Mustelids are a large group of small to medium-sized carnivores that originate from Europe. Three species of Mustelid: the stoat, the weasel and the ferret, were introduced into New Zealand in the late 1880s to control rabbits. Mustelids will prey on birds, feral mice, rabbits, hares, rats, possums and insects. They are all active hunters and have a detrimental effect on our indigenous fauna. They are also a recognised vector in the spread of the disease Bovine Tuberculosis to domestic livestock.
Populations of mustelids exist in the North and South Island. Population levels vary depending on habitat from low to high. Mustelids are found throughout Marlborough. Ferret populations are generally highest in rabbit-prone areas while weasels and stoat populations are generally highest in areas of indigenous bush and scrub.