Sept. 27, 2024

Hardly any animal in North America inspires the mix of fascination and fear that people feel for rattlesnakes.

People often kill rattlesnakes without a second thought and even have community events to gather and kill them. 

And yet in the American Revolution, there was a kind of respect for the timber rattlesnake that would rather use its rattle to warn an enemy than strike. The snake was depicted on the Gadsden flag as a symbol of the unity of the colonies, warning outsiders “Don’t tread on me.”

Not that colonists were fans of the actual animal. Indigenous people were said to have misled settlers about the locations of rattlesnake dens to keep them from destroying them. In many Native American cultures, rattlesnakes have been seen as spiritually significant, though sometimes as associated with witches and capable of avenging the killing of other rattlesnakes.

The timber rattlesnake symbolized the original 13 colonies on the Gadsen flag, created by Richard Gadsden in 1775 during the American Revolution. Courtesy of Wikimedia Commons.

The revered American folklorist J. Frank Dobie wrote about these reptiles, including tales told by rural folks, Mexicans, and Native Americans, in Rattlesnakes. The cover of my copy has the subtitle: The Age-Old Feud Between Snake and Man.”

Rattlesnakes by J. Frank Dobie originally published in 1982. Courtesy of University of Texas Press.

Let’s take a look at the real story of the rattlesnake, including some accurate information about size, rattles, venom and behavior. We will get a glimpse of human-snake interactions both out in ranchland and desert and as told in Texas folklore.

A FAMILY OF VIPERS

Rattlesnakes are vipers, a world-wide family whose members have fangs (a pair of long, hollow teeth) in the front of the mouth through which they can inject venom. 

More specifically, rattlers are “pit-vipers,” that is, vipers with a heat-sensitive “pit” in the face between the eye and nostril. Within the pit is a membrane, filled with receptors that are sensitive to infrared, i.e. heat. Nerves from those receptors travel up to a part of the brain that decodes vision, and so a pit-viper “sees” patterns of warmth against a cooler background. A rattlesnake waiting in ambush on a dark night can see a mouse just by the heat of the mouse’s body. The pits can also help them find a slightly warmer refuge that will protect them on a chilly night. The pit-vipers include rattlesnakes, copperheads, cottonmouths, and a few other species outside the U.S.

Rattlesnakes range all the way from Canada to South America. They are diverse in size, pattern, and the kinds of habitats they require to thrive. The sidewinder, for example, is a small rattlesnake that is adapted to living in sandy deserts and moves around by “throwing” coils of its body to the side and forward so that it can move across the sand. 

The group of rattlesnakes in the genus Crotalus tend to be somewhat larger than the pygmy and massasauga rattlesnakes in the genus Sistrurus. Crotalus includes several Texas rattlesnakes: the western diamondback, the timber, prairie, black-tailed, Mojave and rock rattlesnakes. Only the western diamondback and timber rattlesnakes can be found in the vicinity of DFW. 

Of the Sistrurus genus, the western pygmy rattler lives in parts of the eastern half of Texas while the western massasauga lives mostly in the western half of the state. As it turns out, both of these smaller rattlesnakes can be found in a few places near Dallas-Fort Worth.

A western pygmy rattlesnake, our smallest species in Texas. Photo by Michael Smith.

THE RATTLE

Rattlesnakes are, of course, defined by their possession of a rattle. Although many snakes vibrate their tails when nervous or threatened, only rattlesnakes have a rattle. It is a series of dry, interlocking, hollow segments at the tip of the tail which make noise when shaken. It is made from the same material as your fingernails.

Sometimes if the snake is just a bit nervous, the tail twitches and makes an irregular series of clicks. Once, standing in some roadside grasses in West Texas, I heard just such a sound. My friends and I immediately froze in position, searching for the rattlesnake. The big danger comes from accidentally stepping on one. As soon as we located it, we could step away in safety, thankful that this snake alerted us to its presence. 

