Environmental Influences on Space Use of Gila Monsters (Heloderma suspectum).

Organisms in highly dynamic environments may alter habitat use to cope with fluctuations in resource abundance and thermal regimes brought about by changing environmental conditions. We investigated how variation in environmental conditions affects Gila Monsters' (Heloderma suspectum) space use by analyzing variability in annual home ranges from 12 populations. Using very-high-frequency telemetry data, annual home-range estimates were calculated for each lizard using weighted autocorrelated kernel density estimation (wAKDE) and minimum convex polygon (MCP) methods. Publicly sourced environmental data were used to calculate annual estimates for 10 biologically important variables related to temperature, precipitation, productivity, and terrain ruggedness. Model selection analysis was used to identify top candidate models, and model averaging was performed to identify the variables most strongly associated with home-range size. We found a strong positive relationship between wAKDE home-range size and both winter precipitation and active-season temperature. MCP home-range size was negatively correlated with time-lagged summer precipitation and positively correlated with winter precipitation. Gila Monsters may exhibit behavioral adaptations to maximize annual resource intake during periods of resource abundance and decrease space use during resource scarcity to minimize energetic demands. [ABSTRACT FROM AUTHOR]