Sciurus griseus
western gray squirrel

Sciurus griseus lives on the west coast of the United States. S. griseus can be found in Washington, Oregon, California, and in a very small part of Nevada.

Western grey squirrels are found in woodlands and coniferous forests. They can be found at elevations up to 2500 meters.

The western grey squirrel ranges from about 18 inches to 24 inches in total length with the body and the tail. Their weight varies from 350 to 950 grams.

Sciurus griseus has silver grey fur on its back and a white underside. It has a long bushy tail which is the same silver grey color. Their tail may also have black in it. S. griseus has large ears without tufts.

The western grey squirrel sheds its fur once in the late spring and again in early fall. The fur on the tail is only shed during the spring molting.

Sciurus griseus lives to be between 7 and 8 years old in the wild.

Western grey squirrels live in hollow trees or in nests they build called dreys. These are made of sticks and lined and insulated with softer materials such as moss.

Sciurus griseus is diurnal. While out of the nest S. griseus spends its time grooming, exploring, gathering food, and resting. Grooming can last from 3 to 15 minutes, with most of the time being spent on the head area. Western grey squirrels have a home range size of 0.5 to 7 hectares. Males generally have a larger home range than females. While exploring Sciurus griseus gathers food. Food they don't eat or take back to the nest is buried around their home range. The buried food is called a cache and is later found by their good sense of smell. Caches are usually used in the colder months when food is scarce.

Western grey squirrels do not hibernate but much less time is spent outside during the colder winter months.

Sciurus griseus is non-territorial except when the female is in estrus.

When threatened western grey squirrels make barking sounds while flicking their tails and stamping their feet.

Western grey squirrel's main source of food depends largely upon local habitat characteristics. Those that live in coniferous forests feed primarily on seeds of pinecones. Those that live in hardwood forests feed largely on nuts and acorns. Sciurus griseus is also known to eat berries, fungus, bark, sap, and insects. It opens hard seeds and nuts using its incisors.

Western grey squirrels will feed on the ground as well as in trees.

Some people consider squirrels to be a nuisance.

Sciurus griseus can be hunted and used for food. Western grey squirrels also help disperse and plant trees by burying seeds in their caches which remain uncollected.

Western grey squirrels are a United States species of concern, but are not currently listed as threatened or endangered under the U.S. Endangered Species Act. In late 2002 the Washington subspecies, S. griseus griseus was proposed for listing as an endangered species. In Washington they are considered threatened at the state level, in Oregon they are considered a state sensitive species.