Common chuckwalla
Joshua Tree's largest lizard, a slow plant-eater that wedges into a rock crack and inflates its lungs so nothing can pull it back out.
Common chuckwalla at a glance
Sauromalus ater chuckwalla is CHUCK-wall-uh; Sauromalus ater is sawr-OM-uh-luss AY-ter
- Type
- Reptile · lizard
- Diet
- Herbivore
- Size
- A big chuckwalla can reach 20 inches nose to tail (51 centimeters), about as long as a skateboard, and can weigh close to 2 pounds (0.9 kilograms), about as much as a full water bottle.
- Lifespan
- 10 to 15 years in the wild.
- Conservation
- Least concern (IUCN); NPS lists it locally at Joshua Tree as a species of special concern.
Eats creosote bush flowers, leaves, buds, fruit, occasional insects
It grazes on creosote bush flowers, leaves, and fruit, then climbs onto a warm rock afterward, because it needs that outside heat to digest what it just ate.
Should you worry?
Not a real worry. The chuckwalla has no venom and nothing worth calling a bite, and it would much rather squeeze into a rock crack than confront anyone. The real rule here is about protecting the animal, not the kid: chuckwallas have grown noticeably scarcer at Joshua Tree over the last 40 years, so admire from a distance, never reach into a crevice after one, and never chase one off its basking rock.
A shadow crosses a sunlit boulder at Joshua Tree and something the size of a skateboard flinches, drops off the rock, and disappears, not into the open desert but straight into a crack between two stones. That’s a common chuckwalla, the biggest lizard in the park at up to 20 inches long, ducking into the one hiding spot built for an animal its size.
Once wedged inside, the chuckwalla pumps its throat like a bellows and inflates its lungs, swelling its body until it presses tight against the rock on every side. A coyote or hawk that reaches in after it finds a lizard that has, in effect, turned itself into part of the boulder. Deflating and walking back out only happens once the chuckwalla decides the danger has passed.
The trick has worked for a very long time, but the population hasn’t held steady. Joshua Tree’s own naturalists describe today’s chuckwallas as far scarcer than they were 40 years ago. The rock crack is still there and the chuckwalla still knows how to use it. Look for the swelled shape wedged tight against the stone, and leave the boulder exactly as jammed as you found it.
Did you know?
- When it's cornered, a chuckwalla squeezes into a rock crack and inflates its lungs until its body wedges in tight, a defense strong enough that a predator often cannot pull it back out.
- It stores water in lymph sacs under loose folds of skin on its neck and body, a reserve tank for dry seasons.
- Joshua Tree's chuckwallas are far scarcer today than they were 40 years ago, according to the park's own naturalists.
Common questions
Are chuckwallas dangerous to kids?
No. They have no venom and no bite worth worrying about, and they would much rather hide than confront anyone.
Why does a chuckwalla puff up in a rock crack?
It inflates its lungs to wedge its body tightly against the rock so a predator can't pull it back out.
What does a chuckwalla eat?
Mostly creosote bush flowers, leaves, buds, and fruit, plus the occasional insect.
How big does a chuckwalla get?
Up to about 20 inches long, nose to tail, roughly the length of a skateboard, and close to 2 pounds.