Field Guide to Reptiles
of Southern California
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Gila Monster (Heloderma suspectum)
The Gila monster is widely distributed in the southwestern U.S. In California, it is uncommon in a variety of desert woodland and scrub habitats in the extreme eastern Colorado and Mojave deserts in a few isolated localities, principally in desert mountain ranges. This lizard prefers the lower slopes of rocky canyons and arroyos but is also found on desert flats among scrub and succulents. It seems to prefer slightly moist habitats in canyons, arroyos and washes. It is probably not abundant anywhere in California, and there are very few well-documented records for the state. In California it is probably only active in spring, summer and early fall, although it is active all year in the southern parts of its range.
The Gila monster utilizes the burrows of other animals and may construct its own. Rock crevices and boulder piles are also used for shelter (Shaw 1950, Stebbins 1954, Bogert and Del Campo 1956).
Little is known about reproductive requirements. Eggs are laid in the soil in excavated nests, so the soil must be sandy or friable. Gila monsters may also require areas with exposure to the sun, and moisture (Stebbins 1954, Bogert and Del Campo 1956). One captured female contained 5 ovarian eggs. Incubation requires 1 month (Stebbins 1954).
This lizard is active at night and sometimes at dusk. In California it probably becomes active in mid-spring, staying abroad through the summer (Stebbins 1954). Little is known of the seasonal movements of this species. It probably does not migrate.
Diet and Foraging
These lizards are opportunistic feeders, taking nestling birds, rodents, small rabbits and squirrels, lizards, eggs of birds and reptiles, and possibly carrion. They seem to take anything that can be found on the ground, underground or in bushes (Stebbins 1954, Bogert and Del Campo 1956).
No data available.
Amateur herpetologists prize this species highly and will capture it whenever possible, thus increasing its rarity in California.
Bogert, C. M., and R. M. Del Campo. 1956. The Gila monster and its allies. Bull. Am. Mus. Nat. Hist. 109:1-222.
Shaw, C. E. 1950. The Gila monster in New Mexico. Herpetologica 6:37-39.
Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw-Hill, New York. 536pp.
Storer, T. I. 1931. Heloderma poisoning in man. Bull. Antivenin Inst. Am. 5:12-15.
Information gathered from California DFG - California Interagency Wildlife Task Group