Endangered Species
Mountain-Prairie Region
GILA MONSTER

Gila monster

Species Description: The Gila monster is the largest native species of lizard in the United States.  Adults typically have a body length of 12-14 inches.  The tail is an additional 6-7 inches long.  It has rounded beadlike bony deposits on the back of its head, limbs, body, and tail; and a distinctive color pattern of black bands on a pale yellow or orange background on the body and tail. It has a massive skull, venom glands in the lower jaw, and a dark, forked tongue.

The Gila monster is one of only a few known species of venomous lizard, out of approximately 4,000 species of lizards worldwide.  It does not appear to inject venom into prey; instead, it most likely uses its venomous bite as a defense mechanism.  There are no documented cases of human mortality due to its bite.  Several components found in the venom of Gila monsters have valuable research and pharmacological applications including the treatment of Type 2 diabetes and possibly memory disorders such as Alzheimer’s disease.

They are slow-moving lizards that depend almost solely on vertebrate eggs and young in nests for food.  They can ingest large quantities of prey (up to one-third of their body weight) during a single feeding, and three large meals can supply the yearly energy demands of an adult. 

The Gila monster is found in portions of the Mohave Desert in southwestern Utah, southeastern Nevada, southeastern California, and northwestern Arizona; in the Sonoran Desert in southwestern Arizona and Sonora, Mexico; and in small portions of the Chihuahuan Desert in southeastern Arizona and southwestern New Mexico.  In Utah, it is found only in the southern portion of Washington County, which comprises less than one percent of the species’ total range.

The Gila monster favors rocky slopes, washes, and sandy valleys, with sites available for protection from weather extremes and predators.  It typically spends more than 95 percent of its time in underground shelters.

Recent Actions: June 2011:  The Service determined that a petition seeking to protect the Utah population of the Gila monster under the Endangered Species Act (ESA) does not contain substantial scientific information to indicate that the petitioned action may be warranted, because the population does not constitute a distinct population segment (DPS) as defined by the ESA.  Therefore, we will not conduct an in-depth review to consider whether the Gila monster should receive Federal protection under the ESA.

Despite this announcement that the species will not receive further consideration for listing under the ESA at this time, we will continue to work with our partners to conserve and protect the Gila monster throughout the species’ range.

More information can be found on the Service's ECOS website

Last updated: June 21, 2011