Once a rattlesnake is thoroughly alarmed, the tail is vibrated amazingly fast, from 60 to nearly 90 cycles per second. Think about it – more than 60 times every second. The muscles and tail structure are specialized so that they can work at that speed for extended periods of time. The resulting sound, as the segments are shaken against each other, may sound like high-pitched buzzing. To me it suggests the sound of frying bacon.

A diagram of the rattle, with a section cut away to show how the segments loosely interlock. Illustration by Jack Jeansonne, from The Wild Lives of Reptiles and Amphibians. Published by Texas A&M University Press. 

We have all learned that the rattle serves as a warning. The usual example is deer or bison, which might notice the sound and avoid stepping on the snake. It makes good sense, but in his book, Snakes: The Evolution of Mystery in Nature, snake researcher Harry Greene has said that the earliest rattlesnakes probably used the rattle to warn away predators that probed into rock crevices where the snakes were hiding.

Are rattlesnakes losing the ability to rattle? A recent myth has it that rattlesnakes are evolving so that they don’t rattle so much. The reasoning is the noise might attract predators like feral hogs. Whether you survive and pass along your genetics to the next generation is the engine that powers evolution. What would it take for the myth to be true? If the snakes who stayed quiet were more likely to survive and produce more young, then future generations might be less likely to rattle. 

I checked with Rob Denkhaus, who during his 26 years of leadership at Fort Worth Nature Center and Refuge studied wild pigs and became a recognized expert on these animals. He told me that while feral pigs will eat lots of things, rattlesnakes are not a major part of their diet. Further, they do not hunt primarily by hearing noise from prey. And so, feral hogs should not affect the rattlesnake’s willingness to rattle.

Each time the rattlesnake sheds its skin, another segment is added to the string of segments. Another myth is that you can tell the age of a rattlesnake by counting the rattles. Since the snakes shed multiple times a year, you cannot tell the age of the rattler by the number of segments. Not only that, occasionally the rattle will get hung up on a branch or a rock and a few segments will break off.

GIANT RATTLESNAKES?

J. Frank Dobie quotes a claim from the mid-1800s of a Texas rattlesnake that “measured seventeen feet in length, eighteen inches in circumference,” and had 25 rattle segments. Dobie acknowledges that “the way to make a record in snake-killing is to be off away from tape measures or yardsticks or scales and not have too many witnesses.” He accurately reports on how big rattlesnakes can get, with the western diamondback having an official record length of about seven feet. In their field guide, Texas Snakes, James Dixon and John Werler agree, while noting that the ordinary ones are about three or four feet long.

What about the enormous rattlesnakes you see on Facebook, dead and hung over a stick or a hook, held close to the camera. They may not claim that it is 17 feet long, but they may say “look at this 12-footer we killed at our hunting lease.” It’s never that long, but if you position the snake some distance in front of the person, a trick of camera perspective makes the snake look huge.

A timber rattlesnake. Southern populations are also called "canebrake" rattlesnakes. Photo by Michael Smith.

None of the other rattlesnake species in Texas grows as long as the western diamondback, though the timber rattlesnake runs a close second. Out in West Texas, the rock rattlesnakes are considerably smaller. Of the two smallest rattlesnakes, the massasauga and pygmy rattler, the latter is the smallest with an average length of 15 to 20 inches.

RATTLER ATTITUDE

Years ago, while out in the Trans-Pecos near the Diablo Mountains with Clint King (co-author with me of Herping Texas), we came upon a western diamondback on the road. We pulled over to get the snake off the pavement before it got hit, but first I snapped a photo. The snake was sitting perfectly still and flattened out, stressed at being confronted by a human. 

I went back to the car, got a snake hook and returned to move this rattlesnake. It was still flat and motionless, and I should have paid better attention to this indicator of how tense the snake was. The moment the hook touched the snake, it sprang into action, rattling and striking. It was crawling toward me and each strike launched it closer to me as I back-pedaled out of the way. As soon as I was able to step aside, the snake kept going off the pavement and out into the desert. We both got through a scary encounter safely.

