Thermoregulation in a nocturnal, tropical, arboreal snake

Abstract Few studies have focused on the thermal biology of tropical or nocturnal snakes. We recorded preferred body temperatures (Tb) of seven Brown Treesnakes (Boiga irregularis) in the laboratory and compared these to operative temperatures obtained with copper models and Tbs obtained by radiotelemetry from 11 free-ranging snakes on Guam. Operative temperatures on Guam did not vary across refuge types, unless the site received direct solar radiation. In a thermal gradient and on Guam, Brown Treesnakes thermoregulated around two distinct temperature ranges (21.3–24.9°C; 28.1–31.3°C). In the gradient, brown treesnakes exhibited elevated Tb into the higher range only in the evening. On Guam, snakes achieved Tbs in the high range only when direct solar radiation was available during the afternoon, a period when snakes were inactive. Higher mean Tbs on sunny days corresponded with observations of basking behavior.