Despite public fascination with the Gila monster, relatively little is known about this large lizard. The slow moving and lethargic Gila monster spends most of its time in underground burrows. The total amount of time spent on the Earth's surface may add up to only three weeks a year. For this reason, Gila monsters are rarely seen by visitors at Tonto National Monument.
The Gila monster can be found across most of western and southern Arizona, often above rocky drainages and rugged slopes. Typically, their shelter sites are burrows dug under boulders and small rock outcrops.
Gila monsters are carnivores that feeds on small mammals, birds, the eggs of birds and reptiles, lizards, and carrion. When they hunt, they flick their forked tongue to pick up scent particles in the air. It is necessary for the Gila monster to sneak up on their prey and bite them before they get away. At Tonto National Monument, they have been observed eating a clutch of six Gamble's quail (Callipepla gambelii) eggs and a young desert cottontail (Sylvilagus audubonii). Storing fat in their tails, Gila monsters can survive for an entire year on three to four meals.
Males compete for choice mates by engaging in wrestling matches, in which the biggest and strongest wins. In late summer, females lay three to five eggs. The eggs incubate and develop from fall to spring; young appear the following April through June.
It is against Arizona State law to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect the Gila monster or to attempt to engage in any such conduct.