Desert Iguana

The desert iguana is a medium-sized lizard commonly found in the desert regions of North America. They have two peninsular and one continental subspecies.

These species were first described in the Catalog of North American Reptiles by American naturalist Spencer Fullerton Baird and French biologist Charles Frederic Girard in 1859 as Crotaphytus dorsalis. Two years later, it was reclassified as Dipsosaurus dofus dorsalis by American herpetologist Edward Hallowell.

Their scientific name is Dipsosaurus dorsalis, meaning thirsty lizard. The name comes from two Greek words, Dipsa meaning ‘thirsty’ and saurus meaning ‘lizard’. These herbivorous species can tolerate the extreme heat of the deserts and are active during the day.

Description

Length: 16–24 in (41-61 cm)

Weight: 0.125–0.188 lb (0.06–0.09 kg)

Body and Coloration: Body color is pale grey tan to cream with a pale belly. There is a light brown reticulated pattern on their back and sides, giving way to brown spots near the legs and stripes along the tail.

These lizards have blunt heads, large and oval earholes, well-built limbs, femoral pores, and long tails, The tail of a desert iguana is one and a half times longer than their body from snout to vent.

In the lower part of the body, there is a row of slightly-enlarged, keeled dorsal scales that become larger as they move down the back. A faint serrated crest runs from the neck to the tail. Their sides become pinkish during the breeding season. The males can be differentiated from the females by reddish markings near the tails.

Range and Distribution

They reside in the Mojave deserts of western United States including east-central California, western Arizona, southern Nevada, and southwestern Utah as well as the Sonoran desert region of California, Arizona, Northern Mexico, and Baja California. These species can also be found in the Gulf of California Islands.

Habitat

These species live in creosote bushes, sandy desert scrublands, and rocky streambeds. In the southern part of its range, they reside in arid subtropical scrubs and tropical deciduous forests.

Diet

The diet of the desert iguana is 54% plant-based and 44% animal-based. It consumes fruits, leaves, and buds. They are very fond of the yellow flowers of the creosote bush. Ants are very commonly consumed, occasionally eating other insects and carrion. The food they eat is their primary source of water.

Behavior

• Mainly terrestrial creatures but also good climbers, they often climb into the branches of bushes to fetch flowers.
• These animals dig extensive burrows in the sand under bushes like the creosote, inside which they can run and hide, when threatened. Sometimes, they use the burrows of other animals, like desert tortoises and kit foxes. The entrance of their caves is covered with sand, which protects them from predators.
• In winter, they hibernate and do not come out from their burrows. They emerge from hibernation in mid-March.
• They are active during the day and sleep at night.

Lifespan

The lifespan of wild desert iguanas is less than seven years, while the ones in captivity are more than seven years. The longest lifespan recorded in captivity is 14.6 years.

Adaptations

• Desert iguanas can tolerate the high desert temperatures between 40-46°C (104-115°F). They are active during the day to protect themselves from predators who cannot handle the scorching heat of the desert.
• They can inflate their bodies twice their size as a defensive display against predators. The predators cannot remove them from their crevices in this inflated state.
• They have tan and brown scales that provide perfect camouflage.
• Their tails can be autotomized to escape from predators.
• Desert iguanas are the fastest lizards on Earth. They can run at 30 miles/hour.
• These lizards have a third eye on the top of their head, which cannot discern colors and shapes but can sense light and movement. It helps them to anticipate predatory birds from above.

Mating and Reproduction

Desert iguanas are polygynous species. Males display dominant and aggressive behavior, competing for females and resources. A typical competition among them is push-ups.

The mating sites are cool microhabitats, and the mating season begins in spring and continues through mid-summer. The breeding mainly occurs in April and May, with 2-10 eggs being laid from late May to early July.

Oviparous by nature, the females usually lay one clutch of eggs per season, each containing 3–8 eggs. The eggs are hatched at temperatures of 28-38°C. The hatchlings are born around September.

Juveniles reach sexual maturity between 31–33 months of age. During the mating season, males and females exhibit pinkish pigmentation on both sides of their ventral surfaces.

Predators

The predators of desert iguanas are birds of prey, other birds like the loggerhead shrike, foxes, rats, long-tailed weasels, and snakes like coachwhips and sidewinders. The young ones are preyed upon by leopard lizards, collared lizards, and mammalian predators.

Conservation Status

The desert iguanas are listed as “Least Concerned” or “LC” by IUCN. The total population size of desert iguanas probably exceed 100,000 mature individuals.

Interesting Facts

• Desert iguanas are friendly to humans but can damage seawalls, sidewalks, and landscape foliage.
• They can bite humans in self-defense, tearing the skin instead of puncturing it.
• These species may carry a bacterial infection called Salmonella, transmitted from animals to humans.