Eastern Fox Squirrel

The eastern fox squirrel 

is found in the eastern and central U.S. (other than New England, most of New Jersey, western New York and northern and eastern Pennsylvania), west to the Dakotas, Colorado and Texas, in the southern prairie provinces of Canada, and they have been introduced to California. 

In the northeast, they are generally gray above with yellowish undersides. In the western part of their range, they are gray above and rust colored on the undersides. 

In the southern part of their range, they are black with a white stripe on their faces and a white top on their tails. I have seen them twice. The first time near downtown Denver 

and the second time on the campus of the University of California in Berkeley.