Gila Monster

There are only two venomous lizards in the world, and both live in the Southwest; the Gila Monster and the Mexican beaded lizard.  The shy Gila Monster is one of seven reptiles species protected by Arizona law since 1952.  They are the surviving members of an ancient beaded lizard family, distinguished by their colorful beaded skins. Both species live in Sonora, Mexico, but only the Gila Monster can be found in the Sonoran and Mojave Deserts.  Seldom seen, these unusual creatures are living fossils, honored by primitive man, and if not carefully guarded doomed by civilized man.

Stores food in tail

Gila Monsters are large lizards with  stout bodies, big heads, powerful jaws, and short, sturdy digging legs.  They have big feet with large toes and long, strong claws.  Gila Monsters  grow to nearly two feet and have a black snout, short sausage-shaped tail and black tongue.  Their  body colors vary from black to coral pink to black with orange, yellow with cream.  Fat for future energy and metabolic water is stored in the tail as well as in the abdominal body.  A well-fed Gila Monster does not have to drink water and seldom does.  Its prey serves as its sole source of food as well as water.

Impressive appetite

Young Gila Monsters can consume more than 50 percent of their body weight in a single feeding, and adults, about 35 percent.  Gila Monsters like eggs, and they consume large quantities of Gambel’s quail eggs.   The lizard combines its powerful digging limbs, jaws and keen sense of smell to feed on the newborn and older nestlings of rodents; e.g. pack rats, and rabbits; e.g. antelope jackrabbit.  They occasionally swallow whole birds; e.g. cactus wren, and lizards; e.g. spiny lizard.

Venom is defensive weapon delivered by biting down with grooved and sharp-edged teeth in both jaws.  The Gila’s defensive bite does not deliver enough venom to be lethal.  However, the venom contains substances that quickly cause excruciating pain.  This weapon system is designed for defense rather than gathering food.

Summer rains are important

Summer rains effect underground egg-laying and successful foraging by the summer newborn. Mating takes place in the early summer, and females deposit from 6 to 13 eggs in a shallow depression dug in damp sand shortly before or during the rainy season in July and August.  There is a  year-long  incubation period.

Live in underground dens

Gila Monsters are sedentary reptiles that return year after year to the same cold-season home. Spending most of their time underground, they leave winter dens in the late spring and retire to the cooler, moist underground of lower valleys. The home range of a Gila Monster seldom exceeds more than a mile in any direction.  Being daytime creatures, they are strong climbers, posses good daylight vision and excellent hearing and are hard to fool when in familiar ground. Gila Monsters usually move slowly but they are not clumsy creatures and can be deceptively fast.