Although Western Gray Squirrels are diurnal, they are secretive by nature and stay away from humans as much as possible. However, they are comparatively frequently hit by automobiles—perhaps because they lack experience of human behavior. The Western Gray Squirrel has a silvery-gray back, a pure-white belly, and a beautiful long, bushy, blackish-gray tail edged with white. These squirrels prefer oak and conifer forests, traveling the arboreal pathways made by interconnecting tree canopies and feeding on pine cones. They also forage on the ground, eating fungi, pine nuts, acorns, bark, and some vegetation. Like Eastern Gray Squirrels, they bury acorns in the fall, presumably finding them later by scent. This behavior is called scatter-hoarding. Western Gray Squirrels usually produce only one litter per year. The female builds a nest of sticks for raising her young, and the squirrels often sleep in nests in tree cavities. They are not territorial about their nests. Only one squirrel occupies a nest at a time, except for a mother with her young, but several squirrels may nap in the same cavity in the course of a day.

Links:
Mammal Species of the World
Click here for The American Society of Mammalogists species account