Eastern Ratsnakes and Copperheads: Foes or bros?
Updated: Jan 23, 2022
Busting a myth
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 (here, the Eastern Copperhead, (Agkistrodon contortrix) 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 Eastern 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 Amateur herp lover Mike Van Valen offers a good explanation for changing the species common names of ratsnakes from being based on color to being based on geography in "The Ratsnake Mess for Dummies," on his Herp Unit website. (Spoiler: The culprit for the "mess" is the advent of DNA technology, which has been shaking up the taxonomic world since testing became available.) The meal the snake in question had eaten was wide enough to stretch the intervals between its 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. What I found is a consensus that ratsnakes actually get along fine with other snake species, even denning up with them in winter, and that includes copperheads. I remembered that a while back I’d read an article that mentioned the 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 until this recent snake encounter.
Food for thought
So what was lying in the belly of this beast? Without killing the snake and cutting it open, I can only guess. Ratsnakes kill by constricting their prey. The digestive enzymes of snakes are strong enough to dissolve bones and egg shells, leaving only hair, claws, insect shells, and other indigestible matter to be excreted. 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.
While it could have been a nest full of bird eggs (which would be crushed as they 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.
A famous literary pondering of snake digestion
The question of what was inside the snake reminded me of one of my favorite books when I was learning French as a child: Antoine de Saint Exupéry's Le Petit Prince (The Little Prince). In chapter one, the narrator explained that, as a child, he had shown a picture to grownups that, at first glance, looked like a hat — at least to the adults.
“My drawing was not of a hat," the narrator explains (English translation). "It showed a boa constrictor digesting an elephant. I then drew the insides of the boa constrictor, so that the grown-ups could understand. They’re always looking for explanations.”
My takeaway, as applied to the ratsnake situation covered in this piece, is that it takes a bit of imagination, along with a general knowledge of biology, to try to figure out just what a lumpy snake has ingested. By the way, the largest animal documented to have been consumed by a constrictor is a 130-pound impala, eaten by an African Ppython in 1955, according to LiveScience. (See the original text of Le Petit Prince, in French, with the author's original illustrations, at Project Gutenberg Australia.)
How the myth came about
So where did the myth about the Eastern Ratsnake’s being aggressive toward other snakes, specifically copperheads, come from? 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 (which is common throughout Virginia) and the Black Kingsnake (only found in southwest Virginia), both also nonvenomous constrictors. (See how to tell all three species apart at the Virginia Herpetological Society’s website.)
Although the Eastern Ratsnake, like most snakes, would prefer to avoid confrontation, when threatened, it has some tricks for scaring off potential predators:
· Inflate its head to mimic pit vipers, such as a copperhead or rattlesnake, which are venomous
· Shake its tail on the ground to sound like a rattlesnake
· Coil itself up, raising its head as high as it can and look ready to strike
· Excrete a foul musk when touched and spread it around with its tail
Excreting a repulsive substance is also common among some other reptiles, including ring-necked snakes, which I picked up often as a child because they were ubiquitous around my home in Fairfax County, small, pretty, and generally docile. Remembering the stink, I’d almost prefer to be bitten.
I’ve gotten within a foot or two of ratsnakes, to photograph them, without their striking. I picked them up often as a child, out of curiosity, and a few times as an adult to deter them from coming inside the house. I’ve only been bitten twice, when I was not quick enough. Once was a few years ago when a six-footer got into my house and had quietly coiled up on a table, watching me from about six feet away. I wanted to get it out before my dog, which was close by, figured out the snake was there.
Unfortunately, the snake seemed to realize my intent and was starting to move before I could reach it. Afraid it would disappear somewhere in the house or attract the attention of the dog, I grabbed for it—but not quickly enough to avoid being bitten. The bite is mild and, since this species is not venomous, application of an antibiotic ointment is all that is needed to make the wound heal quickly. With the intruder, I adjusted my grip and carefully dropped it off my deck, which was only a few feet off the ground.
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.
© 2021 Pam Owen