Spermophilus beecheyi is found throughout most of California, most of Western Oregon and portions of Western Nevada. This species also occurs in portions of southwestern Washington, and Baja California. (MacClintock, 1970; Whitaker, Jr., 1980)
Spermophilus beecheyi has successfully exploited many habitat types. California ground squirrels are terrestrial, and semifossorial, requiring habitats with some loose soil where they can excavate an appropriate burrow.
You may find them colonizing fields, pastures, grasslands and in open areas such as oak woodlands. The only habitat they do not use is deserts. You may find them down in valleys and up on rocky outcrops in the mountains, to an elevation of 2,200 m. They can be found in urban, suburban and agricultural areas. By and large this species is widely distributed within its range. (Evans and Holdenried, 1943; MacClintock, 1970; Whitaker, Jr., 1980)
California ground squirrels have mottled fur, with gray, light and dark brown, and white present in their pelage. They typically have a darker mantle. The shoulders, neck and sides of this species are a lighter gray. The bushy tail is a combination of the colors that appear on the back. The underside is a lighter combination of light brown, gray and white. California ground squirrels have a white ring around each eye.
The body length can range from 330 to 508 mm and tail length from 127-229 mm. These animals range in weight from 280 to 738 g. The ears are > 10 mm and < 25.4 mm. The dental formula is 1/1 : 0/0 : 2/1 : 3/3 = 22. (Alden, et al., 1998; Ingles, 1947; Linsdale, 1946; MacClintock, 1970; Whitaker, Jr., 1980)
Females of this species are considered promiscuous. They will often mate with more than one male, either through force or selectivity, and therefore the offspring of a single litter may have multiple paternity. Males may also mate with several females. (Boellstorff, et al., 1994)
The mating season of S. beecheyi occurs in early spring, typically for a few weeks only. As with most ground-dwelling squirrels, breeding occurs just after the animals emerge from their winter burrows. This is highly dependent on the area and climate the squirrel inhabits, since the timing of hibernation varies geographically, with elevation, and with other ecological factors.
Males possess abdominal testes which drop into a temporary scrotum during the breeding season only.
Females produce one litter per year after of a gestation period of roughly one month. Litters range in size from five to eleven young. The sex ratio of young are about 1:1.
Young S. beecheyi may open their eyes at around 5 weeks of age. They first leave burrows at 5 to 8 weeks of age, and are wenaed between 6 and 8 weeks. The coloring of the young is somewhat lighter than that of adults. Molting for young begins a few weeks after they emerge from their burrows. Young may begin to burrow at 8 weeks of age. They reach sexual maturity no sooner than 1 year old. In the first year of life, some ground squirrels remain above ground and do not hibernate. (Cato, 2003; Evans and Holdenried, 1943; Whitaker, Jr., 1980)
The only active parenting is provided by the mother. Females give birth to their pups in a burrow, and will move young into new burrows frequently to avoid predation. Young are helpless at birth, and their eyes do not open until they are about 5 weeks old. Shortly after their eyes open, the young pups leave the burrow and begin to explore their surroundings. (Alden, et al., 1998; Boellstorff, et al., 1994; Evans and Holdenried, 1943; Whitaker, Jr., 1980)
The lifespan of a California ground squirrel can be up to 6 years in the wild. They have lived as long as 10 years in captivity. (MacClintock, 1970)
California ground squirrels live in burrow systems that can house many generations, forming a sort of colony. Each individual has an entrance of their own. They tend to stay within 150 yards of their burrow system and retreat, usually only to their entrance of that burrow system. They frequently spend time sunning themselves. Depending on the climate, they may hibernate, or aestivate to escape undesirable temperatures. Males are more aggressive than females and sometimes appear territorial. (Alden, et al., 1998; Evans and Holdenried, 1943; Linsdale, 1946; MacClintock, 1970; Whitaker, Jr., 1980)
California ground squirrels use a variety of sounds, tail signals and scent production as means of communication. For example, glandular folds anterior to the tail region are used for individual identification. When finding a mate or mates, females may approach or males may approach, but scent cues are important in identifying reproductive condition. (Evans and Holdenried, 1943; Linsdale, 1946)
California ground squirrels use cheek pouches while they are foraging to collect more food than would otherwise be possible in one sitting. They are also known to cache or store food. They exploit a variety of food sources, which probably contributes to their success as a species.
