Increased egg infertility associated with translocating inbred takahe (Porphyrio hochstetteri) to island refuges in New Zealand

The takahe (Porphyria hochstetteri) is a highly endangered flightless rail, endemic to New Zealand. Since 1984, a total of 24 takahe have been translo cated from a small, alpine population of approximately 120 in Fiordland and successfully established on four predator-free lowland islands with introd uced pasture grasslands. However, island takahe produce fewer juveniles per egg due to hatching failure being twice as high as it is in the natural po pulation in Fiordland. A comparison among several small, inbred populations of New Zealand birds indicated those that are the result of translocations to new habitat types (takahe and kakapo Strigops habroptilus), suffered mu ch higher rates of egg infertility than birds that have remained within the ir natural habitat range. For takahe, whether breeders had been translocate d as juveniles or had been raised on the islands was a poor predictor of re productive success. The coefficient of inbreeding was high for island takah e but high infertility and low juvenile productivity were features of breed ing pairs whether parents were related or not. However, this result might b e expected if takahe were already inbred before they were translocated to t he islands. If high egg infertility is a consequence of an inbred populatio n being translocated to a new or different habitat, then poor breeding succ ess is something that managers may have to live with in the short term unti l there is local selection for better breeders. In more general terms, the results of the study have implications for the successful translocation of individuals from inbred populations. (C) 2000 Elsevier Science Ltd. All rig hts reserved.