The Gila monster is a species of venomous lizard native to the Southwestern US and Northwestern Mexico. A heavy, typically slow-moving lizard, up to 60 cm long, the Gila monster is the only venomous lizard native to the United States. Although the Gila monster is venomous, its sluggish nature means it represents little threat to humans. In 2019, the state of Utah made the Gila monster its official state reptile.
Gila monster is the largest extant lizard native to North America. Its snout-to-vent length is 26 to 36 cm. The tail is about 20% of the body size and the largest specimens may reach 51 to 56 cm in total length. Body mass is typically in the range of 350 to 700 g.
The name “Gila” refers to the Gila River Basin in the U.S. states of New Mexico and Arizona, where the Gila monster was once plentiful.
The Gila monster eats small birds, small mammals, frogs, smaller lizards, insects, and carrion. The Gila monster feeds primarily on bird and reptile eggs. It uses its extremely acute sense of smell to locate prey, especially eggs. Its sense of smell is so keen, it can locate and dig up chicken eggs buried 15 cm deep and accurately follow a trail made by a rolling egg.
The venom of the Gila monster is about as toxic as a Western diamondback rattlesnake. But, Gila monster produces the venom in small quantities. The Gila monster’s bite is not fatal to healthy adult humans. The Gila monster can bite quickly and hold on tenaciously and painfully.
The female lays eggs in July or August, burying them in sand 13cm below the surface. The clutch consists of 2 to 12 eggs. The incubation lasts nine months, as the hatchlings emerge during April through June the following year. The hatchlings are about 16cm long and can bite and inject venom upon hatching. The juveniles typically have larger bands of pink scales than adults, although the banded Gila monster has a tendency to retain the band pattern.