Here's what almost certainly happened: Confronted with something big and dangerous like a human, snakes tend to either freeze (as if hoping they will not be seen) or attempt to get away. If that fails, they may bluff or warn the intruder, or if the snake judges that it must, it will bite. This rattlesnake may have tried freezing, but when touched it responded defensively while trying to get away in the direction it figured was best. While I was in the way I easily could have been bitten, but once its escape route was clear, it stopped “attacking.”

Since I have been going out in the field for well over 50 years, I’m sure I have walked past many venomous snakes that could have bitten me, even though I’m pretty observant. Confrontations are extremely dangerous for the snake, and venom is a valuable asset that they don’t want to spend if it’s not necessary. No matter how dangerous the snake, most of the time they try to hide or get away. 

Studies that simulated contact with cottonmouths and with rattlesnakes have shown that these snakes often do not bite even when lightly stepped on. 

None of this means that rattlesnakes are gentle or friendly toward us. They just want to be left alone. People should respect the potential danger and keep their distance. 

VENOM AND SNAKE BITE

A western diamondback rattlesnake. Photo by Meghan Cassidy.

Venom, and the fangs for injecting it, is an evolutionary gift to rattlesnakes that enables them to eat mice, rats and other small mammals with minimal risk of counterattack by the rodent. The snake bites and lets go, and then tracks the dying prey and swallows it when it is dead. Because many of the proteins that make up pit-viper venom are designed to break down tissue, the venom starts the process of digestion from the inside out, before the rat is even swallowed.

It is also a potent defensive weapon, though maybe not so powerful as the various tall tales claim. Dobie recounts one story in which a man tries to kill a rattler with a hoe. The snake strikes, missing the hoe and biting a fig tree, which subsequently dies. Another popular tale involves a rattlesnake biting a cowboy’s boot, killing him and leaving a fang embedded in the boot. When someone else later puts on the boot, they are scratched by the fang and promptly die. 

Those folk stories elevate the rattlesnake’s power to near mythic proportions. The reality is that with proper treatment, venomous snake bites in the U.S. are rarely fatal. In Venomous Snakes of Texas, Andrew Price cites statistics over a nine year period showing five deaths from snake bite in Texas, compared with 79 from venomous arthropods (bees, scorpions, and the like). Even lightning strikes produced more fatalities than snake bite. 

Low mortality does not mean that venomous snake bite is a minor thing — a pit viper bite is always a medical emergency. It is usually extremely painful and can be disfiguring. Typically it results in swelling that can be severe, bruising, blood abnormalities and other symptoms. 

For any significant envenomation, the definitive treatment is the intravenous administration of antivenom. This medicine is made using venom extracted from pit vipers and involves antibodies that bind with the venom in the victim’s body, neutralizing it.

WHAT IS THEIR FUTURE?

A young western diamondback rattlesnake. One of the heat sensitive pits is visible in front of and below the eye. Photo by Michael Smith.

How will we continue to interact with rattlesnakes? And as more of us live in cities and development claims more natural spaces, will encounters with rattlesnakes be rare? Can we co-exist — with caution and a little space — with these reptiles? 

The International Union for Conservation of Nature is composed of over 1,400 organizations, both governmental and civil. The IUCN keeps a list of species showing their status in the wild, called the “redlist.” 

The redlist shows that status of the western diamondback, timber, massasauga, and pygmy rattlesnakes are of “least concern.” It does note that the timber rattlesnake is decreasing and the massasauga’s population trend is unknown. And so, given suitable habitat and climate, it appears that the snakes will persist into the future. 

Will we still see them and come up with stories to try to explain what we see? Many of us hope for a continuing relationship with these snakes, as long as encounters are safe for all concerned. J. Frank Dobie would agree. After an encounter with a rattlesnake that he did not kill, he wrote: “…that rusty old rattler suddenly appeared to me as something natural, native, and honest belonging to the land that I belonged to — a fellow creature that, after all, I would not want to see exterminated” (Rattlesnakes, p.61).

Knowing a little more about rattlesnakes, maybe seeing one while camping or while working a ranch could be a source of joy or wonder. We could watch from a safe distance and admire a creature very different from us, yet a fellow creature nonetheless. 

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