Chuckwallas are lizards found primarily in arid regions of the southwestern United States and northern Mexico. Some are found on coastal islands. The six species of chuckwallas are all placed within the genus Sauromalus; they are part of the iguanid family, Iguanidae.
The genus Sauromalus has a wide distribution in biomes of the Sonoran and Mojave Deserts. The common chuckwalla (S. ater) is the species with the greatest range, found from southern California east to southern Nevada and Utah and western Arizona, and south to Baja California and northwestern Mexico. The peninsular chuckwalla (S. australis) is found on the eastern portion of the southern half of the Baja California Peninsula.
The other species are island-dwelling, so have much more restricted distributions. The Angel Island chuckwalla (S. hispidus) is found on Isla Ángel de la Guarda and surrounding islands off the coast of the Baja California Peninsula. Two rare and endangered species are the Montserrat chuckwalla (S. slevini) found on Islas Carmen, Coronados, and Montserrat in the southern Gulf of California and the San Esteban chuckwalla or painted chuckwalla (S. varius) found on San Esteban Island, Lobos, and Pelicanos.
Chuckwallas prefer lava flows and rocky areas typically vegetated by creosote bush and other such drought-tolerant scrub. The lizards may be found at elevations up to 4,500 ft (1,370 m).
Primarily herbivorous, chuckwallas feed on leaves, fruit, and flowers of annuals and perennial plants; insects represent a supplementary prey. The lizards are said to prefer yellow flowers, such as those of the brittlebush (Encelia farinosa).