregon. These adaptable squirrels are a frequent sight in diverse settings, from rural grasslands and open woodlands to suburban yards and agricultural fields, thriving alongside human development.
Physical Description and Habitat
The California ground squirrel’s fur is a mottled mix of brownish-gray and white, with a lighter gray patch around its neck and shoulders. An adult’s body length ranges from 9 to 11 inches, with a semi-bushy tail that adds another 5 to 9 inches. These squirrels weigh between 280 and 738 grams, have a whitish ring of fur circling their eyes, and prominent ears for a ground squirrel.
These animals prefer open areas like grasslands, pastures, and oak savannas, avoiding dense forests. They are semifossorial and live in extensive burrow systems they excavate. These burrows are used for nesting, raising young, storing food, and as a refuge from predators and extreme temperatures. A colony can consist of a few individuals to over 20, with each squirrel typically having its own entrance. The squirrels rarely venture more than 50 meters from their burrow.
Behavior and Diet
California ground squirrels are diurnal, meaning they are active during the day. They spend their time foraging, sunbathing, or standing alert on their hind legs to watch for danger. This sentinel behavior is a social defense, and they use a series of sharp chirps and whistles to warn other colony members of threats. While social, males can be territorial during the spring mating season.
Primarily herbivores, their diet shifts with the seasons. In the wet winter and spring, they feed on green grasses and leaves, switching to seeds, grains, nuts, and fruits as vegetation dries. They also eat insects like crickets and grasshoppers. They use large cheek pouches to transport food back to their burrows for immediate consumption or storage. In regions with hot, dry summers, adults may enter a state of dormancy called estivation to conserve energy.
Predators and Survival Strategies
A variety of predators hunt California ground squirrels, including rattlesnakes, coyotes, badgers, eagles, and foxes. One defense against rattlesnakes involves chewing shed rattlesnake skins and then licking their fur to apply the snake’s scent. This olfactory camouflage masks their own scent, making it harder for hunting rattlesnakes, which rely on smell, to detect them in their burrows. This scent application is seen more often in adult females and juveniles, who are more vulnerable to snake predation.
Interactions with Humans
The adaptability of California ground squirrels often brings them into conflict with people. They are considered agricultural pests, causing millions of dollars in damage annually by consuming crops like nuts, fruits, and grains. Their burrowing can also cause structural problems for farm equipment, building foundations, and irrigation systems.
Squirrels can also pose a health risk as reservoirs for diseases transmissible to humans, most notably bubonic plague. While the disease is serious, transmission to humans is rare. It occurs through the bite of an infected flea that has fed on a squirrel, not from the squirrel directly.