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Stoats, weasels and ferrets (mustelids)

Stoats, weasels and ferrets (mustelids)

Updated 17 June 2021 4:29pm


Copyright Dept of Conservation

Why are stoats, weasels, and ferrets a problem?

These three members of the mustelid family are a major threat to our region's biodiversity. They continue to have a devastating effect on New Zealand's native animals and impact our farming industry. Mustelids eat:

  • Native birds, chicks, and eggs, including  kiwi
  • Native lizards and invertebrates like skinks and weta
  • Domestic animals such as chickens, guinea pigs, and rabbits

Ferrets may carry Bovine Tb, which can infect cattle and deer herds.

Spot a mustelid? Here's what you can do...

About mustelids

Mustelids are relentless hunters, described as having only two reasons for living - to eat and to breed. They can hunt day and night, climb trees, have a territory of over a kilometre, and swim for a few kilometres. The mustelids in New Zealand are:

  • Stoats (Mustela erminea) are the most common mustelid in the Wellington Region. They are 35-40 cm long, have a brown/black coat with a pale belly and throat, and a bushy black-tipped tail

They may look cute, but they are 'public enemy number one' for New Zealand birds

  • Weasels (Mustela nivalis) are the smallest of the mustelids. They are 20-25 cm long, have a deep brown to light tan coat, with a light coloured underbelly and throat, and a short brown tapering tail
  • Ferrets (Mustela furo) are the largest of the mustelids. They are 48-55 cm long, have a creamy yellow coat with long black hairs, a tail and legs darker than the body, and a dark 'bandit' mask around the eyes and nose

These pests were introduced into New Zealand in the 19th Century in an attempt to control the rabbit population. The potential impact on the native bird species was known, but agriculture took precedence over the environment at the time. 

Signs to look for

Mustelid droppings are long thin and strongly scented, often with a twist at each end. They are usually left in open places such as the middle of tracks or clearings. 

They may leave dead prey with chew marks on their head or neck if they are disturbed. 

If there are high numbers of rabbits, rats, chickens, or waterbirds then there may also be stoats. 

 What can I do?

The most effective way to control mustelids is regular and ongoing trapping. 

  1. Get trapping: Buy traps online or contact us. Download this quick trapping guide from Predator Free New Zealand and watch this video on how to set up a DOC 200 trap

  2. Location, location, location: Good places for traps are along pathways, tracks and fence lines, near natural or artificial cover, waterways or food sources. If you are trapping over a large area then set the traps about 100m apart. Put a number on each trap and keep a record of how many have been set, when and where

  3. Bait it: The best bait is something fresh such as; eggs, cat food, fresh fish, chicken, mice, rats, possums and rabbits

  4. Check it & don’t forget it: Check the traps at least once a month and change the bait. Remove and dispose of old bait away from the trap. Check traps more often in late summer and autumn as food sources dwindle and catch rates can go up


  • If you have cats then use eggs as bait and avoid meat. Buy a weka link extension for the trap. This also works to keep cats out.
  • Wear gloves when handling the bait and setting traps as mustelids can detect, and be put off by, human scent.
  • If you don’t catch them immediately then experiment with different bait and locations. They are very suspicious of baits and traps.

If you spot a mustelid in a park or forest then note the area, take a photo if you can, and contact us on 0800 496 734 or email

For more information

More about trapping

Department of Conservation Predator Free 2050

Bionet - information about pests and disease in New Zealand