Bearded dragon open mouth behaviour
Open mouth behaviour in Bearded dragons can be quite intimidating and even threatening, but there might be other reasons for this to happen. This behaviour can either be normal, threatening or indicative of environmental problems.
As with most other animals, the mouth’s main function is to take in food and water. It has been constructed to be closed most of the time, but with Bearded dragons there might be various other reasons why their mouths are open. These include thermoregulation and threatening behaviour.
Open mouth basking
It is quite normal to see a Bearded dragon bask with its mouth open. Because Bearded dragons cannot sweat, they need other ways to get rid of excess heat. By opening their mouths, excess heat can escape through their breath and the body is cooled down to a more comfortable temperature.
This behaviour is normal as long as the Bearded dragon spends a lot of time in the basking area. When a Bearded dragon spends most of its time hiding or on the cooler side of the enclosure, it can be indicative of too high environmental temperatures.
Bearded dragons also open their mouths when they feel threatened. By opening the mouth the head looks a little bigger and the readiness of biting is clearly indicated. Open mouth threatening behaviour is commonly seen with scared, injured, irritated or intimidated Bearded dragons. Other signs of threatening behaviour includes the fast form of waving, making hissing sounds, dashing forward and flattening of the body. Some Bearded dragons might even bite! Some of these signs might also be seen as part of territorial behaviour.
Although uncommon, aggressive individuals may appear from time to time in pet Bearded dragons. Regular careful handling might help to reduce this behaviour. When a Bearded dragon is scared, injured, irritated and/or threatened open mouth behaviour should be seen as a warning sign.
Open mouth breathing
A third reason for open mouth behaviour in Bearded dragons is that the environmental temperature is too hot. In this case it is more accurately referred to as open mouth breathing and is more serious and can be life-threatening if not rectified immediately. Also see the Bearded dragon temperatures article for more information.