The black squirrel, a natural variant of the grey squirrel, owes its dark appearance to a genetic alteration, which results in greater production of the pigment eumelanin. This mutation, also recorded in the fox squirrel (Sciurus niger), is thought to have entered the grey squirrel population through occasional interbreeding. Although the black squirrel differs markedly in appearance, studies have found no significant variation in behaviour, diet, or temperament when compared to the grey squirrel. Both are found in similar habitats, including woodlands, parks, and urban areas, and show comparable adaptability to differing environments. The greater frequency of black squirrels in northern regions, such as the Great Lakes Basin, is thought to be due to the darker fur conferring improved heat retention in colder climates. Despite the difference in appearance, black squirrels remain part of the same species, representing a minor variation rather than a distinct type.