Curious Silhouettes

Posted in Around the Garden, Wildlife on November 11 2011, by Matt Newman

They’re a curious lot, these dusky squirrels, with their furry ears and black cat sensibilities. You might almost think them bad luck, though even the most superstitious among us would be hard-pressed to toss salt over our shoulders after crossing paths with this forest rodent. And I’m not even sure that’s the right protocol for countering such a thing. Still, these little shadows are worth investigating.

I noticed the black squirrels for the first time while riding shotgun in one of the Garden’s staff golf carts (though the Mosholu course is close, I imagine we only have these because management didn’t take the suggestion of supplying us with go-karts in good humor.) The fellow in the driver’s seat pointed them out as an idle fascination, then asked me if I’d ever seen such a thing. But while a funny sight, there’s initially nothing about their behavior to differentiate them from the eastern gray squirrels you find stuffing capped acorns into their cheeks or, in my case, infiltrating the attic and chewing my home’s wiring threadbare. They breed with the grays, eat the same foods, and in urban areas of the Bronx are just as prone to hassle you for snacks, having grown too accustomed to people.

The damage caused by my home’s squirrel infestation and consequential fire hazard may still be fresh, but the black squirrel’s presence in the city is less so. It was back in the ’70s that these chittering strangers started appearing here. Few knew where they’d come from, fewer still why the Bronx became their home (though plenty of suggestions and conspiracies can be found online). They simply popped up here at the Garden and around Fordham University’s campus, scrambling about with the rest of the grays as though they’d always been here. And, in a virtual sense, they always had.

Contrary to common belief, the black squirrel isn’t a breed of rodent distinct from its gray relative. You can glance over the scientific names of the two to see that they’re one and the same–Sciurus carolinensis. The darker variation is what scientists like to call a “melanistic subgroup,” which can be thought of as the opposite of albinism. The inky fur is a result of high concentrations of melanin, the same pigment that gives a sunbather that perfect tan, though in this case the aesthetic is a bit more permanent. The black panther (commonly a jaguar or leopard, depending on the region) is the prime example of melanism. Of course, trying to relate a squirrel to such a regal predator is laughable, but the genetic peculiarity is the same.

The explanations for why the black squirrel came about are almost too many to list. Arbitrary genetic mutation, temperature changes in the mother’s habitat, and adaptive evolution are each cited as a possible cause; some even suggest that the black squirrel is a holdout from primeval forests. But regardless of origin, the melanistic squirrel has thrived here in the Bronx for the past four decades, to the point that some believe they make up a good 40% of the squirrel population in certain areas. This is because each black squirrel has the opportunity to pass on the melanistic trait through breeding, which explains how they’ve slipped the bounds of our borough and cropped up in Central Park over the last five years.

That’s the science of it in a layman’s nutshell–of these oddly conspicuous puffs of shade standing in such sharp relief as they bound through the grass. And while it’s still up for debate as to whether they’re any different from their gray siblings–some say bolder, more brazen, maybe even mean–there’s nonetheless a mystique to the black Bronx squirrel, not at all alien and yet so very foreign. Even as pedestrian as they are to Bronx natives, they manage a sort of comical beauty.

In the midst of all this greenery, it’s a pleasant surprise to come upon the occasional display of wildlife flitting between the trees. Even the genetically curious examples. Feel free to leave a comment below about your favorite NYBG wildlife sightings, and tell us what it is you love to see wandering the grounds.