- Department of Conservation, Level 3, Grand Central, 161 Cashel Street, Christchurch 8011, New Zealand
- Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, British Columbia, Canada
- University of St Andrews, Buchanan Gardens, St. Andrews, KY16 9LX, United Kingdom
New Zealand’s native birds are particularly vulnerable to predation from introduced mammals, especially rodents and mustelids. The prolific seeding of trees during mast years triggers rodent irruptions, and the subsequent increase in mustelids can have devastating effects on native bird populations. Waitutu Forest, in Fiordland, New Zealand, has experienced declines in many of its bird populations and has been subject to pest management since 2008 to reverse these trends. A monitoring programme was established to determine the success of this management. Several peaks in seed-rain indicated partial or full mast events, which appeared to drive increases in rodent and mustelid populations. However, with a few exceptions, indices of abundance for mustelids and rats were consistently low (< 10% tracking) for at least 12 months following 1080 operations, indicating that aerial application of 1080 was effective at suppressing these predators. Five indigenous bird species, all with high levels of endemism, responded positively to pest management. Conversely, six bird species (three indigenous, three introduced) showed population declines, potentially the result of inter-specific competition from those species that benefitted most from pest management. The remaining nine bird species monitored in this study showed no significant increase or decrease during the study. There was considerable spatial variation in relative abundances of most bird species. The pattern was different between species, suggesting that variations were due to differences in site characteristics or linked to inter-specific competition. Despite the absence of a non-treatment site for comparison, this study has provided useful time-based insights into the population trends of birds at the study sites. It is recommended that the management and associated monitoring continue, to further increase our understanding of bird population dynamics in response to pest management and to monitor the impacts of future environmental changes.