Meeting Abstract
Many reptiles behaviorally regulate their body temperatures to increase energy assimilation and growth. However, some reptiles may limit thermoregulation due to increased predation risk associated with basking or other thermoregulatory activities. We investigate behavioral thermoregulation in juvenile gopher tortoises (Gopherus polyphemus), burrowing reptiles of the southeastern United States, and predict how thermoregulation and thermal environment influence growth. Since young tortoises are difficult to observe undisturbed, we used video cameras at burrows to quantify tortoise activities. Juveniles limit most basking activity to directly in front of their burrows from where they can quickly hide below ground to avoid predators. Juveniles shuttle in and out of burrows at predictable intervals to maintain preferred body temperatures. While juveniles generally only bask in front of burrows, they take advantage of most thermal opportunities available at these locations. In the lab, food intake and growth rate are highly temperature dependent across a narrow range of ecologically relevant temperatures and are greatest at the preferred body temperatures of fed tortoises. Therefore, by maintaining preferred body temperatures, juveniles can presumably increase their growth rates. Since young tortoises limit most basking to directly in front of their burrows, increased shading of their environment, stemming from fire suppression and other poor land management practices, may reduce tortoise growth rates and potentially result in adverse population-level consequences.
