We associate tail-rattling with rattlesnakes, but several types of snakes can create a buzzing sound with their tails. There is disagreement over how this behavior has evolved, but most scientists agree that other snakes will vibrate their tails to scare off predators (as a form of Batesian mimicry).
Venomous pit vipers (cottonmouths, copperheads, terciopelos, cantils, and bushmasters) will rattle their tails when scared or threatened. Also, non-venomous rat snakes, corn snakes, kingsnakes, and gopher snakes will buzz their tails against the ground to frighten off predators.
The mimicry of colubrid snakes will often be short-lived as they lack the muscle strength to shake their tail for more than a few minutes. We’ll explain which snakes rattle their tails and how snakes that lack a rattle can vibrate their tails make a rattling sound.
Snakes that Rattle Tails
Rattlesnakes (Crotalus) can vibrate their tails faster than any other snakes, but they’re not the only species to engage in this type of behavior.
According to The American Naturalist, tail-shaking occurs in almost all 200 species of the viper (Viperidae) family. Tail-vibration is seen in other venomous pit vipers such as copperheads (Agkistrodon contortrix), cottonmouths (Agkistrodon piscivorous), and bushmasters (Lachesis).
However, it’s not just venomous snakes that shake their tails. A significant proportion of colubrid (Colubridae) snakes rattle their tails, too. This includes:
- Rat Snakes (Pantherophis obsoletus)
- King Snakes (Lampropeltis)
- Gopher Snakes (Pituophis catenifer)
- Corn Snakes (Pantherophis guttatus)
New snake handlers are often surprised to see their non-venomous snake behaving in this way because tail-rattling is often only associated with the much-feared rattlesnake.
But non-venomous snakes shake their tails in a different way to rattlesnakes. Whereas rattlesnakes can shake their tails for up to 3 hours at a time, most colubrid snakes would struggle to maintain this behavior for more than a few minutes at a time.
What Makes the Rattling Sound?
According to NewScientist, it’s likely that ancestral snakes (from millions of years ago) shook their tails to scare off predators.
However, until the rattlesnake evolved, tail-shaking was a silent activity. As a result of evolution, rattlesnakes developed a specialized tail that adds sound to this pre-existing behavior.
When colubrid snakes rattle their tails horizontally, they can generate a buzzing sound by shaking their tail against the floor or another surface. However, rattlesnakes generate the buzzing sound independently because they rattle their tails vertically.
The snake’s “rattle” is a strip of hollow, loosely-overlapping keratin scales. When the tail vibrates at high speeds (90 vibrations a second), this creates the characteristic buzzing sound.
Each time a rattlesnake sheds its skin, a new scale is added to the rattle. You can estimate the age of a rattlesnake by looking at the length of its tail. The older the snake, the louder and faster its rattle.
What Does It Mean When a Snake Shakes Its Tail?
- The Rattle is a Warning – Studies have shown that predators are wary of a rattling snake and will avoid snakes that have the fastest and loudest rattles. A vibrating tail is threatening because it signals that the snake is ready to strike.
- The Rattle Is a Defense Mechanism – Venomous snakes use their venom to kill prey, but they’re less likely to use it on a predator. If they feel threatened, they’ll want to scare off the threat, but they’ll avoid biting a predator where possible. If a rattlesnake vibrates its tail to scare off threats, it doesn’t need to waste precious venom or engage in a dangerous confrontation.
- The Rattle Provides a Distraction – Some scientists believe that snakes rattle their tails to distract attention away from their faces. Tails are less vulnerable to harm than faces, so this behavior may help the snake to feel less exposed.
Tail-rattling is mostly a defensive behavior that warns predators to back off.
Do Non-Venomous Snakes Mimic Rattlesnakes?
Tail-rattling is common in venomous species, but we often forget that non-venomous snakes shake their tails, too. Some scientists argue that this is an example of Batesian mimicry.
