Behaviors of the native Western Gray Squirrel (Sciurus griseus) and the invasive Eastern Fox Squirrel (Sciurus niger) in Los Angeles and surrounding counties

The Eastern Fox Squirrel (<italic>Sciurus niger</italic>) 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 (<italic>Sciurus griseus</italic>) in many urban/suburban habitats. Reasons for displacement could be similarities in habitat, space, and/or resource use by each species. My study encompasses four behaviors including: daily activity, reproduction, food preferences, and predator-risk. Daily activity observations and predator-risk experiments showed overlap in temporal and spatial niche of both species. Differences between species lie in food preferences with fox squirrels utilizing a wider variety of natural foods and novel food items. Gray squirrels appear to remain stable in reproductive activity at a projected shorter-term coexistence site but a variety of factors may be leading to declines in the following years. This study provides information on coexistence of gray and fox squirrels and potential reasons for gray squirrel displacement