Family: Sciuridae (tree squirrels, ground squirrels, chipmunks, flying squirrels, and marmots)
A large ground squirrel, the California Ground Squirrel is about 383-500mm (18 inches) long, including the moderately bushy tail. The tail is longer than half the head and body length, and is almost as bushy as a tree squirrel's tail.
The California Ground Squirrel has a general gray-brown coloration mottled or dappled with lighter flecks on its back. A mantle or darker gray band of color extends from the head down and over the middle of the back. The shoulders and sides of the head are light gray and under parts are light buff. There are rarely any stripes. The large size, dark mantle, and usual lack of stripes distinguish this species from other ground squirrels in California (Jameson and Peeters, 1988).
Range and Habitat
This ground squirrel is found in many plant communities in all the life zones from the coast into the mountains, from southern California to central Washington. There are nine ground squirrels native to California. When the range of two or more species overlap they can be identified by their size, colors, and markings of various patterns of stripes,spots, and mottled appearance. Studies show that when different squirrels live in the same area their eating preferences will vary enough to prevent active competition for the same resources.
The California Ground Squirrels live in open spaces, and are common along roadsides, in fields of stubble or well-grazed pastures (Jameson and Peeters, 1988). They are found in the western half of southern California and northwestern Baja California, generally below about 2200 m (7200 ft.) in elevation.
Behavior: The California Ground Squirrel is diurnal, and strictly ground-dwelling. Some species of ground squirrels become torpid (metabolism slows down) when food is scarce and most use stored fat for energy during estivation (passing the summer or dry season in a torpid state) and hibernation (passing the winter in a resting state).
Reproduction: Ground squirrels usually breed soon after emerging from hibernation. They make their nests in the ground or in rock piles. The California Ground Squirrel has a gestation of a month, usually one litter per year with an average of seven young per litter.
Diet: These common ground squirrels eat a broad range of seeds, berries and leaves of grasses, forbs, and wood plants. They also eat bulbs, tubers, insects and road-killed carrion. They have internal cheek pouches that they use for transporting food to their burrows.
When ground squirrel numbers are high their activities, burrows, and food preferences may cause problems for ranchers and farmers. Predators, which can control squirrel numbers, include coyotes, foxes, wildcats, badgers, large hawks, the golden eagle, and gopher snakes.
Many species of ground squirrels carry fleas which can transmit a bacterium responsible for plague. In wild rodents this plague is referred to as sylvatic plague. When transmitted to humans by the fleas, it causes bubonic plague and pneumonic plague.
Campers should not feed nor play with ground squirrels. Local campgrounds warn when ground squirrels have tested positive for plague. Health officials dust the openings of burrows with flea powder to cut the flea population and therefore possible spread of plague vectors. Prudent behavior and respect suggest that we leave squirrels, and other wild animals, alone. We can learn more about them by observing their wild behavior than by training them to be garbage animals.
Ingles, Lloyd G. Mammals of the Pacific States. 1965. Staford University Press, Stanford, California Jameson, E. W., Jr., and H. J. Peeters. 1988. California Mammals. University of California Press, Berkeley, California.
Lincoln R.J., and G.A. Boxshall. The Cambridge Illustrated Dictionary of Natural History. 1955. Cambridge University Press.
Mellink, Eric, Jaime Luévano, and Jorge Domínguez. 1999. Mamíferos de la Península de Baja California (excluyendo cetáceos). Centro de Investigación Científicay de Educación Superior de Ensenada (CICESE), Baja California, Mexico.
Wilson, Don E., and D. M. Reeder, eds. 1993. Mammal Species of the World. Smithsonian Institution Press, Washington, D.C.
Wilson, Don E., and F. Russell Cole. 2000. Common Names of Mammals of the World. Smithsonian Institution Press, Washington, D.C.