The chuckwalla is the 2nd largest lizard in the southwestern U.S. (after the Gila Monster). Body length is generally 5.5" - 8", with a tail of similar length. While basking, chuckwallas spread their body weight (up to 3 lbs.) by pressing against rock, appearing somewhat flatter with a widened girth. Males tend to be slightly larger than females, and are often darker in color as well. Color varies considerably by subspecies (region), but generally includes grey, reddish brown, and/or yellow. Cross banding patterns are found on juveniles and cross bands are often retained into adulthood by females.
GEOGRAPHICAL RANGE AND HABITAT:
Chuckwallas inhabit rocky desert areas in the southwestern U.S. , especially southern Nevada to northwestern Baja, and the desert side of the southern California mountains east to central Arizona. Some also live in drainage areas of the Colorado River in southern Utah and on islands off the coast of Baja. They are found from sea level up to 6000 feet.
The chuckwalla diet is somewhat distinctive among desert lizards in that they are almost completely herbivorous. They eat flowers, buds, leaves,and fruit. Favorite foods include the fruit of the prickly pear cactus and yellow flowers. Infrequently, they will consume insects.
LIFE CYCLE/SOCIAL STRUCTURE:
Male chuckwallas are territorial and will defend their territory against other males. It is believed that breeding occurs in early April and May. Eggs (5-16) are laid in rocky crevices by August and the young generally hatch out in late September. Chuckwallas do hibernate in the cold months of the year and emerge from their dens around late February.
The loose folds of skin on Chuckwallas (at neck and sides) enable them to climb into a small crevice on a rock face, gulp air to fill their lungs to full capacity and distend their bodies to nearly twice normal girth, so that a predator cannot extricate them. Chuckwallas can modulate their color (somewhat) to better absorb light/heat to regulate their temperature. As diurnal lizards, they are considered one of the"hottest" lizards because they will bask until their bodies reach 100 to 105 degrees. Like many lizards, chuckwallas are capable of autotomy, so they can break off and re-grow a tail, if necessary, to evade predation. Chuckwallas' teeth grow in grooves inside their mouth. If they lose one, they will re grow one to replace it.
While basking on open rock faces, the chuckwallas' habit of lying almost totally flat provides two advantages. First, this posture enables them to absorb more heat. Second, the low-profile likely affords them greater camouflage from predators, especially air born predators, who will have trouble detecting either a chuckwalla or its shadow. In defending his territory, the male chuckwalla typically stages a bluff battle against a trespasser. By arching his back, lowering his head,and gaping his mouth, he will often intimidate the rival. He may also lash his tail and/or bite, if needed, to defend his territory.
3 males and 5 females
STATUS IN WILD:
Chuckwallas are relatively common, especially at the lower elevations in their range.