Why Do Snakes Become Aggressive? (5 Reasons)

Your snake just struck at you. Maybe they even landed a bite on you. Regardless, you now have questions racing through your head about why your snake became aggressive toward you and how to avoid being bitten again in the future.

It’s not a fun experience, after all, and nobody wants it repeated. Most importantly this experience might lead you to negatively interpret any movement or head turn as your snake winds up to strike. But the truth is that the motives behind a bite can be distilled down into a fairly straightforward list:

Snakes bite for many different reasons, including hunger, shedding, injury or illness, fear, or to protect eggs. Although mistaken for aggression, their behavior is based in survival, not hostility. By learning your snake’s body language, you can help avoid situations that lead to a bite. 

In this article we will unpack the list of reasons that explain why your snake is trying to strike at you and if these reasons are driven by aggression, fear, or another emotion. We’ll also touch on some snake body language to familiarize yourself with to avoid being bitten. 

Why Is My Snake Suddenly Aggressive?

So, let’s take a look at the possible reasons your snake is suddenly aggressive or about to strike you!

Reason 1: Your Snake Is Hungry

Sometimes it really is as simple as hunger. On a creature’s hierarchy of needs (humans included), food is a basic survival need that has to be met before more complex social or emotional needs are considered. For this reason, a pet snake becomes very single-minded in its hunt for food. 

If your snake is hungry, they may strike at an outstretched hand as a predatory response to the movement or the heat signature that your hand is creating, more so if you have recently handled a prey item of theirs and now have that scent on your hands.

No, this doesn’t mean that your snake views you as their prey, but it does mean that hungry snakes are in a food-motivated headspace and may mistake that flash of movement or heat as prey. The old saying “To a hammer, everything looks like a nail” applies here: To a hungry snake, everything warm and moving looks like food. 

Another important point of body language that may help you determine if your snake is hungry is that their attention will seem focused. They may track your movement if they have learned to associate your presence with food. They may also flick their tongue more frequently than they would if they were exploring their environment. 

Reason 2: Your Snake Is Startled Or Afraid

A snake’s lack of limbs and style of locomotion leaves them vulnerable. When you move through life constantly on the ground, threats come from one direction: above!

Snakes have no claws or protective horns or a hard shell on their back, so their teeth are their only means of fending off unwanted attention from would-be predators or an unexpected grab from a human.

This defensive behavior is often mislabeled as “aggressive”, but the truth is that snakes are not going to go out of their way to bite you for the sake of aggression. In the realm of reptile self-defense, they would much rather run or hide. Biting is a last resort.

Defensive snakes will respond in a number of ways to you reaching into their enclosure, including tucking their head back towards their body, freezing/sitting completely still (especially if a hide they were in is suddenly lifted off from on top of them), or slithering quickly away from you. In any of these cases, your snake is viewing this advance as a predatory behavior and may bite if it feels cornered. 

Over time, socializing your snake and getting it used to being held will help reduce the instances in which your snake might perceive you reaching into their tank as a threat to their safety. Getting your snake used to handling and continuing to consistently handle your snake throughout their life is essential to help manage their overall stress levels. 

If you notice that your snake is defensively striking any time you reach into their tank, here are a couple of suggestions to help mitigate that behavior:

First, make sure your snake has enough hides so that it does not feel exposed. You can also consider changing from a tank with top access to a tank that has doors that open from the front. Especially if your snake is not usually a nippy species, the biting could be because their enclosure setup is not adequate.

For jumpier snakes, having a terrarium that opens from the front instead of the top can help give you access to your snake and their enclosure in a way that is not as threatening to them.

Front-opening terrariums also give your snake the option to poke its head and upper body out of its enclosure a little, at which point you can offer supporting hands from underneath them, instead of above. This makes all the difference if being able to handle your snake regularly is important to you as a reptile owner.

Reason 3: Your Snake Is Preparing To Shed

Being in shed mode is a dangerous time for snakes, both domestic and wild. The cap-like scales that cover their eyes (like goggles) become milky and translucent, obscuring their vision.

Snakes preparing to shed or in shed will lay low, preferring to hide and conserve their energy until they have completed their shed. Some snakes will even stop eating during this period of time. 

