GIENGER, C.M.*; TRACY, C. RICHARD: Geographic Variation in Activity of the Gila Monster.

The Gila monster (Heloderma suspectum) is a conspicuous, but infrequently encountered species distributed across the hot deserts of the the American southwest. It’s infrequent activity and low population densities make intensive field study difficult, and information regarding this species is limited. To determine patterns of geographic variation in temporal and spatial activity, we synthesized the results of previous studies conducted in Utah, Arizona, and New Mexico, and combined those with data from current field investigations in southern Nevada. We also gathered over 1000 collection records from more than 30 museums and natural history collections and compare them to field data. Throughout it’s range this species is most active in late spring and early summer (May and June), but activity in late summer (July and August) is variable depending on location, most likely in response to the onset of summer precipitation. Homeranges varied considerably by location, but because this species in somewhat uncommon, small sample sizes make interpretation of a geographic pattern of spatial activity difficult.