A photo from four years ago. Although called Gray Squirrels, many, like this one, are obviously black in colour. They are the same species, but the melanistic phase. There has been speculation that the reason so many of the gray squirrels in the northerly areas have developed this melanism is that it aids in heat retention, a thermal advantage in fact. Some speculate that the black fur helps with camouflage in woods. Or maybe the reason is something else altogether.