Transfer of Hamilton's frog, Leiopelma hamiltoni, to a newly created habitat on Stephens Island, New Zealand

On Stephens Island in Cook Strait, the endangered Hamilton's frog, Leiopelma hamiltoni, is confined to one small, severely modified habitat (600 m(2) rock-tumble). This habitat has become susceptible to climatic extremes through loss of vegetation cover. To enhance the population, estimated to be around 170 frogs, a new habitat was created between May and October 1991 in a nearby forest remnant 40 m from the rock-tumble, by excavation of pits and backfilling these with rocks. A predator-proof fence was built around the new habitat to exclude tuatara, Sphenodon punctatus, and the area was "seeded" with invertebrate prey. Twelve adult frogs were transferred to the site in May 1992. Twenty-seven recaptures of seven of the transferred frogs have been recorded to June 1993. Recaptured frogs showed variable changes of weight since transfer, with a mean increase of 23% (range = 12% loss to 55% gain); only one showed a detectable increase in snout-vent length. Breeding at the new site has yet to be confirmed.