by Greg Mayer

Squirrels are, of course, perennial favorites here at WEIT, being known as honorary cats. They also present a number of interesting phenomena of within and among population variation in easily observable traits like pelage color. Because these variations are often known even to casual observers, I often use squirrels as examples when explaining what species are. In eastern North America, gray squirrels, fox squirrels, ground squirrels, chipmunks, and woodchucks provide many informative examples of the differences within and among species.

We’ve had occasion to comment here on albino, parti-colored and black squirrels, all of which are gray squirrels (Sciurus carolinensis). I was thus intrigued when my Toronto correspondent sent along a photo, taken in Port Huron, Michigan, of a black squirrel with a brownish tail.

The body looks like a typical melanic squirrel– black, although when seen up close, they often have some reddish/brownish in them– but the tail is brown! Black is usually the result of the pigment eumelanin, while browns and reds often are due to the presence of phaeomelanin, so melanics can have both pigments present. In the Port Huron squirrel, the tail (although not the underside of the base, which is black) perhaps has only phaeomelanin. There were “tons” of regular melanics in Port Huron, but just one with the lighter tail.

I have seen melanics and albinos in the wild, but I had never seen– in the wild, in a museum, or just in a photo– a melanic with a brown tail. I consulted a colleague with a great deal of field experience in Wisconsin, especially northern Wisconsin, and he too had not seen them. I was surprised to learn after consulting a standard reference (Fiona Reid‘s volume on mammals in the Peterson Field Guide series– highly recommended) that such squirrels are in fact well known, especially from further north in the range of the squirrel.

My Toronto correspondent also sends a photo of a black squirrel from Toronto itself. Black squirrels are quite common in Ontario: my correspondent writes, “[I]n Toronto, I feel as if I see a black squirrel every time I turn around!” The interest of the pictured squirrel is that it seems to have light spots on the forehead and back; she said it looked “spotted”.

You can see the white spot on the forehead; there’s another, just barely visible in this photo, in the middle of the back. I have never seen this pattern either. I did find though, through a link provided by Jerry, the opposite pattern: a photo of a white squirrel with darker spots on forehead and mid-back from Brevard, North Carolina, where white (and mostly white) squirrels are common.