Modern aerial 1080 (sodium monofluoroacetate) operations are effective in reducing population densities of possums, rats and stoats, thereby reducing predation pressure on birds. Debate regarding 1080 use, however, continues to centre on potential non-target effects, with some groups claiming that birds are killed in large numbers such that forests “fall silent”. We investigated these claims by recording birdsong for 5–8 weeks before and after three separate 1080 operations in the Aorangi and Remutaka Ranges of the lower North Island, New Zealand.
We used a long-term replicated before-after control-impact (BACI) sampling design to monitor the effect of aerial 1080 possum-control operations on common forest bird populations. Paired treatment and non- treatment sites in the Rolleston Range (East Coast, South Island) and Alexander Range (West Coast, South Island) were monitored once before 1080 treatment during winter 2012 and for three successive summers afterwards. Mammals (possums Trichosurus vulpecula, rats Rattus spp.
Rats were eradicated from Lady Alice Island (Northland, New Zealand) in October 1994, using aerially applied cereal-based bait containing brodifacoum. To determine the fate and non- target impact of brodifacoum, streams, soil, invertebrates, and birds were monitored for 7 months after the baits were applied. No brodifacoum was detected in any of the stream or soil samples. Brodifacoum was detected in cave weta found on baits, and in morepork and red-crowned parakeet liver tissue. Significant contamination of water and soil is unlikely after a single aerial application of brodifacoum baits.