Thermal properties of artificial refuges and their implications for retreat-site selection in lizards

Artificial retreats or refuges (ARs) provide a useful method for sampling lizards and a possible means of restoring habitat to aid population persistence. Previous research suggests that preferences for ARs may vary among species and between different disigns. To test these ideas further. we examined the influence of thermal and structural characteristics on use of three types of ARs by the noeturnal common gecko (Hoplodactylus maculatus) and diurnal McCann's skink (Oligosoma maccanni). two lizards endemic to New Zealand. The field study confiremed that the three ARs (triple-layered Onduline, triple-layered iron, solid concerete) differed in retreat-site temperatures provided during of three seasons (winter, spring and summer) provided field temperatures within thhe thermal preference range of both species (data obtained from the literature) but only for the top spaces of the ARs and onluy during summer. Onduline was the only AR to consistently provide the temperatures preferred by pregnant females. Although this study suggests that structural properties alone may be sufficient to explain the preferene of geckos for triple-layers Onduline stacks, it does not eliminate the possibility that attractive thermal properties also contribute. Long-term studies are needed to test the effects of artificial refuge supplementation on reptiles. and on their predators and competitors.