Gila monster Heloderma suspectum
ESA status: petitioned for listing (Utah populations)
Gila monsters move thoughtfully – their metabolic rates are the slowest of any lizard. The incredible combat rituals of male Gila monsters vying for females reflect their deliberate mentality. Instead of a brutal brawl, the two males engage in a prolonged, intertwined wrestling match that has been known to last up to 12 hours. Their goal is to maintain a superior position and pin their opponent to the ground. The victor retreats to a shelter with the female who has been waiting patiently nearby.
The Gila monster uses its finely tuned sense of hearing and its memory – a memory that may encompass up to 20 years of life – to find its prey. Gila monsters are very specialized and feed only on the eggs or nestlings of vertebrate animals. Though they are the only venomous lizards in the United States, as toxic as the Western diamondback rattlesnake, their venom appears to serve a primarily defensive role, and they are reluctant to bite unless provoked. Gila monster venom is also a complex chemical cocktail that contains substances used to treat diabetes and attention deficit disorders.
The Gila monster’s range stretches from southwestern Utah to Sonora, Mexico, where it meets up with the range of its larger cousin the beaded lizard. The Utah population of Gila monsters, a unique population at the very edge of the monster’s range, is in dire straits. Once host to one of the most abundant populations of Gila monster, the Mojave Desert habitat in southwestern Utah, in Washington County surrounding the city of Saint George, has lost most of its monster population to residential and commercial development driven by a burgeoning human population. The unique geological features and biological diversity that draw people to this amazing region have also resulted in a development boom that threatens its integrity. WildEarth Guardians is urging the federal government to grant Endangered Species Act safeguards to the Utah population of Gila monsters so that the stunning Mojave Desert environment doesn’t lose a species that is an integral part of its uniqueness.
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photo credit: Jeff Servass, U.S. Fish & Wildlife Service