Responses at the source and release site following an inter-island translocation of Leiopelma hamiltoni

Abstract

The use of translocations for conservation management has increased in frequency over recent decades. Though many early translocations were carried out as one-off management exercises, the need to test release strategies and gain knowledge in order to improve future reintroductions has been recognised. This study examined both the movements and survival of 101 Leiopelma hamiltoni (Anura: Leiopelmatidae) translocated to Long Island, New Zealand, and the response of the source population on Te Pākeka/Maud Island to the removal of a discrete subset of frogs. An experimental approach was taken to test whether familiarity would improve anchoring to the site and discourage homing and dispersal post translocation. Frogs translocated with their neighbours did not stay with those individuals and those that were released in a random pattern did not move towards their former Maud Island neighbours. While initial movements were significantly oriented to the bearing of Maud Island, after several months this had changed to indicate that the frogs moved in a downhill direction. Capture-recapture abundance estimates suggest a decline in the population of translocated frogs during the 46 months post-release and follow up surveys 10-13 years post-release confirm that this translocation failed. Capture-recapture abundance estimates suggest that the 240 m 2 grid emptied of frogs (i.e. the source population) took one year to return to pre-translocation densities. There is little doubt that translocations will continue to be an important tool for the conservation management of leiopelmatid frogs in New Zealand and for amphibians worldwide. However, a commitment to post-release monitoring, use of methods that allow for causes of failure to be assessed, and testing release strategies is imperative to informing methods and improving the success rates of future translocations.