Species
Stoat (Mustela erminea)
The stoat is one of the most widespread of all living species of mammal. Like the weasel, the stoat occupies a wide range of habitats in all northern hemisphere countries, from Ireland through Europe and Russia to Canada and the northwestern US. It has also been introduced to various islands in the hope that it will control populations of pest rodents. Both weasels (Mustela nivalis) and stoats (Mustela erminea) were deliberately introduced into New Zealand from Britain during the 1880s to control rabbits, which were becoming a serious agricultural pest. Mustelids continued to enjoy legal protection in New Zealand until 1936. The stoat is now much more common and widespread than the weasel. Because they are small, secretive and fast moving, they are difficult to observe in the wild.
The smaller forms of the stoat in the far north are, like the common weasels, specialist predators of small rodents, but the larger ones living in warmer climates are also big enough to catch rabbits and game birds . Like the weasel, the stoat probably evolved in the far north during the glacial ages, and became well adapted to hunting voles and lemmings under snow, but it is not confined to this role. It is active any time of the day or night, but rarely seen, even though it is among the more common and widespread of the native carnivores of the northern hemisphere. In the nineteenth and early twentieth centuries, winter trapping for ermine was an important part of the fur trade, and Russian scientists did the earliest research on the population biology of stoats.
Stoats are the most significant predator of several of New Zealand’s native bird species. They are considered to be responsible for the extinction of the kakapo from the Mainland and the probable extinction of the South Island kokako. Their impact on threatened and endangered species is of particular concern.
Predation by stoats are is also an important factor contributing to the continuing decline of mainland kiwi populations.
Their secretive nature and complex population dynamics make stoat control difficult. Most current methods are expensive and labor intensive and include kill-traps, baiting and poisoning, exclusion fencing and the use of dogs to detect stoat dens.
NZ Department of Conservation, Ferrets, Stoats and Weasels (Mustelids)
