Sauromalus obesus obesus
Western chuckwalla

IGUANIDAE

Sauromalus is derived from sauros-, "lizard," and -omalus from the Greek homalus, "flat," in reference to the chuckwalla's flattened body shape. It lacks a mid-dorsal crest, and when compared to its closest relatives (the other iguanas), the low profile is really obvious. The name chuckwalla (or chuckawalla) is derived from the Shoshone word "tcaxxwal" or "caxwal," the form used by the Cahuilla Indians of southeastern California and originally written in Spanish as "chacahuala."

Description

Size: The stout-bodied chuckwalla is the second largest lizard in the United States, next in size only to the gila monster. A male individual can measure up to 18 inches in total length, while the female is somewhat smaller.

Coloration: In adult males, the head, shoulder, and pelvic regions are melanistic, while the mid-body is light beige or tan and occassionally speckled with brown flecks. The tail is off-white. The tail is a lighter. Adult females are brownish in color with a scattering of dark brown and red spots. Young chuckwallas have four or five broad bands across the body, and three or four on the tail. These bands are usually lost in adulthood. Uniformly small scales cover the body, with larger scales protecting the ear openings.

Range and Habitat

The Western chuckwalla's range covers east-central California, southern Nevada, southwestern Utah, western Arizona, and northeastern Baja California. In San Diego County, this lizard is common in the desert foothills and desert mountain areas.

The chuckwalla's prime habitat is boulder covered slopes, at elevations up to 6000 feet, though most often at lower elevations. They sun themselves on prominent rocks during warm weather, and it's not unusual to see several chuckwallas at the same time from a single vantage point.

Natural History

In the wild, chuckwallas are shy, and, if approached, will hide in the cracks and crevices of nearby boulders. If the threat persists, they can wedge themselves tightly in the crevice by inflating their lungs up to three times the normal breathing capacity. This makes it almost impossible for a predator to drag them out.

Western chuckwallas are strictly herbivores in the wild. In captivity, they have been known to eat mealworms. They're particularly fond of yellow flowers, such as those found on the brittle-bush (Encelia farinosa), and, on occasion, will trample this plant in hope of a yellow feast.

Mating occurs between April and July, with a clutch of as many as 16 eggs laid between June and August. The eggs hatch in the late warm season.

Conservation Status

chuckwalla populations appear healthy and stable, benefiting from the rugged nature of its habitat, which discourages human intrusion.