How the black squirrel's coat gives it an edge in Canada
Black squirrels are a familiar sight across parts of Canada, including Toronto, Calgary, and Vancouver, so you might be surprised to find out they might not be here without their distinctive colour.
It's a mutation of a pigment gene that can happen in both grey and fox squirrels that makes their fur black -- a condition known as melanism. One copy of the alternate pigment gene makes the squirrel brownish-black, two copies result in jet-black fur.
A recent study showed that England's black-furred grey squirrels have a faulty gene identical to the one found in black fox squirrels (which are native to North America.) The researchers believe interbreeding between the closely-related species spread the mutated gene from fox to grey squirrels.
Lead researcher Dr. Helen McRobie says that the 'mutant' gene may also give the darker squirrels the edge when it comes to colder climates, including here in Canada.
"The fact black grey squirrels have become so common right across North America is possibly because black fur offers a thermal advantage, helping them inhabit regions with extremely cold winters," said McRobie in a news release. "This may have contributed to the expansion of the grey squirrel's range during the past 11,000 years, following the end of the most recent ice age, helping them spread further north into Canada."
Sources: EurekAlert | Journal of Heredity | Anglia Ruskin University |
