The Herpetological Journal

pp.137-146 

Authors: Roger Meek

Abstract: Observations were made on the thermoregulatory behaviour and activity patterns of Physignathus cocincinus in a simulated tropical environment. P. cocincinus is a sit-and-wait predator with movement restricted to a maximum of 9 or 10 bursts of activity per day. Both terrestrial and aquatic activity were temperature dependent, and were greatest in hot, sunny weather. When the weather was overcast, the lizards spent most of their time in open areas and at higher levels in the canopy; increased sunshine induced movement to lower levels, with more time spent in shade. Regression analysis of the relationship between lizard and model temperatures was used to determine thermoregulation. P. cocincinus is basically a thermoconformer, but needs to thermoregulate on sunny days to avoid excessive heat loads. Control of body temperature during hot and intermittent sunshine was principally achieved by seeking shade and partial basking. On cloudy days the animals were thermoconformers, as environmental temperatures were sufficiently high to enable locomotory activity and feeding to take place, but not so high that excessive heat loads became a problem.

Keywords: Physignathus cocincinus, thermoregulation, activity patterns