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Science

Rattlesnakes That Can't Rattle Being Found In The Black Hills

Prairie_Rattlesnake.png
Steve W. Thompson
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(The following story originally aired on August 29, 2013.)

South Dakota is home to only one venomous snake—the Prairie Rattlesnake. They can be spotted in every county in the state west of the Missouri River, and in a spot or two along the river in the east.  A growing number of these snakes appear to have lost their ability to rattle, and that concerns some scientists who think the abnormality may lead to that very obvious warning of danger eventually going away.

On a nice day during her senior year of high school, Bonny Fleming decided to take a walk in the Black Hills.

“I had left school for lunch, and I was all by myself, and I went to a remote place that I like to go in the Black Hills. And I had traveled up a trail, and there was a rock outcropping, and I went to sit on that rock, but I just kinda hopped over it," Fleming says. "And there was a rattlesnake right under my legs. And it rattled, and I was able to spook it, and it just went back into its little hole.”

It was Fleming’s first encounter with a rattlesnake, which left her alone once it fired its warning rattle.

The sound made by Crotalus Viridis¸ or the prairie rattlesnake, is one of the most chilling sounds heard in nature. There’s a specific purpose to the rattle: to keep larger animals and humans away. But Terry Phillipp, naturalist at Reptile Gardens in Rapid City, says that signal usually means the snake’s demise.

“Every rattlesnake that gets discovered generally gets killed. And the snakes that are discovered generally have a really strong muscle next to their rattles, so that they actually function the way they’re supposed to," Phillipp says. "So people will be out walking or gardening or whatever, and the rattlesnake gets to rattling—well, it gets the end of the shovel or the .22 pistol or whatever.”

Over the past couple of years, Phillipp has noticed many rattlesnakes with what he calls “curly-Q” tails.  Imagine the tail on a pig, and you’ll get the idea. Phillipp says the tail muscles on these snakes have atrophied, and accordingly, can’t move the rattle. Rattlesnakes can camouflage themselves well, and, if they’re not heard, they’re likely not killed.

“And so the snakes that have that genetic defect—it is a genetic defect—those are the ones that are surviving," Phillipp says. "They then reproduce, and they pass along that genetic defect to their offspring.”

Phillip’s theory is that if the rattlesnakes that announce themselves are spotted and killed, those with the defective tails are breeding and creating more snakes that can’t rattle. 

Bonny Fleming, the hiker who encountered a prairie rattlesnake in high school, says she understands what a dangerous situation that could be for those exploring the Black Hills.

“I think that’s terrifying," Fleming says. "Every encounter I’ve had, I’ve been able to avoid them because of that warning. So it’s really helpful, and I think it’s helpful for them, too, because it keeps the people that are scared of them away.”

Like all snakes, rattlesnakes only bite humans as a last resort; they’d rather not waste venom on something that’s too big to eat. Todd Magnuson, who co-hosts the cable TV outdoor show “Nature Adventures,” says the snakes have other ways to avoid detection before resorting to a strike.

“The first thing they do is, they really try to flatten themselves out, and try to use camouflage, and not—and not strike, and not rattle their tails, and really suppressing that and not make any noise so you don’t know you’re there," Magnuson says.

Magnuson isn’t quite in line with Terry Phillipp’s theory on a genetic defect in the snakes. In a cage in his garage in the small town of Trent, Magnuson has a prairie rattlesnake he found south of the Badlands about three years ago. The snake’s tail was curled when Magnuson found it, but, in captivity, the tail has straightened and rattles the way it’s meant to. That tells Magnuson the curled tail may be a process of evolution.

"And I don’t have anything scientifically to back this up," Magnuson says. "But I really think just from observing that the rattlesnakes are developing this behavior, because 200 years ago, the Native Americans were the only people in South Dakota. And a rattlesnake would rattle and they would respect it and leave it alone. Well, the white settlers moved in, and when a rattlesnake rattles, it gets them instantly killed.”

Black Hills State University professor Brian Smith has made a career out of researching rattlesnakes; he has about 15 to 20 prairie rattlers behind a locked door on the Spearfish, South Dakota campus. While being careful with any confirmation, Smith says there’s no reason not to think some snakes just can’t rattle.

"I haven’t seen that film or anything, so it’s impossible for me to say. But snakes do get abnormalities; they do get their tails broken during failed predation attempts," Smith says." It’s hard to say without seeing the film or photo what’s going on.”

This is not to say a snake has to rattle before biting. It’s also not to say you shouldn’t be aware of your surroundings when rattlesnakes may be present. Smith, who himself has never been bitten by a venomous snake, says it’s something no one wants to go through.

“There’s been a few fatalities recorded in South Dakota over the decades, but deaths from prairie rattlers are pretty rare. You might get a little bit more than a dozen deaths from venomous snakes in the United States in a year, so it’s really unlikely people are going to die from rattlesnake bites,” Smith says.

When someone is bitten by a rattlesnake, the old wives tales about having someone suck out the poison, drinking alcohol, and other methods many believe will work won’t. Brian Kenner is Chief of Science and Natural Resources at Badlands National Park.

“The best thing is to get help right away and get taken to a hospital and get antivenin, which is what happened to a snake bite victim here this summer. They got her to a hospital and got her antivenin as quick as possible, and she’ll make a full recovery,” Kenner says.

Herpetologists say the rattlesnakes are more than happy to leave you alone if you return the favor. And with common sense, careful observation and watching where one puts their hands and feet, the chances of being bitten by a rattlesnake are really pretty small.