Meeting Abstract

102.5  Tuesday, Jan. 7 09:00  Does Burrow Temperature Constrain Antipredator Behavior in Juvenile Gopher Tortoises? RADZIO, T.A.*; O’CONNOR, M.P.; Drexel University; Drexel University tar55@drexel.edu

Ectotherms may experience a tradeoff between predator avoidance and thermoregulation, particularly when refuge temperatures are physiologically suboptimal. Theory predicts that ectothermic prey will adjust hiding times following unsuccessful attacks to optimize the benefits (predator avoidance) and costs (e.g., reduced physiological performance) of refuge use. Tests of this hypothesis have primarily focused on lizards, organisms that often engage in precise behavioral thermoregulation. We examined how temperature influences hiding time in juvenile gopher tortoises Gopherus polyphemus, which are not known to be precise thermoregulators. We found that juvenile gopher tortoises engage in extensive behavioral thermoregulation by frequently shuttling between relatively cool burrow and warm surface microhabitats. In simulated predator approaches that used video cameras to document tortoise responses, basking juveniles exhibited long flight initiation distances and entered burrows rapidly. These observations suggest that individuals rely on both early, non-visual detection of predator presence and rapid escape speed to avoid attack. Burrow temperatures explained variation in reemergence times, with juvenile tortoises reemerging sooner when burrows were cool and remaining below ground longer when burrows were warm. These results suggest that, similar to some lizards, juvenile gopher tortoises appear to optimize a tradeoff between predator avoidance and physiological performance.