Re-introduction of the Banks Peninsula tree weta to Quail Island, Banks Peninsula, Canterbury, New Zealand

Summary

The Banks Peninsula tree weta (Hemideina ricta), New Zealand's rarest tree weta with a naturally range-restricted distribution, was translocated to predator-cleared Quail Island in Lyttelton Harbour by Lincoln University researchers, since the island's early-stage restored habitat lacked mature trees the species normally shelters in. To compensate, roughly 50 artificial wooden weta motels with narrow entrances too small for mice were installed on trees and posts from November 2004. On 24 January 2005, 28 weta (14 males, 14 females) were collected from four source sites on eastern Banks Peninsula, kept in the same motels they were found in to reduce stress, and transported to Quail Island, where male-female pairs were typically attached to the same kanuka tree to maximize mating success; concrete blocks packed with bamboo canes were placed nearby as shelter for future juveniles. Monitoring found 12 weta present after seven months and 3 after 18 months; by four years post-release, all originally translocated adults had died of old age, but five live adults, representing a new generation bred on the island, were found in the motels. Major difficulties included distinguishing the target species from the common Canterbury tree weta by subtle anatomical features, tracking individuals whose marks were lost with each molt, and residual mouse predation risk. The project rates itself Successful, citing confirmed multi-generational persistence and the simplicity of the artificial-refuge translocation method.