Thermal and physical characteristics of the nesting habitat of New Zealand’s only endemic oviparous lizard

Nest characteristics and nest-site choice determine fitness outcomes for reptile embryos and resulting hatchlings. Little is known about the nesting of Oligosoma suteri, New Zealand’s only egg-laying lizard. We investigated the physical and thermal environment of nests and available microhabitats, including nest-like sites, with the aim of applying this information to future search efforts and translocation plans. Nests of O. suteri were difficult to locate in known nesting habitat occupied by a self-sustaining population; only 0.42 nests were found per person-hour of searching during mid-January on Korapuki Island, and several of these nests were likely communal. All eggs were partially buried in a fine, sandy-silt substrate beneath a rock and were within 2 m of overhanging vegetation. Thermal profiles of these nests and three mock nests chosen with similar physical characteristics result in incubation lengths observed in successful lab-based incubation studies. Our outcomes support lab-based evidence that females select nest sites based on temperature as temperature data loggers deployed at other parts of the beach recorded temperatures that are outside the known successful incubation temperatures. We recommend investigating thermal conditions at proposed translocation sites, including sites outside the species’ current range so that predictions can be made regarding population viability should the species need to be moved south due to loss of habitat under future climate change scenarios.