As a melanistic variety of the eastern grey
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.[1]
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.[2]
Today, the black subgroup is particularly abundant in the northern part of the
Eastern Grey Squirrel's range.[3][4]
This is likely due to the significantly increased cold tolerance of black
individuals which lose less heat than greys.[5]
Black individuals also enjoy visibility advantages in denser northern
forests.[1]
Distribution
Large natural populations of black squirrels can be found throughout
Ontario, and in several parts of Michigan, Indiana, Wisconsin and Ohio.[6]
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.[7]
Outside areas of North America where black squirrels occur naturally in
abundance, there are several notable introduced populations of Black
Squirrels:
In the United States, the city of Kent, Ohio has a
significant black squirrel population, after 10 were legally imported from
Canada in February 1961. They have driven out native squirrels in many areas,
though they peacefully coexist with most other rodent wildlife.[8]
Black squirrels are well established on the Illinois side of the Quad
Cities. They are mostly found in the city of Rock Island. According to one
story, recounted in the book "The Palmers," they were first introduced on the
Rock Island Arsenal Island. Some of them then escaped by jumping across ice
floes on the Mississippi River when it was frozen and populated other areas in
Rock Island.[9]
Fort Mitchell,
Kentucky, maintains a significant population of black squirrels after
several were introduced from Detroit prior to 1977[11]
Black squirrels were introduced to Stanley Park in Westfield,
Massachusetts, in 1948, having been brought from Michigan as a gift to a local
business man. The squirrels thrive in the park to the present.[12]
Marysville, Kansas,
has a notable population of black squirrels which legend claims arrived there
by escaping from a travelling circus.[13][14]
The city of Hobbs, New Mexico
attempted to introduce black squirrels from Marysville in 1973. However, the
new population of black squirrels did not survive, likely having been killed
by local fox squirrels shortly after their introduction.[13]
Black squirrels were introduced to the Washington, D.C.,
area near the beginning of the 20th century at the Smithsonian
National Zoological Park. Since their introduction, the population of
black squirrels in Washington has slowly but steadily increased, and black
squirrels now account for up to 25% of some squirrel populations in the
area.[15]
Vancouver, British Columbia, has
a growing population of black squirrels after they were introduced to the
Stanley Park Peninsula before 1914. The squirrels have thrived and spread
throughout the Vancouver area.[16]
Black squirrels can also be found in Britain where grey squirrels were
first introduced from North America at the end of the 19th century.[17]
The origin of the UK's black individuals has been a topic of dispute, with
initial research indicating that melanistic individuals are descendants of
black zoo escapees.[18]
Regardless of their origins, the melanistic population in the UK continues to
grow, and around the towns of Letchworth, Stevenage
and Hitchin,
as well as nearby villages such as Meppershall in England, black
squirrels are now as abundant as grey individuals.[19]