The adaptable, omnivorous, diurnal Eastern Gray Squirrel is the native American mammal people most frequently see east of the Mississippi River. It prefers to den inside trees, but will construct large nests of leaves in the canopy if tree cavities are not available. Learn more about the Sciurus carolinensis, more commonly known as an Eastern Gray Squirrel, in this easy-to-read species overview by the Smithsonian's National Museum of Natural History.