There are lots of interesting and unique traits and characteristics in bearded dragons, which is why bearded dragon keeping is so much fun.
Lots of their movements are due to evolution and others have specific purposes. One thing that you might have caught your bearded dragon doing is opening his mouth.
A bearded dragon with its mouth open looks odd the first time you see it. You might see them in their basking area with their mouths open or see them positioned undercover doing the same.
While a bearded dragon mouth open isn’t a definite sign that something is wrong, it is important to find out why he’s doing it. Importantly, you need to rule out stress and pain.
There are lots of possible reasons why bearded dragons have an open mouth, to find out why your pet is doing it, you’ll need to pay attention and investigate.
To make this easier, we’ve compiled a list of all of the usual reasons why a bearded dragon might keep his mouth open.
Keep reading to find out our nine reasons why bearded dragons open their mouths.
1. Regulating Body Temperature
Unlike humans, bearded dragons (and all lizards) can’t sweat. Humans sweat to cool down and so bearded dragons need to find different ways to cool themselves down and regulate their body temperature.
This is one reason why a bearded dragon opens its mouth. When he does this, it’s called gaping. Gaping allows the extra body heat to escape, thus reducing the beardie’s overall temperature.
A bearded dragon gaping when basking is normal behavior. You might notice this action when he is sitting under the heat lamp, for example.
If, however, you notice this in other places, you need to make sure the tank temperature is not too high and that there is a cool spot for your beardie.
It is most common for a beardie to gape while he is basking, which usually means that he will do this while sitting on a rock under the heat lamp. This happens when the bearded dragon reaches its thermal maximum and its body temperature is at its highest.
Gaping means the bearded dragon can let the excess heat escape to keep him at his ideal temperature. Essentially, gaping protects them from overheating.
If the bearded dragon is gaping in other areas of the tank, you may want to investigate to ensure that there are some cool spots where your dragon can go to cool down.
If you notice your bearded dragon doesn’t go under his basking light very much, it could be a sign that the enclosure is already too warm.
All terrariums need warm areas and cool spots to allow the beardie to warm up and cool down as he needs to maintain their optimal body temperature.
This reason for mouth opening behavior is the most common.
2. Stretching Their Beard
Bearded dragons, as their name suggests, have a beard around their necks. Beard stretching is quite common and is recognized through an open mouth. If you’ve ruled out gaping, the next thing to look for is your bearded dragon beard stretching.
Beard stretching looks like gaping but it is a defensive behavior. To differentiate between gaping and beard stretching, you might notice your bearded dragon turn black or go darker in color.
What’s more, there might be other signs of aggression too.
To show aggression bearded dragons try to appear larger, which is why they have their mouths open.
It is an instinctive behavior when feeling under threat but it can also be down to your bearded dragon exercising his muscles and this would depend on when he’s doing it.
Just like us, if your pet hasn’t used his mouth muscles in a while, he will feel like stretching. If it is just stretching, then he won’t have his mouth open for a long period.
Bearded dragon owners might also see this behavior when the beardie is preparing to shed. This will usually be accompanied by puffing the beard out too.
The reason for this behavior is so that they can stretch and loosen the skin, making it easier to shed.
Even if your beardie isn’t getting ready to shed, stretching his beard is normal and you’ll learn about your beardie’s individual behaviors the more you observe him.
Do Beardies Yawn?
Yes! Like the majority of animals, bearded dragons do yawn. A quick beard stretch isn’t necessarily yawning though, even though it might look like it.
3. Defensive and Aggressive Behavior
As a bearded dragon owner, you’re probably very used to your pet lizard being placid and calm. They typically get on well with their owners and even deal with strangers quite well too.
Sometimes, however, they can feel a little uneasy and this might be demonstrated in aggressive and defensive behavior.
Typically, a bearded dragon appreciates its size in comparison to humans and as a result, bearded dragons sit easy with their owners. However, they have strong instincts and will act accordingly if they feel threatened.
One aggressive response is to open their mouth. The reason for this is that they try to frighten and intimidate you. It’s entirely normal behavior for them in the wild if other creatures cross their path, for example.
If the reason behind the bearded dragon’s open mouth is that the animal feels threatened, it will usually be accompanied by a tall stance, a hiss, a charge, or even a bite.
Bearded dragons open their mouths as a ‘flight or fight’ response. With their mouth wide, they try to appear bigger.
What Causes This Bearded Dragon Behavior?
There are lots of reasons why your lizard might suddenly be on the defensive. Firstly, if there are other pets in the home, a bearded dragon opening his mouth is expected.
After all, he will be frightened that these other pets are predators. If this is an occasional behavior, you don’t need to worry so much.
However, if your bearded dragon has his mouth open every time your other pet enters the room, he is most likely to feel threatened by it.
This isn’t a good sign and it means you should probably keep other pets separate to avoid undue stress.
Keep Other Animals Away from Your Bearded Dragon
This can be harder said than done, depending on your setup. You could move your bearded dragon into a room that other animals won’t go into. A guest room, for example, is a good idea because a larger pet is unlikely to visit there.
It’s not just animals inside the home that you need to be mindful of. Though being next to a window is great for stimulating a bearded dragon’s mind, if there are lots of birds or squirrels outside, your bearded dragon might feel threatened.
If you see your bearded dragon open-mouthed frequently and he is near a window, you could consider moving his enclosure away.
