DESCRIPTION: A large (up to 229 mm or 9″ from snout to vent) flat and wide lizard with loose folds of skin on the neck and sides of the body. The head, shoulders, and limbs of males are black. Large males have pale gray to cream colored tails. Males on South Mountain in Phoenix have bright “carrot orange” tails. Across most of its range in Arizona large males have orange-red torsos. Large males from Glen Canyon in north central Arizona have pale ash gray torsos. Males from south-central Arizona (south of Phoenix) have black torsos. Females are gray-brown with faint mottling or crossbars and often have faint gray bands on the tail. In far northwestern Arizona adults of both sexes are banded. Young are pale gray with distinct black crossbands on the body and tail. The head is flattened and broad. The tail is blunt on the end and broad at the base. The small, granular body scales of this lizard distinguish it from the Gila Monster which has large bead-like scales.

DISTRIBUTION: This lizard is found across southwestern Arizona, along the states western border, and up through the Grand Canyon into Glen Canyon. It is found at elevations ranging from near sea level along the Colorado River to about 6,000′.

HABITAT: Most of this lizard’s range in Arizona is within the Sonoran and Mohave Desertscrub communities. Populations in the upper Grand Canyon and Glen Canyon are within Great Basin Desertscrub. In some areas it enters Interior Chaparral and Semidesert Grassland. This crevice-dweller is found in rocky habitats such as boulder fields, outcroppings on hillsides and slopes, and lava fields.

BEHAVIOR: The Common Chuckwalla is a diurnal rock crevice-dweller. It is often seen basking on boulders, outcroppings, and rock piles. When threatened it retreats into a rock crevice and inflates itself with air until it becomes securely wedged.

DIET: This lizard is primarily herbivorous. It feeds on a variety of annuals and some perennial plants. It also occasionally supplements its diet with insects.