Impacts of aerial 1080 predator control on nest success and adult survival of South Island robins

Little is known about the impact of aerial 1080 control on nesting success and abundance of birds. The South Island (SI) robin (Petroica australis) is vulnerable to predation by exotic mammals, with declining populations on the east coast of the South Island of New Zealand. We document the effect of an aerial 1080 operation carried out in 2011 on the relative abundance of brushtail possums (Trichosurus vulpecula), rats (Rattus spp.), house mice (Mus musculus), and on SI robin nest success, comparing a site receiving aerial 1080 (Silver Peaks) to a non-treated site (Silverstream) in the Dunedin region. Although control reduced predator numbers, the relative abundance of house mice had recovered to pre-control levels after five months, as had rats after 12 months and brushtail possums after 15 months. There were no significant differences in SI robin nest success and nest survival over time between the treated and untreated sites, although negative relationships between nesting success and possum and rat abundance were observed.