The role of ecological restoration in the conservation of Whitaker's skink (Cyclodina whitakeri),a rare New Zealand lizard (Lacertilia: Scincidae)

Abstract

Abstract A programme to improve the conservation status of Whitaker's skink (Cyclodina whitakeri), previously confined to <20 ha of usable habitat, is described. The programme involved eradication of introduced Pacific rats orkiore (Rattus exulans) from 18 ha Korapuki Island (Mercury Islands, north‐eastern New Zealand), documentation of the response of five species of resident lizards to release from the effects of rats, and transfer of 28 Whitaker's skinks from nearby Middle Island between 1988 and 1990. Following removal of rats from Korapuki, resident lizard numbers at some coastal sites increased within 12 months and rose 30‐fold over 5 years, but measurable increases of numbers of lizards in forest areas took up to 6 years. Fifteen of the founding Whitaker's skinks on Korapuki Island have been recaptured 36 times since their release, and five Korapuki‐born young have also been caught. The population is now estimated as 33. The increase in number of resident lizards and the success of the introduction of Whitaker's skinks demonstrate that predation rather than habitat deficiencies were responsible for the depleted resident lizard fauna on Korapuki Island. Repatriation strategies for species with low intrinsic rates of increase are proposed.