Spatial patterns and habitat use of penned and hard-released arboreal geckos translocated to an offshore island free of introduced mammals

Abstract

: Temporary penning prior to release is a strategy increasingly being used in lizard translocations to improve site fidelity and increase chances of translocation success. However, it is yet to be tested on a range of lizard taxa. Between 2015 and 2018, 49 individuals of a New Zealand endemic arboreal gecko species (ngahere gecko, Mokopirirakau “southern North Island”) were translocated to mammal-free Mana Island near Wellington as mitigation for a development project. Twenty-five of these geckos were tracked for this study with geckos being either hard-released ( n = 9) or released into a 0.52 ha pen for 10–31 months ( n = 16). Using radio-telemetry, we compared the behaviour, habitat use, dispersal, and home ranges of geckos from both groups in the weeks immediately following removal of the pen. Hard-released geckos travelled further from their initial release point and between location fixes than penned geckos. Hard-released geckos also had a larger home range size than penned geckos using both minimum convex polygons and fixed kernel methods, albeit with significant variation among individuals within each group. Habitat use was similar in both groups, but only hard-released geckos used grass, which was unexpected due to the arboreal nature of the species. In conclusion, our results support the use of penned-releases for translocations of arboreal geckos to restrict initial post-translocation dispersal and aid population establishment.