Secondary poisoning of stoats after an aerial 1080 poison operation in Pureora Forest, New Zealand

Stoats were monitored by three methods through an aerial 1080 poisoning operation at Waimanoa, Pureora Forest in August 1997. Tracking rates and number of live captures were used as indices of abundance, and radio-transmitters were used to follow individual animals. All 13 stoats with radio-transmitters within the poisoned area died between 2-18 days after the operation. No mustelids were tracked or live-trapped after the operation for three months. Of the radio-tracked stoats that died, rat remains occurred in 67%, passerine birds in 17%, cave weta in 17% and possum in 8%. Residues of 1080 were found in 12 of the 13 dead stoats. Our findings have important implications for the management of threatened species. Stoats are known to be a major factor in the continuing decline of some native birds. Previously, the potential of secondary poisoning to control stoats land other predators) in New Zealand had focused on the use of anticoagulants, as these compounds persist and can accumulate in predators over a longer period. However, our results suggest that secondary poisoning with an acute toxin can also be highly efficient. This may also have greater public acceptability.