I usually try to do my best in my writing to bust myths about nature, which often stem from anecdotal information that’s not accurate to begin with and is then passed on to others, sometimes for generations. But I realized recently that I had succumbed to a myth that is common here in Virginia — that the eastern ratsnake (Pantherophis alleghaniensis) is a natural enemy of copperheads and will kill any copperheads they meet. It turns out that this is not true.
I started digging into the relationship between eastern ratsnakes and copperheads after a recent encounter with a medium-sized (about 4 feet long) ratsnake that lives around the cabin I’m occupying temporarily on a ridge south of Sperryville. At the time, I was standing in the driveway with a neighbor when I noticed the snake slowly crossing the driveway, heading for the main house on the property. It took a second, but as I stared at it, I realized it was probably moving slowly because of a large lump inside it that stretched out for more than a third of its body. I guessed it was trying to get to refuge under the porch to digest whatever it had just ingested.
Until recently, the common name for this species of ratsnake was “black ratsnake” because of its color. The meal was wide enough to stretch the intervals between the snake’s black scales, giving that portion of its skin a diamond-shaped pattern.
The neighbor and I mused about what the snake might have eaten. Because of the length of the lump, she wondered whether the prey might be another snake, perhaps a copperhead. While, at the time, I did believe ratsnakes killed copperheads, I’d never heard of them eating one. It was time to do some research.
While most of my nature references were packed away elsewhere, I checked the few I had with me that dealt with reptiles. I also scoured reliable sources on the internet, starting with the Virginia Herpetological Society (virginiaherpetologicalsociety.com). What I found is a consensus that ratsnakes actually get along fine with other snake species, even denning up with them in winter. I remembered that a while back I’d read an article that mentioned denning with copperheads, which had surprised me. At the time, I had wondered whether ratsnakes were just less aggressive with other snakes in winter, when they weren’t competing with them for food, but never got around to exploring that issue further.
Eastern ratsnakes kill by constricting their prey. They prefer small rodents and birds (and their eggs) but will also eat lizards and frogs. A couple of sources mentioned that occasionally they might eat a small snake, whatever the species, but most sources didn’t.
What was lying in the belly of this beast? Without killing the snake and cutting it open, I can only guess. While it could have been a nest full of bird eggs (which would be crushed as they were swallowed, so wouldn’t retain their shape) or fledglings, it was getting late in the season for most wild birds that small to be nesting. A rat seemed more likely. Between the constriction the prey went through when the snake killed it, and the further disassembling that was occurring in the snake’s digestive track, the prey would have been stretched out more than before it was eaten.
So how did the myth of the eastern ratsnake’s being aggressive toward other snakes, specifically copperheads, come about? Likely, somewhere along line, adults of this species were confused with two other common snakes that are black and that do kill and eat other snakes: the black racer and the black kingsnake, both also nonvenomous constrictors (see how to tell all three species apart at the Virginia Herpetological Society’s website).
Ratsnakes do have ways to defend themselves and can be quite stubborn and testy when cornered. But in every situation when I didn’t have to confront them (for example, to keep them from getting into my house), I found that they would uncoil and slither away within a few minutes of my getting out of their sightline.
I had mixed feelings about busting this myth about ratsnakes being a potential deterrent to copperheads, mainly because I know that it has saved a lot of ratsnakes from being killed by us humans. All snakes are more our friends than our enemies—especially the nonvenomous ones, such as ratsnakes—because they keep the rodent population in check.
Beyond their usefulness to us, all native species have their place in the food web and are important to the ecosystems they inhabit. In acknowledging the value of snakes, a Virginia statute prohibits killing them unless they are a direct threat, which rules out nonvenomous snakes. I, for one, admire eastern ratsnakes for their beauty, their athleticism, their patience, and when they are threatened, their courage.
(See more about this common yet extraordinary snake, and photos of lots of other local species, at wildideas.us.)
© 2021 Pam Owen
Mysterious wild-bird deaths decline
The mysterious bird deaths I reported in my last column (August 12) as occurring in northern and northwestern Virginia since this spring are declining as mysteriously as they occurred. At the suggestion of the Virginia Department of Wildlife Resources and other public wildlife managers, many people had taken down feeders to keep birds from congregating there and potentially spreading the disease. On August 16, VDWR (tinyurl.com/birddeaths-VDWR) reported that bird deaths were now declining, the contagion apparently ending just as mysteriously as it appeared. The department has lifted its previous recommendation to cease feeding birds in affected areas.
While many known causes of bird illnesses were ruled out by several labs researching the bird deaths, the cause has still not been determined, according to VDWR. The department suggests anyone maintaining feeders or bird baths keep their eye out for dead birds and follow the protocol for maintaining feeders.