They mate over an extended period ranging from December through June. Western gray squirrels reach sexual maturity at 10 to 11 months, and at approximately one year of age, will begin breeding.

Western gray squirrels eat berries, nuts, a variety of seeds, and the eggs of small birds. Nesting mothers will use their tail hair to line birthing nests. Tail hair is replaced only in the spring. Tree squirrels undergo a complete head-to-tail molt in the spring and a rump-to-head molt in the fall. Also, it stays in a curved upwards in an 'S' shape. The tail is long and typically very bushy.

The ears turn reddish-brown at the back in the winter. The dorsal fur is a silver gunmetal gray, with pure white on the underside there may be black flecks in the tail. Western gray squirrels exhibit a form of coloration known as counter shading. It is the largest native tree squirrel in the western coastal United States. 35 to 1 kilogram (0.77 to 2.20 lb), and length (including tail) from 43 to 61 centimetres (17 to 24 in). niger (which have been introduced into its native range), these squirrels are shy, and will generally run up a tree and give a hoarse chirping call when disturbed. Compared with the eastern gray squirrel S. It has plantigrade, pentadactyl feet with two phalanges. Sciurus griseus is the largest tree squirrel in the Sierra Nevada and Central California range. The western gray squirrel was first described by George Ord in 1818 based on notes taken by Lewis and Clark at The Dalles in Wasco County, Oregon. In some landscapes, the western grey squirrel has lost habitat or experienced local extinction due to competition with other squirrel species and other pressures on their population. anthonyi (which ranges from San Luis Obispo to northern Baja California). nigripes (from south of San Francisco Bay to San Luis Obispo County, California) and S. There are three geographical subspecies: Sciurus griseus griseus (central Washington to the western Sierra Nevada in central California) S.

In some places, this species has also been known as the silver-gray squirrel, the California gray squirrel, the Oregon gray squirrel, the Columbian gray squirrel and the banner-tail. The western gray squirrel ( Sciurus griseus) is a tree squirrel found along the western coast of the United States and Mexico.

Grey squirrel hibernation