In other words, non-venomous snakes may mimic the behavior of venomous snakes to appear stronger in front of predators. If rattling is indeed a “warning signal,” this could explain why other (less dangerous) snakes seem to mimic this behavior.
But is this theory that convincing? It doesn’t explain why some Old World non-venomous snakes rattle their tails. For example, Old World species such as the Rat snake couldn’t have learned this behavior from rattlesnakes because rattlesnakes are a New World species.
Ancestral snakes may have been (silently) rattling their tails long before rattlesnakes developed a noisy rattle. Whether they’re mimicking the rattlesnake, or merely exhibiting ancestral behavior, tail-shaking in docile species is still, in all likelihood, a defense mechanism to ward off predators.
Caudal Luring vs. Tail Shaking in Snakes
Although tail-rattling is a defensive behavior, elevating/twitching the tail can sometimes be predatory behavior.
In the wild, some snakes elevate and wag their tails to mimic a small worm or insect. Once the prey has been lured in, the snake will quickly pounce. Vipers (such as rattlesnakes) are renowned for catching prey in this manner.
Caudal luring shouldn’t be confused with tail-rattling because Caudal luring is predatory whereas tail-rattling is defensive.
Some scientists believe that Caudal luring pre-existed tail-rattling and that the shape of the rattle (loosely connected keratin rings) initially evolved to enhance Caudal luring. Indeed, the keratin rings of the rattlesnake’s rattle do look very similar to the heads of small insects.
Over time, the rattlesnake’s rattle has developed an additional function (i.e., warning predators off). This is only a theory, and some people dispute whether Caudal luring came before tail-rattling.
What to Do If Your Snake Keeps Shaking Its Tail
Corn, rat, king, and gopher snakes shake their tails – both in the wild and in captivity. Given that tail-rattling is a sign of fear or unease, you may be concerned to see this behavior in your pet snake.
Considering your snake’s behavior in context is essential. If your snake’s tail is vibrating in the following scenarios, there’s probably nothing to worry about:
- Your snake’s tail vibrates when you pick it up, but it calms down after a minute of handling.
- Your snake is a juvenile (i.e., less than a year old). Corn snakes rattle their tails as juveniles.
- Your snake is settling into a new home – give him/her at least a couple of weeks to adjust.
- The snake is feeding – snakes are vulnerable when they’re feeding, so it’s common to see their tails vibrating. Don’t make any sudden movements or disturb your snake when it is feeding.
However, if your snake vibrates his/her tail very often, this could suggest they are overly stressed. Similarly, if it vibrates its tail when picked up but doesn’t seem to calm down after several minutes of being handled, you might need to make some adjustments.
To ensure your snake is as relaxed as possible, consider the following:
- Has your snake got enough hide boxes? It needs 2-3 hide boxes, at different temperature gradients, so it doesn’t feel overly exposed.
- Are there other pets (dogs, cats, etc.) in the same room as your snake?
- Has your snake got enough space? The perimeter of the enclosure should be double the length of your snake.
- Are you picking up your snake too quickly? It’s good to handle your snake confidently but let it know you’re about to pick it up. When you open the terrarium, spend a few minutes checking over the substrate or changing the water bowl so your snake can recognize your smell.
- Are you co-habiting your snakes? Most snakes aren’t suitable for co-habiting as they tend to fight over resources and may resort to cannibalism. If you’re keeping two snakes in one cage and one is regularly rattling its tail, this is a clear sign of hostility.
- Are you handling your snake too often? If your snake is comfortable in its hide box and you go to disturb it, it may vibrate its tail in annoyance. Try handling your snake at times you know it is going to be active, and do not handle it for 48 hours after feeding.
Tail-rattling is a natural behavioral response to stress. Since it’s impossible to eliminate all stress, you’re bound to see some tail-shaking if you keep a corn, gopher, king, or rat snake. These species adapt well to being handled so you should see this behavior reduce over time.