The largest of the tree squirrels in North America they normally have grayish fur with silver highlights. The ears, feet and tail have more reddish coloration. The one pictured is a beautiful natural black, however it is the same species as the dominant color.
They are found across the US, frequenting trees and running on the ground in remote areas to walking power lines in the cities. They have adapted to live almost everywhere.
In our neighborhood in Omaha we regularly see some with black coat. This day it was showing off a special sheen in the spring sun.