Meeting Abstract

18.5  Saturday, Jan. 4 11:15  Exploring the energetics of foraging behavior in Gila monsters, Heloderma suspectum WRIGHT, C.W.*; MOELLER, K.T.; HOLDEN, C.; DEMARE, G.; DENARDO, D.F.; Arizona State Univ., Tempe; Arizona State Univ., Tempe; Arizona State Univ., Tempe cdwright729@gmail.com

Although predation risk and food availability strongly influence foraging decisions, so too can physiological condition and the energetic costs associated with searching for a meal. The interaction between physiological condition, energetic costs of searching for a meal, and foraging decisions is often referred to as state-dependent foraging (SDF). Although SDF is well studied in organisms with high-energy budgets (e.g., mammals), studies examining SDF in infrequently feeding organisms with low-energy budgets are rare. To better understand the interaction between condition, foraging behavior, and energetic costs associated with foraging, we examined how varying energy intake effects the foraging expenditures and behavior of a low-energy organism by supplementally feeding free-ranging Gila monsters, Heloderma suspectum. We used doubly labeled water to estimate field metabolic rate and implanted temperature loggers to record hourly body temperature and to estimate surface activity using temperature-based activity estimation (TBAE). As one determinant of foraging decisions is the energetic cost of searching for a meal, whereby high energetic costs may reduce the time an organism will dedicate to foraging, we used our field data in conjunction with lab-based measurements of the thermal sensitivity of standard metabolic rate to distinguish energetic expenditures during refuge use and surface activity. Here we present the results of our study and discuss how the foraging behavior of this low-energy organism compares to those of high-energy organisms.