Part of the appeal of bearded dragons is the vast array of behaviors they display. Many of these behaviors, like mouth gaping, head bobbing and arm waving, are easy for keepers to interpret and understand. However, many bearded dragons will exhibit digging behavior, which can cause their owners concern.
When you see a bearded dragon digging, your first thought should be that the lizard may be gravid -- full of eggs -- and looking for a place to lay them. Eggs are usually visible through the female’s abdomen, especially by the time they start digging. Note that females may store sperm and lay eggs without being with a male, though this is not terribly common. Wild bearded dragons dig small burrows at the base of a rock or plant to deposit their eggs in. Gravid bearded dragons -- especially first-time moms -- may appear nervous or hyperactive as parturition approaches. If you believe your dragon is trying to lay eggs, place her in a plastic container with damp -- not wet -- sand and leave her alone. If it takes more than 24 hours for her to deposit eggs, place her back in her habitat for a few hours to bask and drink water.
Wild bearded dragons engage in a behavior termed brumation to survive the inhospitable winter temperatures of the Australian desert. Brumation is roughly the ectothermic equivalent of hibernation, and to do so, bearded dragons dig or find a burrow to spend the winter inside. Once inside, the dragon won’t eat or drink, and her metabolic rate will drop dramatically. Bearded dragons don’t need to brumate, but as winter approaches, cage temperatures may decrease slightly as does the ambient light reaching the cage. When you see this behavior you can increase the temperature slightly and make the cage brighter to break the lizard’s urge, or you can allow it to brumate for a month or two. If you choose to let the lizard brumate, first be sure that his digestive system is empty by keeping it warm for a week without feeding him. Then turn off the cage lights entirely, or set them to come on for only a few hours per day. Provide some newspaper sheets or towels in the cage for the lizard to crawl under, and say good night. The lizard may choose to be active occasionally, but for the most part, he will sleep for 30 to 60 days before becoming active again.
Bearded dragons don’t understand glass; they never come into contact with a clear, impenetrable substance in the wild. Accordingly, you may see your bearded dragon digging at the glass occasionally. Sometimes, this is because the bearded is just trying to figure it out, but most commonly, bearded dragons dig at the glass because they see something outside the cage they want. This could be an attractive female bearded that he wants to mate with, a smaller male he wants to chase away or -- most commonly -- the lizard sees a bug crawling around and wants to eat it. As an occasional behavior, this is no cause for concern, but if your bearded does this frequently, investigate the cause and try to rectify it by moving one of the lizards.
Many times, when a bearded dragon digs she is just trying to get comfortable. Beardeds may clear the substrate away from a rock so they can bask. Additionally, it appears that some bearded dragons simply prefer to rest on the glass or plastic cage floor. In any event, this type of digging is not cause for concern.