Abstract
While there have been significant conservation successes through restoration of island biodiversityfollowing the eradication of invasive predators, a major challenge remains to reintroduce native species withinlarger mainland systems that support suites of introduced mammalian predators. Strategies to enhance establish-ment and persistence of reintroduced populations include pre-release management to reduce post-release disper-sal, and habitat restoration such as predator control at release sites. Evaluation of such strategies criticallyrequires strategic and intensive post-release monitoring to identify drivers of success or the specific causes of fail-ures. The buff weka (Gallirallus australis hectori), aflightless rail, was reintroduced to an unfenced mainlandisland on New Zealand’s South. Past reintroductions on the mainland have all failed, but lack of post-releasemonitoring has meant the exact cause and timing of failures is unknown. We investigate the ability of buff wekato establish a mainland population in conjunction with high intensity predator control. Nineteen buff weka (15males, 4 females) were transferred from predator-free islands in Lake Wakatipu, South Island, to Motatapu Sta-tion and held in a pre-release enclosure for 6 weeks. Using a combination of very high frequency (VHF) andGlobal Positioning System (GPS) telemetry, released birds were monitored every 2 days for 4 months post-release. Following release, no buff weka dispersed off Motatapu Station. Survival, however, was low and by theend of the study, 12 (63%) buff weka had been predated by introduced mustelids, ferrets (Mustela furo) andstoats (Mustela erminea). The lack of dispersal by buff weka suggests the presence of favourable resources onMotatapu Station. However, the low survival rate indicates that the predator-trapping network was insufficient tosuppress predator numbers to a level low enough for buff weka population persistence.