Food and habits
Food consists chiefly of bird and reptile eggs, young rodents, and such small or juvenile creatures as it is able to capture. It is especially fond of hen eggs and may be kept in captivity for a long time without other food. It is also fond of clear water, which seems strange because of the scarcity of this liquid in the natural habitat of the lizard. If provided with a basin of water it may lie partly submerged for hours.
Occasionally encountered ambling across stretches of open desert, especially in the spring, the Gila monster is normally docile and bends every effort toward escape among the stiff stems of some bush or beneath the protecting spine-clad stems of a cactus plant. Sometimes an individual with a “chip on its shoulder” may be met, or one in a normal state of mind may be teased or prodded into anger, when it advances with open mouth, sputtering and hissing.
When aroused, the Gila monster is remarkably agile, making quick turns of its head to snap at nearby objects. If it secures a grip, it hangs on with bulldog-like tenacity, grinding the object between its teeth.
Gila monsters reproduce by means of eggs which are about 2½ inches long with a tough, parchment-like skin. From 5 to 13 eggs are deposited by the female in a hole which she scoops in moist sand in a sunny location. After laying the eggs, she covers them with sand, and leaves them for the heat of the sun to hatch.
Poison mechanism of the Gila monster Redrawn from Dr. Fox
1. Poison gland. 2. Grooved tooth. 3. Poison duct. 4. Opening, poison duct. 5. Eye. 6. Dissected lower jaw.
The Gila monster’s tail serves as a storehouse of nourishment, being thick and heavy in times of plenty, and thin and rope-like in the early spring when the reptile first appears after months of hibernation, during which time it has lived on the reservoir of fat stored in its tail.