Cottonmouth vs. Copperhead: Watch First Mating Duel Seen in the Wild

Surprising video shows venomous vipers fighting over a female, raising questions about mating between the two species.

Most people would run if they happened across a pair of yard-long vipers twisting and thrashing in the weeds. But Dawn Kelly of Searcy County, Arkansas, reached for her phone.

“I've grown up on a farm and am fascinated by all animals, and in 50-some years of being outdoors I had never seen two snakes interacting like that,” says Kelly, a confectioner and hobby farmer.

But Kelly had no idea just how unusual this behavior actually was until she sent her video to David Steen, a wildlife ecologist at Auburn University who spends his spare time identifying snakes on Twitter and Facebook. “I knew immediately that I was looking at something that was going to blow everybody’s minds,” says Steen.

“It’s unusual to see snakes fighting,” Steen says, “but what makes this observation particularly exciting is that they are two different species—a cottonmouth and a copperhead.”

And that raises another question: Could this be evidence of cottonmouths and copperheads actually mating in the wild? Hybrids of the two closely related species—cottonheads, if you will—have occurred in captivity, but are rarely found in nature.

Cottonmouths and copperheads are both venomous snakes native to the American Southeast. Males of each species are known to perform these types of “ritualized wrestling matches” around this time each year as they compete for females. But males of two different species intertwined in a mating duel? That was something new.

“This observation will change the way we think about how snakes interact with each other,” says Steen.

When Vipers Dance

Gordon Schuett is a herpetologist at Georgia State University who studies these serpentine reproductive bouts.

“Male-male combat in snakes is a behavior that is highly visual and tactile,” says Schuett.

The males writhe against each other rhythmically, twisting in and out of each other’s embrace in an attempt to force the other to the ground. During the mating season, they become so primed and ready to fight that anything that even resembles another male looks like a challenge. In fact, says Schuett, he has even seen a snake tango with a broomstick.

What’s particularly fascinating about these species of viper is that they perform their battles “in a vertical plane.” So while king snakes, pine snakes, and rat snakes do their wrestling on the ground, the cottonmouth and copperhead in the video can be seen rearing up into the air. The result looks as much like a dance as it does a fight.

Once vipers join the fray, they will not disengage until a winner is declared, which happens when a losing snake gives up and is chased away. Kelly can attest to this, as she says she filmed the snakes for around six minutes, with dogs barking nearby, but neither snake seemed to notice her. (Note: Don’t try this at home. It’s best to let fighting snakes lie.)

Schuett’s research shows that the bigger snake usually wins the battle. While the victor goes on to court the female the pair was fighting over, the loser might slither off to lick his wounds for anywhere between 24 hours to up to a week or more before trying again.

In other words, it may look like the snakes are just playing, but we are actually witnessing a serious trial with long-lasting consequences.

WATCH: A cottonmouth duels with a copperhead.

If it’s so important, one might wonder why neither snake tries to bite the other while they skirmish.

“Biting is almost entirely absent in male-male combat in pit vipers and vipers,” says Schuett. Biting is common in nonvenomous snakes, he says, as well as some venomous species such as cobras and mambas.

It’s likely that cottonmouths and copperheads have evolved mating duels where biting is off-limits because they have much longer fangs than cobras or mambas—fangs that could potentially penetrate the victim’s brain, heart, or other critical organs.

Fortunately, whether you’re talking about vipers or bighorn rams, fatalities are rare in animal mating rituals. (Related: Watch “Big Ram Rumble”)

Kissing Cousins

Cottonmouths (Agkistrodon piscivorus) and copperheads (Agkistrodon contortrix) are members of the same genus, which means they are closely related species, and have even been known to mate and produce hybrid babies in captivity.

“When asked what I would call the hybrids,” says Schuett, “I respond tongue-in-cheek, coppermouths or cottonheads.”

But is this video evidence that the venomous snakes are hybridizing in the wild?

It’s difficult to say, since there’s no sign of a female in the video. But it does raise a whole bunch of interesting questions, says Steen.

What species of female were they fighting over? Is it possible there was one of each nearby? What happened when the combat ceased?

“Snakes are very secretive, so they are difficult to observe and study,” says Steen. “It’s always exciting to catch them in action while they are exhibiting unique behaviors.”

As for Kelly, she says, “It sounds hokey but I'm just thrilled I got to share this with others.”

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