A Furry Conundrum: The Dark-furred Squirrels of Winchester

By: Lauren Baker

            Shenandoah University is home to a variety of interesting animals. The most obvious inhabitants are the Gray Squirrels and various avian species, including the infamous geese and a Great Blue Heron. However, among the common creatures that can be seen on campus there is one kind that stands out.

            Our University, along with Winchester itself, is inhabited by a surprisingly large number of black-furred squirrels. They can be seen all over nearby Jim Barnett Park, the main campus, and the rest of the town. And these little mammals have been around for a long time.

            According to local Washington Post columnist John Kelly in his 2011 “Squirrel Week” article, the first black-furred squirrels were introduced to Washington, D.C.’s National Zoo as a gift from Canada in the early 1900s. 

            They were released into the zoo itself, and not as an exhibit. From there, the little creatures have spread.

            By today, it appears that the variant of the Gray Squirrel has reached Winchester itself—for over a decade the black-furred squirrels have been seen on campus and around town. I remember seeing them even as a child.

            But why are the black-furred squirrels black? The answer is simple. Dr. Allyson Degrassi of SU’s Department of Environment and Society explains:

“The “black squirrels” are usually black morphotypes of fox squirrels and eastern gray squirrels. This morphotype exists because there is a variation in the pigment gene”.

            This is referring to the phenomenon of melanism. The opposite of the more notable albinism, melanism occurs when an animal contains more melanin than normal for their species. This leads to creatures with dark or black fur.

            Rafi Letzter expounds upon the science behind the squirrels in his Washington Post Article “Why are there so many black squirrels in the United States? Scientists find the answer”:

“The bit of genetic code that causes the gray squirrel species to turn black…is an allele, or a variant form of a specific gene, called MC1RD24. But that allele doesn’t seem to come from gray squirrels. Instead, they [the scientists] showed, the gray squirrel MC1RD24 allele is ‘identical’ to the MC1RD24 allele found in another species, fox squirrels (Sciurus niger) – one of two mutations that occasionally cause big, reddish fox squirrels to turn black”

            So in fact, the black squirrels of Winchester are likely descendants of interbreeding between the two species. The melanism mutation was passed across species, and over time became a more commonplace variant. 

Interestingly enough, research exists that seeks to discover why the mutation occurs so frequently in the area. According to Dr. Degrassi:

“…the black gray squirrels (melanistic gray squirrels) have an ~11% greater nonshivering thermogenesis capacity than the gray (non-melanistic) ones!…The non-melanistic gray squirrels shiver at warmer temperatures than the melanistic gray squirrels! AND the melanistic squirrels’ rate of heat loss is LESS than the non-melanistic ones by about 18-20%!!!! So, it seems that the black morphology is better adapted to colder climates than the gray morphology”.

In other words, black-furred squirrels stay warmer in cold weather than their gray-furred counterparts. 

The black squirrels have been around for a number of years, and in that time have spread to become a common sight on the average day. These furry creatures are as much a part of the SU community as any one of us.

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