Geographical Range Southwestern United States
Habitat Rocky deserts
Scientific Name Sauromalus obesus obesus
Conservation Status Not listed by IUCN

Chuck-a-what? Maybe you've never heard of the chuckwalla, a large lizard related to the iguana. But in fact, chuckwallas are fairly common and widespread in the southwestern United States and adjacent areas. There are five chuckwalla species, including the common chuckwalla, Sauromalus obesus; this species, in turn, has four different subspecies, including the western chuckwalla.

All chuckwallas have a unique appearance that can be described in, well, less-than-flattering terms: pot-bellied and baggy, with loose folds of skin around the neck and shoulders. They are large (up to 16 or more inches in total length), with half of that length devoted to the tail.

The chuckwalla's body color is generally dark but the shading varies, depending on the subspecies; the western chuckwalla usually has a light-tipped tail. Young chuckwallas have light-colored crossbands; only females retain these bands into adulthood. And if all that color variation wasn't complicated enough, here's another variable: Chuckwallas can change colors in response to environmental conditions.

Western chuckwallas are diurnal, meaning they're active during the day. In the morning, they bask to warm up, then start searching for food. They are primarily vegetarians, eating an array of leaves, buds, flowers and fruits. Once in a while they eat insects.

Western chuckwallas mate in the spring. About two months later, females lay their eggs underground -- between five and 16 eggs at a time. The eggs hatch in the fall.

When they're not breeding, basking or foraging, western chuckwallas spend a lot of time hanging out in rocky crevices. This is where they spend the hottest and coldest parts of each day. And this is where they shelter and become inactive for weeks or months at a time during the summer (a process known as aestivation) and winter (a process known as brumation -- similar to hibernation but with periods of wakefulness).

Besides providing shelter from the elements, rocky crevices provide a convenient place to hide from predators. When threatened, a chuckwalla will race into a crevice, take a deep breath and inflate its body. Good luck trying to pry that lizard loose!

Did You Know?

The name "chuckwalla" derives from the Shoshone tcaxxwal or the Cahuilla caxwal, which the Spaniards transcribed as chacahuala.