Recovery and range expansion of the once critically endangered Mercury Islands tusked wētā (Motuweta isolata) on Ohinau Island, New Zealand, 16-years post-translocation

Facing the possibility of extinction, three Mercury Island tusked wētā ( Motuweta isolata ), one male and two females, were translocated in 1998 from Ātiu/Middle Island into captivity to initiate a captive rearing program. Over a period of nine years, their offspring were translocated to multiple islands off the Coromandel Peninsula, Aotearoa/New Zealand. Following the release of M. isolata onto Ohinau Island in 2007, surveys during the first five years post-release showed a limited range expansion of approximately 100 m from the release site, putting the longevity of the translocated population into question. Here, we report on the now island-wide range expansion of translocated M. isolata on Ohinau Island recorded during annual seabird monitoring trips to the island from 2016 to 2023 (9 to 16 years post-translocation). We also document the scavenging of seabird carcasses as a food source in this species. Additional follow-up surveys across the rest of the Mercury Islands and standardized surveys on Ohinau Island are warranted to quantitatively determine the long-term translocation success and ultimately the recovery of the species from near extinction.