New Zealand Journal of Ecology (1992) 16(2): 137- 140

Change in Diet of Stoats Following Poisoning of Rats in a New- Zealand Forest

Research Article
E. Murphy  
P. Bradfield  
  1. Department of Conservation, Private Bag 68908, Newton, Auckland, New Zealand
  2. Department of Conservation, Te Kuiti Field Centre, P.O. Box 38, Te Kuiti, New Zealand

The abundance and diet of stoats (Mustela erminea) were compared before and after an aerial 1080-poison operation for possums (Trichosurus vulpecula) in a New Zealand podocarp- hardwood forest. Poisoning dramatically reduced ship rat (Rattus rattus) abundance. Although rats were the main prey item of stoats before the poisoning, stoat abundance was unaffected by the operation and there was a change in stoats' diet from rats to birds. The conservation benefits and risks of undertaking such operations are not clear. It is not known whether the predation risk 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-scale poison operations are now common in New Zealand forests, a better understanding of predator-prey relationships in these areas is required as soon as possible.