Survival of brown kiwi exposed to 1080 poison used for control of brushtail possums in Northland, New Zealand

Abstract

All 35 radio-tagged adult brown kiwi (Apteryx mantell i) survived at least three months after being exposed to 1080 poison (sodium monofluoroacetate) during a brushtail possum (Trichosurus vulpecul a) control operation; 22 birds were exposed to 1080 in pollard baits at a loading of 0.15% w/w, and 13 birds were exposed to 1080 presented in jam baits, at a loading of 0.08% w/w. A radio-tagged juvenile was killed by a predator 2.5 months after being exposed to jam baits. In the three months after the 1080 operation, the weights of adult kiwi in the poisoned area were no different from those in neighbouring bush patches. No traces of 1080 were found in six eggs collected from the poisoned area. From subsequent captures of birds, all 35 birds are known to have survived at least six months after the operation, and 33 (94%) survived one year after exposure to 1080 baits. These results are consistent with other similar, but smaller, studies of the survival of radio-tagged kiwi exposed to 1080 poison in pollard or carrot baits.

We conclude that possum-control operations using green-dyed and cinnamon-lured pollard or jam baits laced with 1080 poison pose a very low risk to brown kiwi through accidental primary or secondary poisoning, or by starvation due to a diminished supply of large invertebrates.