Harmless · Native to the United States

Common chuckwalla

Sauromalus ater Duméril, 1856

Also called chuckwalla; formerly Sauromalus obesus
Data updated October 2026

Adult male common chuckwalla basking on a boulder, with a black head and forelimbs and a reddish back
Fig. 1 — Adult male basking on rock, with the black head and forelimbs typical of males.
Female common chuckwalla with gray and yellow crossbands on a rock
Fig. 2 — Females and young keep gray and yellow crossbands.

At a glance

A big, flat, plant-eating lizard of desert boulder fields and lava flows. After the Gila monster it is the largest lizard native to the US. When threatened it dives into a crack and puffs itself up with air so it cannot be pulled out.

01

Identification

The chuckwalla is a large, heavy lizard with a flattened body, a rounded belly and loose folds of skin on the neck and sides. The tail is thick at the base with a blunt tip. Adult males have a black head, chest and forelimbs, and the body can be black, red, orange, gray or yellowish, often with pale flecks, while the tail is usually light gray or cream. Females and young are crossbanded in gray and yellow or dark and light. Color varies a lot from place to place and often matches the local rock.

  1. 01Flat, bulky body. Wide and heavy, with baggy skin folds along the neck and sides.
  2. 02Black-fronted males. Black head and forelimbs with a red, gray or yellow body and pale tail.
  3. 03Blunt tail. A thick, wide-based tail with a blunt tip.

Commonly confused with

The desert iguana is slimmer and paler with a crest down the back. The Gila monster has beaded pink-and-black or orange-and-black skin.

02

Size

01 ft2 ft3 ft4 ft Typical adult · about 15 in (38 cm)

The body measures 5 to 9 inches (12.7–22.8 cm) from snout to vent. Adults commonly reach about 15 to 16 inches (38–40 cm) including the tail, and the largest grow to about 20 inches. Males are generally bulkier than females.

03

Range & habitat

Desert hillside of jumbled boulders and rock outcrops
Fig. 3 — Chuckwallas are strictly rock dwellers, living among boulders, outcrops and lava flows.

Common chuckwallas live in southeastern California, southern Nevada, southwestern Utah and western Arizona, and south into Baja California and Sonora, Mexico. In California they occur through the Mojave and Colorado deserts, north to the Owens Valley and the White Mountains, where the first Mono County record was found in 2016.

They are rock specialists of the Mojave, Sonoran and southern Great Basin deserts, found on rocky hillsides, boulder piles, large outcrops and lava flows, usually within creosote-bush country, from sea level to about 6,000 feet. Now and then they turn up in odd spots such as riprap and stacks of railroad ties.

04

Diet & predators

Chuckwallas are plant eaters. They feed on the leaves, buds, flowers and fruit of annual plants and shrubs, especially creosote bush, and eat insects only now and then, mostly when plants are scarce. A long gut with helpful microbes lets them digest tough plant matter, and they store water in lymph sacs under the side skin folds and in the tail.

Feeds on

  • Creosote leaves, buds and flowers
  • Annual wildflowers and their leaves
  • Fruit of desert shrubs
  • Occasional insects

Preyed on by

  • Hawks and other birds of prey
  • Coyotes and foxes
  • Snakes (young chuckwallas)
  • People, historically, for food
Creosote bush with small yellow flowers
Food — creosote bush.
Red-tailed hawk perched on a post
Predator — hawks.

05

Behavior & seasons

Chuckwallas are active by day. They come out early to bask on large rocks, then forage, and pull back into crevices during extreme heat. When threatened, a chuckwalla runs into a crack, gulps air to inflate its body and uses its claws and rough skin to wedge itself in tightly, so a predator cannot drag it out. It does not drop its tail to escape.

They spend winter deep in rock crevices and come out from mid-to-late February onward, though they may appear on warm winter days. When food is plentiful, large males hold territories and smaller males fall into a size-based pecking order; males threaten with push-ups, head-bobs and open-mouth displays and fight only as a last resort.

06

Reproduction

Mating happens from about April to June. Females lay 5 to 16 eggs, about 6 on average, in a hidden nest between June and August, then leave. Not every female breeds each year; some lay only every two or three years, and in lean, dry years few may breed at all. Hatchlings emerge in late September and are on their own. Chuckwallas can live 10 to 15 years in the wild.

07

Conservation

The common chuckwalla has no listing under the US Endangered Species Act or the California Endangered Species Act, though it appears on California’s Special Animals List. It remains widespread in rocky desert habitat. Collecting rules vary by state, so check local regulations before handling or keeping one. See which reptiles are listed

Keep reading

Sources

Data updated October 2026 · How we build these pages