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Rattlesnakes Might Be Changing In Black Hills


In the summers, many visitors enjoy the Black Hills’ hiking trails and take in the sites. There aren’t many animals in our region that pose a threat to humans. In fact, one of the few species to look-and listen-for are rattlesnakes. However, there may be something about rattlesnakes that’s evolving-but snake experts disagree.  

Many people say when they hear this sound…


The hair on the back of their neck stands up. It’s the warning sound rattlesnakes make by shaking the tip of their tails. Listening for that can help prevent a venomous bite. 

“Yeah they’ll rattle basically as long as they feel like they’re threatened and it’s typically motion induced. And if we stop moving for a second then that rattling stops.”

Terry Philip is the curator of reptiles at Reptile Gardens-a wild animal park in Rapid City with all sorts of reptiles, bugs and birds. Philip has been working with snakes for more than 30 years. 

He’s heard plenty of myths about the snakes. One suggests that  baby snakes have more venom. Not true. Philip says the amount of venom depends on the size of the snake and how much the snake injects during a bite. Also, contrary to another myth, Philip says  rattlesnakes do not cross breed with any other snake species. There’s another myth Philip has heard about rattlesnakes -- that they always rattle before they strike. 

“After all these decades, all these years of working with rattlesnakes, probably 10’s of thousands of rattlesnakes have come through my hands at one point or another. And I’ve never once seen a rattlesnake stop and ask permission from his butt to bite. That is totally untrue. Some rattlesnakes will bite and then rattle, some will rattle and not bite. There is just no connection between the two.” 

Philip says rattlesnakes typically have a strong muscle underneath their rattle. He says a normal rattlesnake uses that muscle to make the warning sound. But in the past few years, Philip has had encounters with rattlesnakes that don't rattle at all. 

“I’ve noticed a trend in the local population of rattlesnakes here in the Black Hills of a genetic defect that is passed on from parent to offspring.”

Philip says almost half of the snakes he’s encountered have what he calls a curly-Q tail. 

“So that musculature that would normally operate the tail is atrophied and/or largely just absent. The rattle has very little support to it and it kind of curls up over the top of their back. And the rattlesnake, he still wants to try to rattle it. He still shakes it. There's just no musculature there to produce a sound. The rattle is in essence, fairly useless.” 

Philip says some of the Prairie Rattlesnakes that make the rattling noise, have been killed by people. He thinks the rattles may be changing as an evolutionary tactic to save their lives. 

“And so the ones that we’re leaving alive because we don’t find them are the ones with this atrophied, genetic defect. And so if anyone ever needed a reason to not kill the next rattlesnake that they encounter, this is it. Because by killing all of the good rattlesnakes that genetically produce other rattlesnakes that make noise. Those are the ones we’re offing and we’re leaving this population of animals that doesn’t have a good alarm system.”  

Philip says it’s important to remember that only a small portion of the Prairie Rattlesnake population is found in the Black Hills. They’re native to the Western United States and Southwestern Canada. Philip hasn’t heard reports of curly-Q Prairie Rattlers in other areas, but he says some rattlers in Texas have been reported to rattle less often or not at all. 

“You adapt or die. They are running along a course that is adapting them to a better survival strategy than the alarm system.”


Not all scientists agree that this is a sign of evolution. Wayne Thompson is a Physical Science Technician at the Badlands National Park. 

“I actually haven’t heard it and I certainly haven’t seen it in the rattlesnakes that I’ve encountered out here and certainly not in the Hills either.”  

But Thompson says it IS possible that Prairie Rattlesnakes in the Black Hills could be passing on a new trait. He says genetics does all kinds of crazy things. 

“If it were to be something that provided them with some kind of benefit, it may be passed onto successive generations even if it’s not exactly some type of genetic abnormality. If that abnormality is passed onto successive generations, then year I think we would probably see more in the population that have these curved rattles, I just haven’t seen it.” 

Thompson says even if a rattlesnake can rattle, it won’t always. 

“The Prairie Rattlers we have here-I mean some do, some don’t. I think it depends on how close you get. How much they determine that you’re a threat. I guess there could be a number of factors that would determine whether or not these guys would rattle or not.” 

Black Hills State University herpetologist, Brian Smith has also not seen the curly-Q tail in rattlers.

“In general what rattlesnakes will do it hide and stay away from you unless they feel threatened in some way, in which case they’ll start rattling. I don’t know of any rattlesnake that can’t rattle, I’ve never seen one.” 

Smith says he’s found rattlesnakes that have lost the rattle portion of their tail, but that’s as close as his research has shown. He says they don’t rattle unless there’s a need to. 

“They're interested in eating warm blooded prey and they’re very good at finding warm blooded prey and warm blooded things that are not prey are things that they generally want to avoid. So they don’t rattle and stay on a rock or something, but if they’re discovered, then they will.” 

Even though regional snake experts haven’t all seen the curly-Q tailed rattlesnakes, they all  agree on safety techniques in the field. Don’t ever try to catch or touch the snakes, and when you hear this sound…


Walk away.