Evaporative Water Loss as a Restriction on Habitat Use in Endangered New Zealand Endemic Skinks

Abstract

Conservation efforts for two endangered lizard species, the chevron skink (Oligosoma homalonotum) and the striped skink (Oligosoma striatum), have been hindered by a lack of knowledge on their habitat preferences. Reports of some individuals being found in moist microenvironments has led to speculation that both species may be physiologically restricted to such habitats. Estimates of water loss in these two species were compared with water loss in two relatively common species, the speckled skink (Oligosoma infrapunctatum) and Falla's skink (Oligosoma fallai), that are inhabitants of semiarid habitats. When the effect of body size was accounted for using analysis of covariance, results indicated that chevron and striped skinks lost 34% more water through evaporation than the semiarid inhabiting species did. When compared to water loss rates in lizards elsewhere, all New Zealand species had relatively high rates of loss for their size. It is predicted that high rates of water loss in chevron and striped skinks would lead to these species preferentially inhabiting moist sites. Recommendations include that future survey effort for both species should be focused on areas with high moisture content. The results also raise implications for land management on Great Barrier Island and provide insight into the current distribution of chevron and striped skinks.