Desert iguanas are equipped with femoral pores that absorb ultraviolet wavelengths and then produce fluorescent chemicals that are used as territory markers. These markers are only visible to species that can detect ultraviolet wavelengths. Little is known about sensory perception in desert iguanas. They appear to have color vision, as demonstrated by their affinity for yellow flowers, yellow mealworms and yellow flagging tape. They also are able to communicate through aggressive displays, such as push-ups.
Communication Channels: visual ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; ultraviolet; tactile ; acoustic ; chemical
The IUCN Red List classifies desert iguanas as a species of least concern. It is estimated that their population exceeds 100,000 adults. Some local populations have experienced decline due to habitat destruction and highways.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Currently, there is no information available regarding specific aspects of the development and life cycle of desert iguanas.
Development - Life Cycle: indeterminate growth
There are no known adverse effects of desert iguanas on humans.
Desert iguanas often serve as pets for humans and are also used in research.
Positive Impacts: pet trade ; research and education
Desert iguanas are a food source for the predators in their geographic range, including foxes, raptors, and snakes. Desert iguanas also serve as hosts to a number of parasitic microbes. In order to keep the microbes from excessively multiplying and causing internal damage, infected desert iguanas maintain higher than normal body temperatures. If an infected individual is prevented from achieving a higher internal body temperature, then the microbes can have detrimental effects. Aside from these microbes, there are currently no known parasites specific to this species.
Commensal/Parasitic Species:
Desert iguanas are primarily folivores, but will also occasionally eat insects. They feed on the buds, leaves and flowers of a variety of annual and perennial plants, with vegetation making up over ninety percent of their diets. The types of plants eaten change seasonally. In spring they will particularly eat yellow flowers, especially those of the creosote bush (Larrea tridentata). Alfalfa leaves (Medicago sativa) are also a part of their diet, as are the feces of other herbivores. Occasionally they will eat arthropods, such as crickets and mealworms, but this behavior is rare in the wild. Captive desert iguanas will eagerly consume yellow mealworms, with wild individuals also taking mealworms, when offered. Desert iguanas in captivity have also been known to eat dandelion flowers (Taraxacum sp). They have even been observed eating yellow flagging tape, which suggests that the color yellow plays an important role in their foraging strategy.
Animal Foods: insects
Plant Foods: leaves; fruit; flowers
Other Foods: dung
Primary Diet: herbivore (Folivore ); coprophage
Desert iguanas are endemic to the Sonoran Desert of the Southwestern United States and Northern Mexico and to the Mojave Desert of the Western United States. They can also be found on several islands in the Sea of Cortez.
Biogeographic Regions: nearctic (Native )
Desert iguanas inhabit desert environments. Their preferred habitats include creosote flats and thornscrub forests. They are terrestrial animals but are capable of climbing at least one meter above the ground in creosote bushes. They are capable of withstanding high temperatures and are often active during the hottest part of the day, becoming less active when the sun is not shining. They are most active at 40°C (104°F) and are capable of handling temperatures up to 46°C (115°F). Higher temperatures, ranging from 55° to 60°C (131° to 140°F) are fatal. When inactive or at night, they take shelter in small mammal burrows, usually found at the base of creosote bushes or cacti.
Range elevation: Below sea level to 5,000 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; scrub forest
The lifespan of desert iguanas in captivity averages about 7 years, with the longest lifespan recorded in captivity being 14.6 years. Little is known about the lifespan of wild individuals, although it is likely to be less than those in captivity.
Range lifespan
Status: captivity: 14.6 (high) years.
Average lifespan
Status: wild: less than 7 years.
Average lifespan
Status: captivity: 7 years.
Desert iguanas are medium-sized lizards. They have a stout, rounded body with a small head. Their snout to vent length (SVL) is about 13 cm (5.25 inches). Their tail is long and tapered, and generally measures a little less than twice the body length. They are typically 33 to 36 cm in total length (13 to 14 inches), with a maximum overall length of 40.6 cm (16 inches). Hatchling desert iguanas are only about 3.75 inches long. Desert iguanas have a grayish brown coloring with a reticulated dark, reddish brown pattern on their dorsal surface. Their ventral surface is a pale gray or cream that lacks any reticulations. The tail is decorated with small reddish brown dots. Both female and male desert iguanas exhibit areas of pinkish pigment on their lateral-ventral surfaces during mating season. Female and male desert iguanas appear very similar to one another, although males are usually characterized by reddish markings near their tails. Desert iguanas have fine, granular dorsal scales and a faint serrated crest that runs from the neck onto the tail. Desert iguanas have large, oval ear holes, well formed limbs, and are equipped with femoral pores that are used for marking territory.
Average mass: 69.5 g.
Range length: 33.02 to 40.64 cm.
Sexual Dimorphism: sexes colored or patterned differently; male more colorful
Raptors, snakes, and foxes are all predators of desert iguanas. Coachwhip snakes (Masticophis flagellum) are also a major predator of desert iguanas and other lizards in the Sonoran Desert of the Southwestern United States. The desert iguana’s grayish-brown body coloring is advantageous for desert environments and may act as camouflage. Desert iguanas will retreat to their burrows when threatened, but are also capable of inflating themselves to keep from being pried out of their hiding places. In the open, this behavior allows them to seem larger and discourage predators. Desert iguanas also have autotomous tails which, when lost, distract their predators and potentially allow the lizard to escape.
Known Predators:
Anti-predator Adaptations: cryptic
Desert iguanas are a polygynous species. Their mating system centers around the cooler microhabitats created by the creosote bushes and other desert shrubs. The bushes and shrubs are a major food source for desert iguanas but they also provide the coolest midday temperatures and females develop their home ranges around them. Desert iguanas are a territorial species and aggression between sexually mature males competing for females and resources is common. Aggressive displays between males that are designed to attract females often include push-ups, as in many other iguanid species. Dominant males will also establish their territory around desert shrubs, allowing better access to more females.
Mating System: polygynous
The breeding season begins in spring and continues through midsummer. Peak breeding intervals occur in May and June. Desert iguanas are oviparous, usually laying eggs in early to late summer. Females generally lay one clutch of eggs per season, although under optimal conditions they can lay two clutches per season. Egg clutches typically contain from three to eight eggs. Females dig burrows in the ground, then position themselves over the burrow to deposit their eggs. The eggs are then covered with soil and left alone. Desert iguanas reach sexual maturity around 31-33 months of age. Both male and femalese exhibit pinkish pigment on the sides of their ventral surfaces during mating season. There is little known about the actual reproductive process and gestation in this species.
Breeding interval: Desert iguanas generally breed once a year, although they may breed twice if conditions are optimal
Breeding season: Copulation typically occurs in May and June
Range number of offspring: 3 to 8.
Range age at sexual or reproductive maturity (female): 31 to 33 months.
Range age at sexual or reproductive maturity (male): 31 to 33 months.
Key Reproductive Features: seasonal breeding ; oviparous
Desert iguanas provide very little parental investment for their offspring. Females will dig a burrow, lay the eggs, and cover them. Once the eggs hatch there is no parental involvement.
Parental Investment: no parental involvement; pre-hatching/birth (Provisioning: Female)
