Chuckwalla Sauromalus

Widely distributed throughout the Mojave Desert, Chuckwallas are large lizards found primarily in arid regions of the southwestern United States and northern Mexico. Some are found on coastal islands. There are five species of chuckwallas, all within the genus Sauromalus; they are part of the iguanid family, Iguanidae.
The common name chuckwalla derives from the Shoshone word “tcaxxwal” or Cahuilla “caxwal,” transcribed by Spaniards as “chacahuala.”
The generic scientific name, Sauromalus, is a combination of two Ancient Greek words:σαῦρος (sauros) meaning “lizard”. and ομαλυς (omalus) meaning “flat.”
Chuckwallas are a stocky wide-bodied lizard with a flattened midsection and prominent, rounded belly. Their tails are thick, tapering to a blunt tip, and will regenerate if detached. Loose folds of skin characterize the neck and sides of the body, which is covered in small, coarsely granular scales. The common chuckwalla (Sauromalus ater) measures 15 3/4 inches in length.
They are sexually dimorphic with males having reddish-pink to orange, yellow or light gray bodies and black heads, shoulders, chest and limbs. Sometimes the dark coloring is covered with light spots and flecks. Females and the immature have bodies with scattered spots or contrasting bands of light and dark in shades of gray or yellow. Males are generally larger than females and possess well-developed femoral pores located on the inner sides of their thighs; these pores produce secretions believed to play a role in marking territory. The body and tail of young chuckwallas are more prominently banded with dark and yellow coloring.
The genus Sauromalus has a wide distribution in the desert environment of the Sonora and Mojave. The common chuckwalla (Sauromalus ater) is the species with the greatest range, found from southern California east to southern Nevada and Utah, western Arizona and south to Baja California and northwestern Mexico. The peninsular chuckwalla (Sauromalus australis) is found on the eastern portion of the southern half of the Baja California Peninsula.
The other species are island-dwelling and therefore have much more restricted distributions. The Angel Island chuckwalla (Sauromalus 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 – the Montserrat chuckwalla (Sauromalus slevini) and and the San Esteban chuckwalla or painted chuckwalla (Sauromalus varius) – are found, respectively, on Islas Carmen, Coronados and Montserrat in the southern Gulf of California and on San Esteban Island, Lobos and Pelicanos.
Chuckwallas prefer lava flows and rocky areas, ones typically vegetated by creosote bush and other such drought-tolerant scrub. They range to elevations as high as 4,500 feet.
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).
Harmless to humans, these lizards are known to run from potential threats. When disturbed, a chuckwalla will use its rough skin and strong claws to entrench itself tightly into a crevice, sometimes inflating its lungs in order to wedge its thick midsection.
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-hobbing, and gaping of the mouth, to communicate and defend their territory.
Chuckwallas are diurnal animals and ectothermic, spending much of their mornings and winter days basking. These lizards are well adapted to desert conditions; they are active at temperatures of up to 102 °F (39 °C). Juveniles emerge first, then adults, as temperatures reach around 90 °F. Chuckwallas hibernate during cooler months and emerge in February.
Mating occurs from April to July, with five to 16 eggs laid between June and August. The eggs hatch in late September. Females may skip one or two years between laying eggs. Chuckwallas may live for 25 years or more.

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