Control of invasive predators improves breeding success of an endangered alpine passerine

Birds living in alpine environments are becoming increasingly impacted by human-induced threats. We investigated the impacts of introduced mammalian predators on an endangered alpine species, the New Zealand Rockwren Xenicus gilviventris, and assessed whether predator control improved its breeding success. Nest monitoring revealed that the primary cause of nest failure was predation by invasive mammals, primarily Stoats Mustela erminea and House Mice Mus musculus. Daily survival rates (DSR) decreased with nest age, and nests were at their most vulnerable to predators just prior to fledging. DSR, egg-hatching and fledgling rates were all improved by predator trapping, demonstrating the significant impacts that even low numbers of invasive predators can have on sensitive alpine and upland species.