Mustelids

Mustelids are a diverse group of small to medium-sized carnivores distributed throughout the world. Three species occur in New Zealand, the ferret, the stoat, and the weasel.

Stoat3Mustelids were first introduced in the 1880s to control New Zealand’s growing rabbit plagues. Unfortunately they had limited effect on rabbit populations but are now the main predator of rodents and birds over the whole country

Mustelids are a major threat to the survival of New Zealand’s native birds and animals. Flightless birds (such as kiwi) and birds that nest in holes (such as kaka) are particularly vulnerable. Mustelids are a major threat to chickens being raised on lifestyle blocks and in urban backyards. They will also target pets such as guinea pigs or rabbits. Ferrets can carry bovine tuberculosis (TB) and all mustelids carry parasites and toxoplasmosis, which can cause miscarriages in sheep and illness in humans.

Mustelids are found in diverse habitats including fertile pasture, rough grassland, tussock, scrub land and the fringes of nearby forest (forest fragments) and wherever there are high numbers of rabbits.

In general mustelids are difficult to trap, and only trapping to a high standard will bring about increased survival rates of birds. Keep a watchful eye out for them and their tracks and droppings.

There are three main options for controlling mustelids on your land. For specific information in your area and to get assistance in controlling mustelids, contact your local regional council. 

Methods of control 

Trapping

For welfare performance of animal traps go to https://www.bionet.nz/control/pests-under-management/performance-traps/

Trapping is an effective tool for mustelid control, particularly where a permanent trapping grid is maintained. Because live traps require daily checking, kill traps are recommended, although no.1 leg-hold traps are often used for one-off ferret control operations over large areas. 

An excellent source of information relating to mustelid trapping in New Zealand can be found at http://www.predatortraps.com/

Poisoning

There is no poison registered for the direct control of stoats or weasels. Diphacinone poison is registered for ferret control, marketed as “Pestoff Ferret Paste”, a blended fish paste containing 0.3g/kg of diphacinone anti-coagulant poison. Apply a single 100 g (approx.) paste baits in Pestoff Tunnel Bait Stations.

Ferrets take poison baits most readily from summer through to early winter. Check and replace baits weekly, until baits stop being taken. Expect re-invasion to occur quickly and be prepared to undertake poisoning regularly.

Alternating the use of traps and poison is recommended for ongoing control programs. Poison can be readily applied inside established trap tunnels. The sister publication Vertebrate Toxic Agents – Minimum Requirements for the Safe Use and Handling of Vertebrate Toxic Agents is to be read in conjunction with these guidelines.

Some poisons require a Controlled Substance Licence. For more information about this licence and application forms, visit www.epa.govt.nz or www.business.govt.nz/worksafe. Disclaimer: Any product names mentioned above are not an endorsement nor are they a criticism of similar products not mentioned.

Fencing

Effective pest-proof fencing is a new conservation management tool. It offers a permanent solution for the protection of wildlife, and the enhancement of native forest areas, bush remnants or wetlands. Fencing offers the potential to eradicate pests from protected areas. Because of the small size of stoats and weasels, and their climbing ability, exclusion fencing is a specialised task.

Legal requirements 

For a list of legal requirements check out the legal requirements page

For more specific information on the control of mustelids check out the 'Pest Mustelids: Monitoring and Control' in the library. 

More information 

Get the tools and guidance you need for your community PF2050 project. Includes beginner tips, trap and bait profiles, how-tos and funding resources.

Disclaimer

The information on this website is intended to provide information about pests and pest management in New Zealand. We've made every effort to make sure that the information set out in this website is accurate. If you have an update to the information listed here please contact us.

Photo credit: Soumyajit Nandy. | CC