Ontogenetic differences in the preferred body temperature of the European adder Vipera berus

"We tested the hypothesis that the costs of thermoregulation (e.g. predation) can affect the preferred body temperature (T-P, the ""target"" body temperature in thermoregulation) of reptiles. In European adders (Vipera berus), juveniles face higher predation risks than adults. We compared T-P between adult and juvenile adders and found that the T-P of juveniles was approximately 5 degrees C lower than that of adults, while adult males and females did not differ. All groups were characterized by narrow T-P ranges. Our results suggest that reptiles may change their T-P in response to the high ecological costs of thermoregulation. Alternative explanations for the reported pattern are also discussed."