Lessons learned from a series of translocations of the archaic Hamilton’s frog and Maud Island frog in central New Zealand

Summary

Hamilton's frog (Leiopelma hamiltoni) and Maud Island frog (Leiopelma pakeka), among the most evolutionarily ancient living frogs and once each confined to a single tiny remnant site in New Zealand's Marlborough Sounds, have been the subject of a series of translocations since 1984 testing different transfer strategies across predator-free islands. The pioneering 1984-1985 transfer of 100 L. pakeka to Boat Bay on Maud Island proved highly successful, with 75% of founders recaptured after six months, rising body condition and size, and by 2010 at least 136 locally-bred recruits exceeding the founder number, with 34% of founders still alive after 25-26 years. Building on that model, later transfers moved 300 L. pakeka to Motuara Island in 1997 (breeding confirmed by 2002), 40 L. hamiltoni to Nukuwaiata Island in 2004 with 31 more in 2006 (first recruit found 2008), and 101 L. pakeka to Long Island in 2005, though that population appeared to decline after four years, possibly from poor habitat and kiwi predation. A 2006-2007 introduction of 60 captive-held L. pakeka into Wellington's fenced Zealandia sanctuary saw high survival within a protected enclosure (27 of 29) but sharply reduced sightings among frogs released into adjacent unprotected forest facing mouse and kiwi predation, though enclosure breeding succeeded, producing metamorphosed young in both 2008 and 2009. Major difficulties included balancing source-population protection against founder numbers and low survival at exposed sites. The project rates the original Boat Bay transfer Highly Successful, but rates the overall multi-site program Partially Successful given mixed results at Long Island and Zealandia's open-forest release.