Home > Education Center > WCSV Species Information > Western Gray Squirrel

Western Gray Squirrel


by Edith Shapiro

Three species of tree squirrels live in the Bay Area: the Eastern Gray Squirrel (Sciurus Carolinensis), the Eastern Fox Squirrel (Sciurus Niger), and the Western Gray Squirrel (Sciurus Griseus). Of these three, only the Western Gray Squirrel is a California native, and its status is of concern to naturalists.

This is a beautiful squirrel, black from nose to tail with a grizzled charcoal gray fur on its back. Its eyes are outlined in a creamy white, which matches its chest. The tail is longer than its body and bushy, with black and white hairs mixed in with the gray. This squirrel is larger than the eastern gray and slightly smaller than the Eastern Fox Squirrel, with weight varying from 700 to 1000 grams (24.5 to 35 ounces).

Western Grays are found on he West Coast of the United States, from north-central Washington to southern California, and in a very small part of western Nevada. They now occupy only a small part of their former range.

The Western Gray was considered one of the most abundant mammals in the northwest in the 1920s, but by the 1930s an epidemic outbreak of mange decimated many populations in Washington. While the eastern gray and the eastern fox squirrels are capable of producing more offspring in times of abundance to compensate for population loss in lean times, the western gray appears unable to do so, thus limiting its ability to rebound from low populations. Additionally, unlike its eastern cousins, which breed twice a year, the Western Gray has one litter a year, with between three and five young per litter.

Western Grays appear to be less tolerant of people and development than their eastern cousins. They are shy squirrels, who are dependent upon older mixed forests with a variety of oak and pine or oak and fir trees with interconnected tree canopies for food, cover, nesting sites, and arboreal travel. These squirrels generally nest in the top third of larger trees, building leaf and twig nests called drays, which they line with lichen, moss and bark shavings. They often build more than one nest, and alternate among them.

Favorite foods are pine nuts, acorns, nuts, berries, fungi, green vegetation and insects. The animals are generally non-territorial, but show a dominance hierarchy at food sites.

Western Grays are a federal Species of Concern, but are not listed as threatened or endangered. Oregon considers them a State Sensitive Species, and Washington state considers them State Threatened. They are still hunted in California and Oregon. Conservation groups in Washington state have petitioned the federal government to provide an emergency listing for this species. Only time will tell whether these efforts will be sufficient to preserve this squirrel.

Wildlife Center of Silicon Valley
3027 Penitencia Creek Road
San Jose, CA 95132
1-408-929-9453 (929-WILD)
info@wcsv.org

Hours: 9 am to 5 pm, 7 days a week
Twitter Facebook Instagram

© 2016 Wildlife Center of Silicon Valley
Privacy Policy
WCSV is a leased facility of the Santa Clara County Parks & Recreation Department,
funded in part by support from the City of San Jose, the City of Milpitas, the City of Sunnyvale and Silicon Valley Animal Control Authority