Mustelids are widespread throughout Southland, but are absent from Stewart Island/Rakiura, although possible stoat sightings have been reported.

What is it?

Ferrets are the largest mustelid in New Zealand and have a creamy-yellow undercoat with legs and tail appearing darker than the body. The lighter facial region has a dark mask around the eyes and across the nose.

Stoats are smaller than ferrets and have long thin bodies, smooth pointed heads with brown fur and creamy-white underparts. They have a distinctive bushy black tipped tail.

Weasels are the smallest and least common mustelid in New Zealand and have brown fur with white underparts often broken by brown spots. They have a short brown tail which has no black tip.

What is the problem?  

Mustelids are devastating predators which pose a serious threat to the biodiversity and economy of Southland. They prey on native birds, lizards, insects, bats and freshwater fish. Mustelids also negatively impact poultry by killing hens and taking eggs. They will also target pets such as guinea pigs and pet rabbits. Ferrets are significant carriers of Bovine Tuberculosis.

How to control it

Control MethodExample
TrappingKill traps include DOC 200 or DOC 250, Fenn, Victor (modified for stoats), A24 self re-setting (weasels and stoats) and Timms (ferret trap).
PoisoningThrough secondary poisoning when mustelids feed on a 1080 target animal such as a possum or rat. For ferrets using diphacinone paste applied during summer and autumn.

For details on control methods, see our factsheet on mustelids.


Mustelids are a suppression animal on mainland Southland. They are too well established to eradicate from the mainland, so our aim is to suppress their numbers to minimise impacts on the community and the environment. Mustelids are an exclusion animal on Stewart Island/Rakiura, offshore islands and inland islands.


Any person keeping a mustelid must have it neutered. They must ensure it is kept in a securely fastened cage from which the mustelid cannot escape at any time. No person shall possess, transport to, or release any mustelid on Stewart Island/Rakiura, any offshore island or any inland island. There is no rule requiring any person to control mustelids, as this is voluntary. For a full explanation of the rules for mustelids see the Regional Pest Management Strategy.

Page reviewed: 09 May 2016 10:36am