CHANGE IN DIET OF STOATS FOLLOWING POISONING OF RATS IN A NEW-ZEALANDFOREST

The abundance and diet of stoats (Mustela erminea) were compared befor e and after an aerial 1080-poison operation for possums (Trichosurus v ulpecula) in a New Zealand podocarp-hardwood forest. Poisoning dramati cally reduced ship rat (Rattus rattus) abundance. Although rats were t he main prey item of stoats before the poisoning, stoat abundance was unaffected by the operation and there was a change in stoats' diet fro m rats to birds. The conservation benefits and risks of undertaking su ch operations are not clear. It is not known whether the predation ris k for any particular species of bird (or other animal) will be higher or lower with fewer rats but the same density of stoats. As large-scal e poison operations are now common in New Zealand forests, a better un derstanding of predator-prey relationships in these areas is required as soon as possible.