When your snake is tucked away in its hide with milky eyes, your chances of getting a defensive nip are far higher than they would otherwise be because your snake can’t clearly see you.

It’s a good general rule to not handle your snake more than necessary right before or during the shedding process. 

Reason 4: Your Snake Needs To See A Veterinarian

An injured or ill reptile’s behavior can shift considerably from their norm. Whether lethargic, skittish, or outright defensive, a change in your snake’s regular demeanor should be taken seriously.

If you have ruled out hunger or being startled, and you know that your snake is socialized, then a shift in behavior wherein your snake is striking more than usual might be caused by something health-related.

Unlike pet dogs, who may seek out the comfort and attention of their owners when feeling unwell, snakes are more likely to downplay or hide the fact that they don’t feel well. This is driven by their survival instinct, which compels them to not reveal weaknesses to potential predators.

Because of this, even a seemingly minor indication that something is wrong should be taken seriously and your snake should be brought to an exotic veterinarian before symptoms worsen. 

Reason 5: Your Snake Is Protecting Its Eggs

Snakes are fearsome mothers. If your pet has laid a clutch of eggs, a bite is a guarantee for anyone that comes too close. Knowing this can spare you and your female snake a lot of stress. 

If you are experienced at breeding snakes and are attempting to get eggs away from a female, you are already well aware of how likely it is to sustain a bite from this type of interaction.

If, on the other hand, your female producing a clutch of eggs has come as a total surprise to you, make sure to change your practices about housing males and females together, then reach out to your local exotic veterinarian for advice on if you should separate the eggs from the female and, if so, how they recommend doing so in a way that is safe for you and your snake.

How Can You Tell If A Snake Is About to Strike?

A snake’s body language will almost always communicate a snake’s intention to strike. By knowing what body language to look for, you can determine when your snake is likely to strike and avoid the situation before a bite ever occurs. 

Even though snakes do not have limbs, they still have ‘posture’ and other cues that clue us into how they are feeling at any given moment. A snake that is preparing to strike will do any combination of the following:

1. Flicking Or Rattling Their Tail

This is not just a rattlesnake or pit viper behavior. Snake species like rat snakes, king snakes, and gopher snakes are known to rapidly twitch or shake their tails to communicate agitation.

This is known as ‘Batesian mimicry‘, a type of mimicry where a harmless or edible species of plant or animal mimics a dangerous or inedible species through behavior or morphology to protect itself from predation.

In the first few seconds of the below video, this wild snake is rattling its tail against dry leaves to intimidate the person filming it. If you continue to watch the video, you will notice that at the earliest opportunity, the snake then turns and begins to retreat, keeping a wary eye on the person filming as it slithers away:

If you have a species of pet snake that exhibits this type of Batesian mimicry, it’s a reliable tell for when you are at a greater risk of being bitten.

2. An S-Curved Neck And Tense Body

Spotting tension in the neck is key snake body language for any reptile owner. This posture can be extreme or it can be more subtle, with less of the body involved and not lifted so high up. 

The S-curve posture serves a practical purpose of acting like a ‘coiled spring‘, providing a snake all the potential energy it needs in its muscles (and the reach it needs) to make sure it lands a bite on its intended target.

By drawing itself back, an offending hand or predator truly can’t dodge a strike quickly enough once they enter that snake’s ‘strike zone’

In some cases, strikes are bluffs and either do not connect with a bite to skin or (in the case of venomous snakes) may be a dry bite without venom expended. But it is always important to treat a snake poised to strike as if it can and will follow through with a bite (and with venom, if it is a venomous species). 

Here is an example of a snake displaying an S-curve as part of a defensive posture. Notice that along with the S-curve, the rat snake in this video is also shaking the tip of its tail, tracks the movement of its owner’s hand, and holds its mouth open at one point, all indications of an impending strike.

Note, the woman depicted in this video is an educator and is not doing anything to intentionally upset the snake in this video. This rat snake is in the process of being socialized to get more comfortable with being handled:

When S-Curves Are Not A Concern

Although snakes do take on an S-curve posture when preparing to strike, there are plenty of times a snake might be holding its body in a way that makes its head and neck form an ‘S’.

An exploring snake or a curious snake’s body may make this curve, but in no way does this indicate your snake is about to bite you. To put it plainly, a snake holding itself in any position aside from a straight line is going to form some kind of curve. 

