Edelkind, J. L.
Department of Biology
Austin Peay State University
Clarksville, Tennessee, USA
Stalker, J. B.
Tennessee Aquarium
Chattanooga, Tennessee, USA
D. D. Beck - Central Washington University; D. F. Denardo - Arizona State University; P. G. Emblidge -
Oregon State University; C. M. Gentry - Austin Peay State University; M. J. Goode - University of
Arizona; J. L. Jones - Nevada Department of Wildlife; M. A. Kwiatkowski - Stephen F. Austin State
University; E. M. Nowak - Northern Arizona University, R. A. Repp - National Optical Astronomy
Observatory, Tucson, Arizona; G.W. Schuett - Georgia State University and Chiricahua Desert Museum;
B. K. Sullivan - Arizona State University, West Campus; L. I. Gallardo- West Valley College; R. D.
Jennings - Western New Mexico University; and C. M. Gienger - Austin Peay State University
Organisms in environmentally dynamic habitats may alter aspects of habitat use to cope with fluctuations in resource abundance brought about by changing environmental conditions. The Gila Monster (Heloderma suspectum), a native of the dynamic deserts of the southwestern United States, is a highly philopatric and long-lived species that maintains a well-defined home range across years. We investigated how variation in environmental conditions impacted Gila monster spatial ecology by analyzing variability in home ranges from twelve populations across Arizona, New Mexico, Utah, and Nevada. Using GPS telemetry data, annual home range utilization distributions were calculated for each lizard using a weighted autocorrelated kernel density estimator. Publicly sourced environmental data was used to calculate annual and seasonal estimates for ten biologically important environmental variables related to temperature, precipitation, and terrain ruggedness. Model selection analysis was used to identify top candidate models, and model averaging was performed to identify the environmental predictor variables that were most strongly associated with home range size. Home range size was most strongly associated with winter precipitation (β=0.191, P<0.001), active season temperature (β=0.499, P=0.001), and vegetation productivity (β=0.357, P=0.007). Home range size was positively correlated with all three variables, countering predictions of hypotheses associated with resource abundance and thermal tolerances. Gila Monsters may be employing an energy intake maximization strategy wherein individuals increase home range size during periods of resource abundance to maximize resource (food and water) intake. Periods of resource scarcity would prompt a decrease in home range size to reduce energetic demands, allowing individuals to wait out periods of resource scarcity while using stored energy reserves.