Importance of ground weta (Hemiandrus spp.) in stoat (Mustela erminea) diet in small montane valleys and alpine grasslands

Most research into the diet of stoats in New Zealand has been in low altitude valleys such as the Eglinton and Hollyford Valleys. Yet much of New Zealand’s national parks (e.g. Fiordland National Park) consist of many small montane valleys and alpine areas. This research identified the key prey species of stoats inhabiting such small montane valleys and alpine grasslands. Stoats were collected from Department of Conservation kill-trap lines in the Murchison Mountains in Fiordland National Park over two summers (1999/ 2000 and 2000/2001) that followed heavy and moderate beech and snow tussock seed-fall events respectively. During the first summer mice were the most common prey item in stoat stomachs (68%), however in the second summer ground weta occurred most commonly (59%). These results support previous stoat research and suggest that ground weta may be an important prey species for stoats in the Murchison Mountains.