Why Do Rattlesnakes Have a Rattle on Their Tails?


Written by Brandi Allred

Updated: July 13, 2023

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It’s a true fact that all rattlesnakes have a rattle on their tail. But not all rattlesnake rattles are equal. 

Rattlesnakes are members of the pit viper family, so named for the heat-sensing pits on their faces. Some of the most common species include the timber rattlesnake, prairie rattlesnake, Mojave rattlesnake, eastern diamondback, and western diamondback. All species are vulnerable to predation by kingsnakes, roadrunners, coyotes, feral pigs, and birds of prey. 

Like other snakes, rattlesnakes prey mostly on small creatures like mice, rats, and rabbits. In fact, if we didn’t have rattlesnakes, these small grass-eaters would quickly denude all the plants in their habitat, leaving nothing left for other herbivores like deer and antelope. Rattlesnakes, and the rattles on their tails, may be scary — but they’re much more dangerous to small mammals than they are to humans.

Here, we’ll learn more about rattlesnake rattles, why they have them, how they use them, and what they’re made of. Then, we’ll go over the steps you should take if a rattler rattles at you and go in-depth on why rattlesnakes are important to the environment.

Do All Rattlesnakes Have Rattles?

Largest Rattlesnake

All rattlesnakes have rattles — or the ability to grow a rattle.

Of nearly 60 species, all of them have rattles. But rattlesnakes aren’t born with a ready-made rattle. Baby rattlesnakes hatch from eggs while still inside their mother’s womb. Female rattlesnakes actually incubate the eggs inside their bodies, then give birth to live young. When the snakelings are born, they have only one rattle segment, not enough to make any noise with. 

Within one week of life, the baby rattlers shed their skin and gain a rattle segment. But it’s not until they have at least three segments that they can produce the sound that makes them so famous. As rattlesnakes grow, they gain a rattle segment every time they shed their skin. But the length of the rattle can’t be used to determine age because they shed several times per year, and rattle segments break off frequently.

What Are Rattles Made Of?

Rattlesnake rattles aren’t made of bone. Instead, they’re made out of keratin, the same substance human fingernails and hair are made of. Each rattle segment fits inside of the next one, but the fit isn’t perfect. They’re only loosely fitted to the one behind and in front of it, so when the rattlesnake shakes its tail, the segments vibrate against one another, producing the characteristic rattle sound.

Why Do Rattlesnakes Rattle?

Aruba rattlesnake

Rattlesnakes rattle to warn potential aggressors off.

Rattlesnakes aren’t the only snakes in the world that rattle their tails, but they’re the only snakes with an actual rattle. Yet, why do they do it? Well, they don’t use their rattles to hunt — rattlesnakes depend on the element of surprise to stalk and kill prey like mice and rabbits.

Rather, they use their loud rattles to warn away threats like humans, cows, coyotes, kingsnakes, and roadrunners. The rattle is the rattlesnake’s way of saying, “Hey, I have a venomous bite, and if you get too close to me, I’ll be forced to use it.”

Scientists believe their rattles evolved as a direct response to bison — these lumbering giants didn’t see or hear the snakes before they had rattles. It was a defensive evolution to keep from being stepped on.

Rattlers only rattle as a last resort before biting, but the ability to rattle means that more rattling snakes survive than non-rattling snakes, which is exactly why the rattlesnake has a rattle.

Occasionally, hikers run into rattlesnakes that don’t rattle at all. This can happen for a number of reasons — the person may not be close enough to warrant a rattle, or the rattler may still be relying on their ability to stay hidden. Whether you see a rattlesnake or hear it, there are a few things you should do to avoid a bite.

What to Do if a Rattlesnake Rattles at You

Aruba rattlesnake

It’s best to move away from the sound of a rattle if you hear one.

So you’re walking along a forest path or maybe taking in the smell of sagebrush in the desert, and you hear the rattle of a rattlesnake. What do you do? 

Your first step is to freeze, don’t make any sudden movements. Listen to the sound, and, without moving, try to figure out where the snake is. Once you know where it is, slowly move away from the sound. The rattlesnake will likely keep rattling at you until you’re a good distance away. Don’t try to find the snake—most people who hear rattlesnakes never actually see them, and that’s a good thing.

If you do see the rattlesnake, take the same steps. Don’t approach it, and don’t attempt to kill it. Statistically, you’re much more likely to sustain a bite if you attack the rattlesnake than if you just leave it alone. Remember, rattlesnakes don’t want to bite you; that’s why they rattle.

Can Rattlesnakes Live Without Their Rattle?

Rattlesnakes may lose their rattles in several different ways, including injury from a predator or accidental crushing. Rattleless rattlesnakes are extremely uncommon, and most don’t live long. Without a way to let predators know that they’re dangerous, they soon fall victim to predators like kingsnakes and roadrunners.

Occasionally, people attempt to kill rattlers for their rattles. This is a bad idea for several reasons, the first of which is the danger of getting bitten. Additionally, some hikers report that rattlesnakes seem to be rattling less in recent decades, though no scientific studies have ever shown this to be true. 

Why Rattlesnakes Matter

Rattlesnakes and their rattles may be terrifying, but they’re actually important parts of the environment. They keep rodent populations down. Without them, things like mice and rabbits would soon eat themselves out of house and home. Killing rattlesnakes for sport or out of fear not only disrupts the ecology of the region but also puts other animals at risk of starvation. 

If small mammals eat all the food, then there’s none left for larger animals, like elk and deer. With no food, these animals cannot survive in the environment. So, rattlesnakes may seem scary, but they’re actually vital to keeping the natural world in balance.

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About the Author

Brandi is a professional writer by day and a fiction writer by night. Her nonfiction work focuses on animals, nature, and conservation. She holds degrees in English and Anthropology, and spends her free time writing horror, scifi, and fantasy stories.

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