HABITAT REQUIREMENTS OF THE JEWELLED GECKO (NAULTINUS GEMMEUS): EFFECTS OF GRAZING, PREDATION AND HABITAT FRAGMENTATION

Understanding factors that influence the abundance of native lizards in ecosystems modified by invasive species is important, as today these ecosystems are globally abundant. Relationships between vegetation composition, livestock grazing and indicators of mammalian predation were examined for the native jewelled gecko, Naultinus gemmeus (Diplodactylidae) on the Otago Peninsula, South Island, New Zealand. Livestock grazing was expected to prevent the proliferation of rank grass (which is often associated with high rodent densities) and thereby reduce the frequency of predation by introduced rodents on jewelled geckos. Thus, activity of rodents was predicted to be lower and density of jewelled geckos higher at sites grazed by livestock. This was tested for two habitat types: shrubland dominated by Coprosma spp. and coastal forest dominated by kānuka (Kunzea ericoides). Abundance, density, detectability and incidence of tail loss in jewelled geckos were estimated using visual searches, photography and mark-recapture (POPAN formulation). Tracking tunnel surveys were undertaken at several sites to estimate the activity of introduced rodents