Sauromalus ater, better known as the common chuckwalla, tcaxxwal, caxwal, or northern chuckwalla, is a species of lizard in the family Iguanidae, which is endemic to the Southwestern United States and Northwestern Mexico. It is found in comparative abundance throughout the Sonoran and Mojave Deserts. These diurnal lizards are well adapted to desert conditions; being active at temperatures up to 102 °F (39 °C). However chuckwallas typically brumate during the winter months. Males are seasonally and conditionally territorial; an abundance of resources tends to create a hierarchy based on size, with one large male dominating the area's smaller males. Chuckwallas use a combination of color and physical displays, namely "push ups", head-bobbing, and gaping of the mouth to communicate and defend their territory. Chuckwallas are primarily herbivorous feeding upon flowers, leaves, seeds, fruit, and the occasional insect. When disturbed, the chuckwalla enters crevices between rocks and inflates its lungs using a gular pump. Lung inflation distends its body and wedges the lizard tightly in place, to keep it out of reach from predators. Reaching on average 20 inches (50.8 cms) in length and 2lbs (.9kgs) in weight, the common chuckwalla is a large, flat-bodied lizard with a large, rounded belly, and a wide-based, blunt-tipped tail. The coloration of these lizards varies by location and between juveniles and adults, as well as between males and females. In adult males, the head, shoulder, and pelvic regions are black, while the midbody is light tan speckled with brown. Adult females are brownish in color with a scattering of dark red spots. Young chuckwallas have four or five broad bands across their bodies which are lost partially my adult females and completely by adult males. Mating occurs from April to July, with females laying five to 16 eggs between June and August. The eggs hatch in late September. Under ideal conditions a common chuckwalla may live up to 65 years.
