Species Fact Profile: San Esteban Chuckwalla (Sauromalus varius)

San Esteban Chuckwalla

Sauromalus varius (Dickerson, 1919)

Range: San Esteban Island (Gulf of California)
Habitat: Desert
Diet: Leaves, Fruits, Flowers
Social Grouping: Males form hierarchies and harems
Reproduction: Mating season is April through June.  Up to 16 eggs laid between June through August; eggs hatch around September.
Lifespan: 25 Years
Conservation Status: CITES Appendix I

• Largest of the five chuckwalla species, an example of island gigantism.  Body length up to 60 centimeters, total length up to 75 centimeters.  Body weight up to 2 kilograms.  Males tend to be larger than females
• Skin color is gray with yellow or tan patches, with a darker face.  Females are duller than males with fewer patches
• When threatened, the chuckwalla will run into a rock crevice and inflate its body to make it more difficult to extract; they will also wedge themselves in with their tail and claws
• Males are territorial, displaying dominance over other males by head-bobbing and doing push-ups atop rock heaps.  Territories are marked using scent glands on the legs.  Males become more territorial during times of plenty, less so during times of scarcity
• Gain all of their water from the plants they eat; don't urinate, excrete salty crystals instead
• Name "Chuckwalla" comes from the Shoshone name for the animal.  The Latin name translates to "Flat Lizard with Speckling"
• Locally common, but considered endangered due to its very limited geographic range.  In the language of the Seri people, San Esteban is called the "Island of the Giant Chuckwalla"
• The Seri translocated these lizards to several others islands as a food source (sometimes crossbred with other chuckwalla species); none of these populations have survived to the present that
• Threatened by the introduction of invasive predators and competitors, as well as over-collection for the pet trade.  Sometimes killed by humans who mistake them for Gila monsters