Evaluating translocation success using hard and soft release methods for an arboreal gecko, 8–11 years after translocation

Understanding the long-term implications of translocation methods is essential when refining best translocation practices for a species. High rates of movement and dispersal away from release sites have been key concerns when hard releasing lizards. A recent proliferation of research on translocation of New Zealand’s endemic green geckos (Naultinus spp.) has confirmed that penning for at least four months promotes initial site fidelity. Using a standardised, staged framework previously applied to other species of New Zealand herpetofauna, we assessed the stage of translocation success for one hard release (n = 11) and two soft releases (n = 32 and 42) of jewelled geckos (N. gemmeus), 8–11 years following release into the fenced Orokonui Ecosanctuary. We conducted 75 visual surveys on sunny days when geckos were expected to be basking. Suitable jewelled gecko habitat within a c. 50 m radius of the release sites and habitat between sites was visually searched. Founders were identified through photo identification, and linear distance from release location was estimated. Eighty geckos were located (including 13 founders from across the three release cohorts). Stage 3 of translocation success (population growth) is suspected to have been reached at both the 2012 hard and soft release sites. The release method used had no detectable effect on the number of geckos found or the stage of translocation success reached 8–11 years since release. Contrary to the reported short-term failure of many hard release lizard translocations, including all hard releases of Naultinus species, our findings confirm that hard release can enable population establishment and likely population growth as well. Understanding the drivers behind the establishment of a hard released population may enable further development and reduce the costs associated with the translocation of Naultinus species and other arboreal lizards with small home ranges.