Black squirrels are a melanistic subgroup of squirrels with black colouration on their fur. The phenomenon occurs with several species of squirrels, although it is most frequent with the eastern grey squirrel (Sciurus carolinensis) and the fox squirrel (Sciurus niger). Black morphs of the eastern grey and fox squirrels are the result of a variant pigment gene. Several theories have surfaced as to why the black morph occurs, with some suggesting that the black morph is a selective advantage for squirrels inhabiting the northern ranges of the species, with the black fur providing a thermal advantage over its non-melanistic counterpart.
Black squirrels share the same natural range as their non-melanistic counterparts. In addition to their natural range, black morphs of eastern grey squirrels were also introduced into other areas of Canada, the United Kingdom, and the United States during the 19th and 20th centuries. Black morphs of eastern gray squirrels occur most frequently in the northern portion of its range around the Great Lakes Basin. Conversely, black morphs of fox squirrels typically occur most frequently in the southeastern portions of the species' natural range, the southeastern United States. Although they are found more frequently in those regions, the colouration remains uncommon in most areas that these species inhabit. However, black morphs of eastern grey squirrels form the majority of the species' population in the Canadian province of Ontario, and the U.S. state of Michigan.
Several municipalities and post-secondary schools in the United States have adopted a black squirrel for branding purposes, using it as a symbol and/or mascot. Some municipalities that have adopted the black squirrels as a symbol for their community have also passed ordinances that discourage attempts to threaten them.
