As a melanistic variety of the Eastern Gray Squirrel individual black squirrels can exist wherever grey squirrels live. Grey mating pairs may produce black offspring, and in areas with high concentrations of black squirrels, mixed litters are common.The black subgroup seems to have been dominant throughout North America prior to the arrival of Europeans in the 16th century, since their dark colour helped them hide in virgin forests which tended to be very dense and shaded. As time passed, hunting and deforestation led to biological advantages for grey coloured individuals.Today, the black subgroup is particularly abundant in the northern part of the Eastern Grey Squirrel's range. This is likely due to the significantly increased cold tolerance of black individuals which lose less heat than greys. Black individuals also enjoy concealment advantages in denser northern forests.
Large natural populations of black squirrels can be found throughout Ontario, and in several parts of Ohio, Maryland, Michigan, Indiana, Virginia, Washington DC, Wisconsin, Minnesota, and Pennsylvania. Populations of grey squirrels in which the black subgroup is dominant can be found in these six areas as well as in smaller enclaves in New Jersey, southern New York, Illinois and Connecticut. Outside areas of North America where black squirrels occur naturally in abundance, there are several notable introduced populations of Black Squirrels:
Mottled black squirrel in Toronto, Ontario
In the United States, the city of Kent, Ohio developed a significant black squirrel population after 10 were legally imported from Canada in February 1961 by biologist Ralph W. Dexter conducted to study whether they would upset the ecosystem on Northeast Ohio. They have driven out native squirrels in many areas, though they peacefully coexist with most other rodent wildlife
