Winter Thermal Ecology of the Iguanid Lizard Tropidurus peruvianus

The iguanid lizard Tropidurus peruvianus was studied along an ocean cliff and beach in northern Peru during winter. T. peruvianus inhabit arid coastal areas of Peru providing refugia such as cliffs, rock outcrops and driftwood. Lizards first appear at burrow entrances between 0730 and 0800 hrs, but may delay activity as much as four hours if conditions are unsuitable. The number of lizards active in a morning is strongly correlated with air temperature. Daily activity is unimodal. Mean body temperature of active field lizards is 36.3 + 0.26 C; mean body temperature in a photothermal gradient is 35.6 ? 0.31 C. Body temperatures and activity patterns of T. peruvianus in winter seem tightly regulated compared with T. albemarlensis in summer on the Galapagos Islands. Eurythermy of T. albemarlensis may relate to the higher cost of thermoregulation in an environment with frequent cloud cover and to seasonal influences. Strategies of thermoregulation are outlined.