Black squirrels can exist wherever grey squirrels live. In some cases black squirrels will kill baby fox squirrels. 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 abundant in some areas. The significant increase is due to greater cold tolerance of black individuals which lose less heat than grey squirrels. In some areas black squirrel have driven out native squirrels, though they peacefully coexist with most other rodent wildlife
