The black squirrel occurs as a "melanistic" subgroup of both the eastern gray squirrel and the fox squirrel. Their habitat extends throughout the Midwestern United States, in some areas of the Northeastern United States, eastern Canada, and also in the United Kingdom. The overall population of black squirrels is small when compared to that of the gray squirrel. The black fur color can occur naturally as a mutation in populations of gray squirrels, but it is rare. The rarity of the black squirrel has caused many people to admire them, and the black squirrels enjoy great affection in some places as mascots. In several U.S. states, as well as in Canada and the United Kingdom, black squirrels have been introduced into the wild in the hope of increasing their numbers.