In New Zealand, mustelids do to the birds what the possums do to the trees in an environment where they have few limiting factors on their success except the availability of food. New Zealand s native plants and animals are under enormous threat from some introduced species that have accompanied human colonisation of this isolated island chain. In isolation, New Zealand s natural inhabitants had adapted to a life free of four-footed predators. The arrival of efficient mammalian predators, plus the general loss of habitat through land clearances has put many species at risk. The competition for habitat, the pressure on ground nesting birds, the overwhelming capability of the new aggressors has had a catastrophic effect on local ecosystems.
Mustelids are . . .
Slender bodied carnivorous mammals that naturally occur throughout Asia, Europe and North America. Three species were introduced into New Zealand. Ferrets are named to distinguish them from their ancestral stock, the European polecat. Although different in name, they are the same biological species. In New Zealand, ferrets traditionally have been limited to pastoral habitats, rough grassland, riverbeds, scrub-land and the fringes of nearby forests.