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.