The diet of these animals, as their genus name would suggest, is primarily seed-based. California ground squirrels consume seeds, barley, oats, and acorns (Quercus): valley oak, blue oak, coast oak). They also eat fruits, like gooseberries and pears, and quail (Callipepla) eggs. They include insects in their diets when they are available, and have been known to eat grasshoppers, crickets, beetles and caterpillars. They also eat roots, bulbs, and fungi, such as mushrooms. (Linsdale, 1946; MacClintock, 1970; Whitaker, Jr., 1980)
These ground squirrels are highly vulnerable to predation due to their diurnal habits, open habitat, and the concentrations of conspecifics found in any particular colony. They are known to be preyed upon by red-tailed hawks, golden eagles, coyotes, foxes, badgers, weasels, house cats, dogs, and wild cats such as bobcats and pumas. In addition, large snakes may prey upon them.
Spermophilus beecheyi individuals probably avoid predation mainly through the use of burrow systems and vigilance. They are also cryptically colored. Also, they have skin glands on their back, just posterior to the shoulders, which secrete an odorous oil which could deter predators. (Alden, et al., 1998; Linsdale, 1946)
Due to their diet, California ground squirrels could play a role in regulating some insect populations. They may aid in seed dispersal when a cache is forgotten. they help to aerate the soil through their excavation of burrows, and create habitat for many other animals, such as other rodents and snakes, which occupy empty burrows. (Linsdale, 1946)
This species may threaten agricultural crops, such as grain fields and orchards, through their foraging activities. They are potential carriers of diseases, such as tularemia, bubonic plague, and sylvatic plague. The two latter diseases are from fleas the squirrels carry. (Alden, et al., 1998; Boellstorff, et al., 1994; MacClintock, 1970)
There are no special conservation practices currently for S. beecheyi. Some control of their numbers has been attempted, costing several hundred thousand dollars. These are generally targeted responses to crop damage or disease outbreaks. (Boellstorff, et al., 1994; MacClintock, 1970)
Spermophilus beecheyi was named for Frederick William Beechey, who spent time exploring Northern California from 1826-1828. This species used to be known as Otospermophilus beecheyi.
Marcie Lima (author), Humboldt State University, Brian Arbogast (editor), Humboldt State University.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
either directly causes, or indirectly transmits, a disease to a domestic animal
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
digs and breaks up soil so air and water can get in
places a food item in a special place to be eaten later. Also called "hoarding"
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
living in cities and large towns, landscapes dominated by human structures and activity.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Alden, P., F. Heath, R. Keen, A. Leventer, W. Zomlefer. 1998. National Audubon society field guide to California. New York: Alfred A. Knopf.
Boellstorff, D., D. Owings, M. Penedo, M. Hersek. 1994. Reproductive behaviour and multiple paternity of California ground squirrels. Animal Behaviour, 47(5): 1057-1064.
Cato, F. 2003. "San Diego Natural history Museum Field Guide: Spermophilus beecheyi " (On-line). Accessed June 17, 2003 at http://www.sdnhm.org/fieldguide/mammals/sper-bee.html.
Evans, F., R. Holdenried. 1943. A population study of the Beechey ground squirrel in Central California. Journal of Mammalogy, 24(2): 231-260.
Ingles, L. 1947. Mammals of the Pacific States. Stanford, California: Stanford University Press.
Linsdale, J. 1946. The California ground squirrel. Berkeley and Los Angeles: University of California press.
MacClintock, D. 1970. Squirrels of North America. New York and Toronto: Van Nostrand Reinhold Company.
Whitaker, Jr., J. 1980. National Audubon society field guide to North American mammals. New York: Alfred A. Knopf.