The Eastern Fox Squirrel (Sciurus niger) has been introduced to many areas within California. Over time, the fox squirrel has expanded its geographic range and has displaced the native Western Gray Squirrel (Sciurus griseus) in many urban/suburban habitats. Reasons for displacement could be similarities in habitat, space, and/or resource use by each species. A food preferences study was conducted in Claremont, CA at a native California botanic garden. Food items consumed by each species were recorded for one year. Species ate different food items with fox squirrels utilizing more natural foods totaling to 22 items. The gray squirrel utilized 18 food items with 11 of those overlapping with the fox squirrel. The fox squirrel also utilized several plant and tree species whereas the gray squirrel remained with only 3 plant/tree species yet consumed many different reproductive structures such as fruits, catkins, and buds. This study provides information on coexistence of gray and fox squirrels and potential reasons for gray squirrel displacement.
Ortiz, Janel L. and Muchlinski, Alan E.
"Food Selection of Coexisting Western Gray Squirrels and Eastern Fox Squirrels in a Native California Botanic Garden in Claremont, California,"
Bulletin of the Southern California Academy of Sciences:
Available at: http://scholar.oxy.edu/scas/vol114/iss2/4