The answer to this question varies widely and depends on many factors, so lets first look at a few things that will increase their lifespan and reduce stress and illness.
- Diet: A well balanced diet will promote health and increase lifespan and reduce risk of disease.
- Environment: Incorrect heating, lighting and substrate will drastically cut short their potential.
- Kept in captivity: Depending on the conditions but there are no predators or few health risks in a vivarium.
- No breeding: Breeding can drastically reduce the females lifespan
- Separation/ isolation: No territorial disputes, bullying or fights to risk injury or death, especially between young dragons and males in particular.
- Sex: Males will generally out live the females as the females will develop eggs (even infertile) which can lead to problems.
- Size of the species: Generally the larger species will live for longer than the smaller.
- Space: More space, means more room to grow and move around to exercise.
Bearded Dragons are generally very hardy and you would expect a Bearded Dragon such as the Pogona Vitticeps, the most common pet lizard, to live for an average of 5-8 years where you’re not really paying much attention to their health and just doing the basics – the same can be said for their life expectancy in the wild, although this varies enormously. But if the above points are taken into consideration then they can easily live past 10 years of age in captivity and they have been known to frequently live up to 14-16 years age with a couple of poorly documented cases even reaching 19 and 21 years old but there weren’t any very credible sources to back up these two exceptions.
A Rankins/ Lawsons Dragon being smaller, for example, will live for slightly less but if kept in better conditions will certainly out live a larger dragon kept in a neglectful environment. It’s very much the same for any animal or human, poor care and environment means an exponentially increased risk of premature death even if you have favourable genetics.
So you can see that keeping reptiles is no short term responsibility, treat them correctly and you can expect them to live longer than your dogs, cats, rabbits etc…