The difference in a normal, relaxed S-curve versus an S-curve indicating a snake is about to strike is the tension in the rest of your snake’s body. If the rest of your snake’s body is tense and they are forming this curve, then they may be preparing to strike.

So, if you’re holding your snake and the rest of its body is relaxed but its head and neck are moving around, it is more likely that your snake is just exploring.

3. Head Drawn Back Close To The Body

This wild bull snake is a good example of what it looks like when a snake is drawing itself back in a defensive posture. Keeping its head back and towards the center mass of its body, this puts them in a better position to execute a strike with proper reach and force, like winding back for a punch.

Notice how it is keeping its head off the ground and low.

4. Hissing

Snakes are not ‘chatty’ animals. They do not vocalize for attention or out of pleasure. If your snake is hissing, whether it is once or several times, take it as a clear sign that your snake is feeling defensive.

Hissing is meant to make a snake come across as formidable and sound larger than they actually are to potential predators. So, if your snake is hissing at you, something you are doing is compelling them to treat you as a threat. 

It’s worth pointing out here that snakes squeak if there’s some water stuck in their nose after a soak and may make some strange breathing sounds if they are sick with an upper respiratory infection.

However, these sounds are different than a hiss, which is a steady stream of air in or out of the glottis (an opening in their mouth that connects to their wind pipe). 

5. Irregular Tongue Flicking

This is not a one-size-fits-all behavior in the sense that there are a number of reasons a snake might change the frequency with which it flicks its tongue or the length of time it leaves its tongue out for.

But whatever the cause, snakes will flick their tongues more often or leave their tongues out for longer when they are trying to gather information on a smell (whether that smell is thought to be food, something unfamiliar that they want to identify, or a perceived threat).

If your snake is actively flicking its tongue more frequently than usual while tracking movement, you may be observing the behavior of a hungry snake. If your snake is sitting still and flicking out its tongue, leaving it out for much longer than usual, and then bringing it back into their mouth, then your snake is most likely feeling threatened.

These long tongue flicks are your snake’s way of trying to gather as much scent information as possible with each flick before delivering that back to the Jacobson’s organ inside of their mouth (part of their olfactory system that helps them interpret smells). 

Misunderstanding Snake Behavior

While the above behaviors indicate that a snake is about to strike, there are similar-looking behaviors that mean something entirely different. These behaviors are often mistaken for aggression but are not. 

Snakes may curl up for many reasons, not just coiling to strike. A ball python will, as its name suggests, curl up in a tight ball with its head tucked in the middle or hidden under a coil when it is threatened in order to protect itself.

This is not a behavior geared towards preparing to strike, although a frightened snake may promptly decide to bite if not left alone. Instead, this behavior is all about protecting their vulnerable head from a perceived threat.

Snakes will also often rest on their coils when sleeping or basking. This is not the same as a snake drawing its head back towards its coils to wind up for a bite.

You can tell this apart because a relaxed snake will have its chin resting on itself or something near it, versus hovering its head or showing tension in its upper body consistent with that ‘coiled spring’ energy we see in a snake preparing to bite.

Taking this a step further, a snake will raise its head for all sorts of reasons that are not related to biting. Snakes will lift their heads to see where they are going or simply out of curiosity.

A familiar, and adorable, example of this behavior is the ‘periscoping’ head lift seen in ball pythons, where they extend their neck straight up or out and bend their head at a slight angle to look around, much like the periscope of a submarine.

Here is a photo example of this behavior (note that an agitated or defensive snake is not going to extend its neck out like this, as it is a much more vulnerable position than coiling up):


By viewing your snake’s motivations for what they are instead of rubber stamping them as aggressive behaviors, you can come to a greater understanding of your pet’s needs.

Ultimately, your snake is not going to go out of its way to try and bite you. If its basic needs like food and safety are being met, its personal space is being respected, and you put in the time to familiarize your snake with being handled, your overall chances of being bitten are low.

In addition, researching defensive behaviors and body language that are species-specific can help you recognize what is normal versus abnormal for your snake. 

As a final note, spend some time getting to know your snake’s individual personality! Not only will this help you learn your snake’s temperament, but you get the pleasure of learning all their little quirks as well.