A Squirrely Show of Color

The black squirrel stopped me in my tracks.

Black is a common color morph in eastern gray squirrels, especially in northern areas like Ohio, Michigan, and Ontario.

But this black squirrel had a most uncommon feature: a cinnamon-colored tail.

Despite the name, eastern grays vary from all gray to reddish to all black. Most have cinnamon hairs in the mix, ranging from barely visible highlights to big red splotches. I see the unusual squirrel often enough to study its pelage. In bright sunlight, cinnamon slivers shine in its black fur, and the tail fades somewhat, as though over-exposed in a photo. But the odd color combo is real, not some trick of lighting.

In 2019, researchers found a faulty gene that explains black fur in a normally gray squirrel. They believe the color-changing mutation originated in fox squirrels but spread to gray squirrels through interbreeding. Is my bi-colored neighbor the product of such a coupling?

Probably not. The interbreeding that introduced black pelage (formally known as ‘melanistic’) to gray squirrels is apparently ancestral, not recent. Scientists suspect that the black variant has flourished in northern climates because dark fur provides an evolutionary advantage of retaining heat in frigid weather.

In addition, several resources say that fox and eastern gray squirrels are unlikely to live in proximity. The eastern grays prefer forests. The fox squirrels gravitate to areas where forests meet clearings, like woods at the perimeter of a farmer’s field.

Even in urban areas, these squirrels tend to choose dissimilar habitats. That insight comes from a citizen-science initiative called Project Squirrel, which was begun by Dr. Joel Brown of the University of Illinois-Chicago. The project collects data used to catalog the eastern gray and fox squirrels’ habitat preferences. More than 1,000 project participants have observed squirrels and reported their whereabouts online since 1997 (including me, as of last week).

If you’re wondering whether a red squirrel might be in the mix, that’s unlikely. They’re rarely melanistic, considerably smaller than the grays or foxes, and they don’t interbreed.

So, back to my two-toned neighborhood squirrel. The Squirrel Project website has a page for photo sharing, where I found the final word on the animal’s unusual color combo. Someone posted a photo of a similar squirrel, and the project team weighed in: Melanistic grays tend to have black bodies and tails, but can sometimes have gray, orange, or even white, tails.

My neighbor, therefore, is without a doubt a melanistic eastern gray squirrel. That is not to suggest identifying squirrels has become totally cut and dry for this amateur naturalist. Here’s a squirrel whose cinnamon-colored belly had me shaking my head in confusion.

Do you see squirrels of many colors? Let me know in the comments. And do consider joining the Squirrel Project.

RESOURCES
In addition to the Squirrel Project link I posted above, here are some great articles that helped me nail down Mr. Cinnamon-Tail’s identity:

Read about the squirrel genetics study in Smithsonian Magazine online.

Gray squirrels’ fur changes color seasonally. Learn more in an article published by the State University of New York’s College of Environmental Science and Forestry.

Here’s an article about the role evolution plays in advancing the black squirrel population. I found it interesting that researchers note there’s evidence of black squirrels in Ohio dating to the 1760s.

Read an interview with Dr. Joel Brown and watch a fascinating video where he talks about his gray v. fox squirrel study.

Here’s a short explanation of why red and gray squirrels do not interbreed.

RELATED KIDS’ BOOK

Squirrels Leap, Squirrels Sleep, by April Pulley Sayre, illustrated by Steve Jenkins.
This beautiful picture book invites young children to explore the busy life of a squirrel. With spare, rhyming text and beautiful art, each page shows some aspect of a squirrel’s daily activity. There’s mention of several kinds of squirrels, with lots of visual habitat clues. Back matter adds scientific detail that will engage older kids. A terrific book to introduce and learn about an animal most kids will encounter from a very young age. Here’s a link to find the book.

Image Credits: Carol Doeringer.