Stoat

What does it look like?

You can easily distinguish a stoat from a weasel by its black-tipped tail.

Stoats grow to around 34–40 centimetres long, including their tail, and are long and slender (about half the size of a rabbit). Stoats usually have a chestnut‑brown coat with a cream-coloured belly and a distinctive black tip on the tail. In colder climates, their fur can turn white in winter.

Stoats can live in almost any habitat where there’s food available. In New Zealand, they’re found at all altitudes and in many environments, including native and exotic forests, scrub, sand dunes, pasture and areas close to people. They are most common in forests rather than open country.

One of the easiest signs that mustelids are present is their droppings (scats). These are long, thin and often twisted at both ends. They usually contain fur, feathers and small bone fragments. Scats are often left in open places and turn hard and black when dry. Mustelids also leave a strong smelling, oily yellow substance called musk on their scats, which helps mark their territory and signal to other mustelids in the area.

Why is it a problem?

All mustelids can be devastating to native bird life and other fauna. They have very good hearing and a strong sense of smell.

Stoats are extremely fierce and will kill more prey than they need for food if they have the opportunity. They will also attack prey much larger than themselves. It’s estimated that 60 percent of North Island brown kiwi chicks born each year are killed by stoats. Stoats usually eat the flesh from the neck and head area of their prey. Often only the head will be consumed, with a preference for feeding on the blood, particularly with chickens.

Stoats hunt during the day or at night and can cover large distances. The main prey of stoats are rodents, birds and their eggs, rabbits, hares, possums, and invertebrates (particularly weta). Lizards, freshwater crayfish, carrion, hedgehogs, and fish are also taken.

Stoats produce a single litter of up to 12 kits each year. Female stoats have the unusual ability to carry fertilised eggs inside their bodies from mating in summer until the following spring. Young stoats are adults at two months, and female kittens can be mated while still in the nest. They can travel large distances, even crossing water. Most juvenile stoats live less than one year but adult mortality is lower, and they may reach six to eight years of age.

Control methods

Traps

The Department of Conservation (DOC) series of traps, the DOC 150, 200 and 250, are used nationally for predator control. The DOC 150 and 200 are suitable for catching stoats and weasels, while the larger DOC 250 can kill any mustelids. These traps are easy to use but you need to be strong to set them. Always follow trap manufacturer instructions when using traps and consider using a setting tool for safety.

Good places for traps are areas where stoats would be travelling or hunting for rabbits and other prey (near cover, along streams, offal holes, pathways, tracks and fence lines, tree lanes and forest margins). If you don’t catch them after some time, then experiment with different bait and/or locations. You can modify the trap with a plate ramp and/or duct tape on the metal plate (metal is a non-natural (cold) surface and is believed to create aversion behaviour in some individuals).

If you are trapping over a large area, then set the traps about 100-200m apart. Put a number on each trap and keep a record of how many have been set, when and where.
Bait and 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 bait deteriorates faster, food sources dwindle and catch rates can go up. Wear gloves when handling the bait and setting traps as mustelids can detect and be put off by human scent.

All DOC series traps are also capable of killing rats and hedgehogs. If you have cats then use eggs as bait and avoid meat or buy a Weka link extension for the trap which also works to keep cats out. For more information on how to use DOC traps, visit https://predatorfreenz.org/ , www.doc.govt.nz, search “backyard trapping” or contact the Regional Council for solutions to issues encountered.

Bait/Lure

The best lure for mustelids is fresh or salted rabbit. Eggs or fish flavoured cat food work well. There are commercial long-life baits on the market. Raw fat is very attractive over winter. Spray on lures are also effective. A piece of bait or fish can be dragged around on a piece of string to make a scent trail leading to the trap.

Shot rabbits make good mustelid bait and can be frozen until you have enough to salt. Partially defrost rabbits (there is less mess when butchering). Put the salted bait on top of two or three nails (or hang) inside your traps to help it last and to aid scent dispersal. The bait should last around three weeks depending on the weather and the shade on your trap site.

Dispose of all used bait carefully, either bury or remove from the area. You must not leave used bait in the field where stoats may find it, taste it and be put off going into traps.

Use scent and by-kill to your advantage. Utilise a freshly killed stoat or weasel by rubbing its anus over the trap. This will create a smell “neon sign” irresistible for other stoats, increasing curiosity and likelihood of successive kills. Using sex-drive can also solve the issue of abundant food sources in the environment reducing the attraction of carrion as bait. Additionally, using stoat, weasel scent or freshly killed rats will lure these and other predators which are looking for these animals as prey.

More information

See also: 

Weasel

Ferret

 

Related links

• Stoats – Animal Pests (DOC NZ)
• Predator Free 2050 Trapping Guide (PDF) – DOC NZ
• Where to Buy Traps and Equipment – Predator Free NZ
• Hawke’s Bay Regional Pest Management Plan 2018–2038 (PDF)
• Fine-Tuning Your Predator Control – Webinar (Predator Free NZ)
• How Do I Identify My Pest? – BioNet NZ
• DOC 200 Predator Trap Instructions (PDF)