Mustela nivalis vulgar

Threats Status

Unwanted Organism

Common Name(s)





Weasels can be found in any habitat with thick ground cover, including forest (native and exotic) and urban habitats. They are carnivorous and generally little is known about their prey preferences (mice and rabbits, birds, geckos, lizards and skinks and weta are thought to be a main part of their diet). They are agile climbers and good swimmers.


Weasels are the smallest and least common mustelid in New Zealand. Males grow up to about 20 cm. Their fur is brown with white under parts, often broken by brown spots. Their tails are short, brown and tapering.

Similar Species

Stoats may be mistaken for the other two species of Mustelidae in NZ: Ferret (Mustela furo) and Stoat (Mustela erminea)

Threat To Plants

Prey on birds, mice, lizards and insects may also have secondary effects on the vegetation due to changes in ecosystem processes.


Patchily over both of the North and South Island but are generally absent from any other islands (except Maud Island where one individual was recorded in 2003).


Weight: 60g (female), 130g (male) ; head to body length: 17-24cm

Year Introduced

1885 (various locations)

Reason For Introduction

Biological Control of rodents

Colonisation History

First introduced to New Zealand together with stoats, but in far higher numbers (592 weasels compared to 224 stoats between the years1885-86). In 1885 weasel were released at Lake Wanaka (183), at Lake Wakatipu (28) and Waiau River (15). Further, in 1886, individuals were introduced to Wilkin, Makaroro and Waitaki rivers and Lake Ohau (126); Marlborough and Wairarapa (116); and in the Orongorongo Valley (167). They then spread rapidly and in large numbers over both of the main islands (in places even faster than the migration of rabbits), however numbers and distribution declined just as rapidly within 1900-1925.