HEAT, SAFETY OR SOLITUDE - USING HABITAT SELECTION EXPERIMENTS TO IDENTIFY A LIZARDS PRIORITIES

Laboratory experiments with a rock-dwelling nocturnal gecko, Oedura le suerii, showed that retreat-site selection (and other behaviours) are affected by the interplay between thermal benefits, social advantages and avoidance of predators. Velvet geckos were highly selective in hab itat choice: they preferred artificial retreat-sites that mimic the th ermal properties of natural rocks in full sun rather than those that m imic rocks in full shade. mature male geckos rarely shared retreat-sit es with other adult males: and these lizards strongly avoided retreat- sites covered with the scent of a natural predator (the broadheaded sn ake, Hoplocephalus bungaroides), After documenting these preferences? we carried out additional trials in which two or more of these factors co-occurred, as is often the case in nature. Social dominance interac ted with thermal benefits in determining retreat-site selection, with smaller (subordinate) males forced to use cooler retreat-sites when la rger (dominant) males were present. Avoidance of predators was a highe r priority than thermoregulation: the lizards would forego a warmer re treat-site with predator scent in favour of a cooler, unscented one. T here was also an interplay between social dominance and predator scent : smaller males were forced to use either predator-scented retreat-sit es or no retreat-site when larger males were present. General activity levels, and the frequencies of specific behavioural acts, also shifte d in response to social and predator-scent cues. Our study emphasizes the complexity of habitat-selection behaviour in these lizards, and cl arifies the criteria used in retreat-site selection when (as is common ly the case) the animal must choose between conflicting priorities. (C ) 1998 The Association for the Study of Animal Behaviour.