4. Enclosure Location and Position
Since we’ve mentioned windows, this might be another reason why your bearded dragon is opening his mouth – and not just because of the creatures in the outside world.
A reason for open mouth behavior when near a window could be due to other movements outside like clouds or noises when trees rustle, for example.
What’s more, the sun could after the optimal temperature of the enclosure.
If this is the case, you’d notice your bearded dragon not spending much time in his basking area. There should be no direct sunlight in the cage.
5. Feeling Threatened Causes Them to Open Their Mouth
As well as pets and noises, other items can cause a bearded dragon to feel threatened. This might be children’s toys, clothing, small objects, decorations, and ornaments.
If you can figure out what’s causing your pet to be distressed, make sure it’s not in his line of sight.
If the mouth opening occurs when you’re handling your dragon, it could be that his ‘third eye’ has sensed a change in shadows above and he feels under threat.
Make sure you handle him with your hands supporting underneath his body and don’t make sudden movements, especially above his head.
6. Respiratory Infections and Bearded Dragon Mouth Open
A concerning reason for bearded dragon open mouth behavior is if he has a respiratory infection. These are common if the case has high humidity – especially if this is for long periods.
A beardie is not suited to breathing moist air so it’s important to control the tank humidity and keep it below 40%.
A lizard, like a bearded dragon, is not used to being in a humid environment. In the wild, they live in dry, hot places. They’re simply not suited to breathe moist air.
To keep humidity levels in range, make sure their water bowl is located away from the heater. Also, don’t use items that retain moisture like bark. You should also make sure there is adequate ventilation.
Signs of a respiratory infection include, mouths being open (even when they’re not basking) and seeing mucus around or in the mouth.
If you don’t spot the signs of a respiratory infection or it gets worse, you’ll notice the beardie being lethargic and listless.
Like humans, they also have coughs, wheezes, mucus, and noisy breathing. This is why you need to assess any gaping in your beardie to make sure it’s not because of illness. If you suspect your dragon has an infection, take him to the vet to be assessed.
There are a number of things you can do to prevent respiratory infections in bearded dragons:
- Make sure you have a hygrometer to measure the humidity and keep it below 40%.
- Only use a small water bowl and keep it away from the basking area.
- Don’t use bark or moss as they retain moisture.
- Add more ventilation.
- Consider purchasing a dehumidifier for the room if you can’t bring the humidity level down.
7. They’ve Seen Another Bearded Dragon
Another thing that can cause your dragon to feel uneasy is another lizard. You should always have separate tanks if you have more than one dragon, it’s not recommended to house more than one together – even if they’re male and female.
If you’re breeding, only keep them together for the mating season.
By nature, a dragon is a solitary creature and problems will occur when there is more than one in the same tank.
When there are two bearded dragons, these solitary creatures won’t be happy. They will fight for dominance and it’s not pretty.
Bearded dragons are territorial and so they will fight to be the alpha. It will be the most dominant that opens his mouth in order to show he is in charge of certain areas in the enclosure. This will include the basking spot, caves, and hiding spots.
Firstly, the dominant dragon will open their mouth to show it is the bigger and stronger ‘alpha’ dragon.
The other dragon will have a tough time and will feel stressed. Potentially, he will stop eating and won’t be able to bask because of the dominant one.
If you see these behaviors in your lizard enclosure, you should separate them into individual tanks.
You might even have to put the tanks in different rooms because they can still threaten/feel threatened if they can see or hear one another.
8. Keeping Mouth Open in Mating Season
When you keep bearded dragons, you’ll notice their behavior changes at certain points in the year.
Just after brumation, a bearded dragon’s hormones rage and they can become more aggressive. As we’ve seen above, this can cause them to open their mouth.
Sometimes they can’t even handle being handled and will get aggressive with their owners. What’s more, they’ll show more signs of being territorial as you approach the tank.
Of course, these hormones and behaviors are all-natural and will subside when their hormones calm down.
Males that are typically docile and placid can become really aggressive during mating and so the mouth opening behavior will be more likely.
If you are breeding bearded dragons, you should keep them together for around one week before separating them to give them a break.
9. Your Beardie Has Just Eaten
Our final reason why a bearded dragon might have his mouth open is just after he’s eaten.
If your beardie has eaten a large meal or has eaten too quickly, he might feel a little uncomfortable – just like we do when we’ve done the same.
If this is the case, your bearded dragon might keep his mouth open to try to get rid of any gas and help him digest his meal.
Final Thoughts: Bearded Dragon Open Mouth Behavior – Should You Worry About Your Beardie?
Most of the time, when bearded dragons have their mouth open, there is nothing to worry about.
This instinctive behavior is usually natural in a beardie and not a cause for concern.
However, it could be a sign that your bearded dragon is feeling threatened or upset.
The worst-case scenario would be that it is caused by a respiratory infection and the bearded dragon is struggling to breathe.
It’s much more likely, though, that your beardie is simply regulating his body temperature through gaping and putting his mouth open to vent heat from the body.
If your bearded dragon mouth open behavior only occurs during basking, he’ll simply be gaping and helping regulate his body temperature.
See a Vet if You’re Unsure
If ever you’re unsure whether this beardie behavior is gaping or something else, you should take your bearded dragon to see a vet to be checked over.
A vet will be able to diagnose a respiratory infection if one is present.
The more you get to know your bearded dragon, the easier you’ll find it to figure out what is causing him to open his mouth.