What does it look like?
Ferrets, Stoats and Weasels all belong to a group of animals known as ‘Mustelids’. Ferrets are the largest of the three, measuring about 48-56 cm long, including the tail. Their colours vary but they are usually dark brown or blackish with a creamy under fur, but they can appear almost white/creamy white. The tail is uniformly dark, and the face is pale with a dark mask over the eyes. Adult males are generally larger than the females.
Ferrets are generally absent or in low numbers in areas of high rainfall, or deep within forested areas where there are few rabbits. It was originally thought that ferrets were limited only to open country like pasture, scrubland, coastal areas and in the fringes of forests. However, research has found ferrets within some forests, placing added pressure on already threatened native bird populations. Mustelids usually eat the flesh from the neck and head area of their prey. Often only the head will be consumed, particularly with chickens.
The easiest way to determine whether mustelids are present in an area is to look for long and thin scats, often with a characteristic tapering twist at each end. These droppings are filled with fur, feathers and bone fragments. Scats are often found out in the open, such as in the middle of a track. They are hard and black when dry. Mustelids secrete a thick, oily yellow, powerful smelling fluid called musk onto their scats. This acts as a sign to other mustelids in the area.
Why is it a problem?
Mustelids can be devastating to native bird life and other fauna. They have very good hearing and a strong sense of smell. Ferrets also can carry Bovine TB disease.
Ferrets hunt mostly at night. Their main prey are rabbits and hares, but they also feed on native birds, especially ground-nesting birds, lizards, frogs, and large native invertebrates like Weta. They are good climbers and can steal eggs and chicks from nests in trees. Ferrets are one of the few predators able to kill an adult kiwi. They will also kill little blue penguins, possums, eels, hedgehogs, and other small mammals.
Ferrets are successful breeders, producing between four and eight kittens per litter and one or two litters each year. Within three months of being born, a young ferret can move out into its own territory. There is high mortality in the first year, and their average lifespan in the wild may be four to five years.
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 of the mustelids. These traps are easy to use but you need to be strong to set the larger traps. Always follow trap manufacturer instructions when using traps and consider using a setting tool for safety.
Good places for traps are areas where ferrets 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 are trapping over a large area, 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.
Shooting
You can often come across mustelids, particularly ferrets, while spotlighting rabbits and possums. They can certainly be shot, although shooting alone is not an effective control measure. Ferrets have green eyes, similar to a cat in a spotlight, except for albinos, which have pink eyes.
Poisoning
Pestoff Ferret paste is the only current registered toxin used for the control of ferrets. It contains an anti-coagulant poison mixed with a fish paste. Poison baiting is best carried out over the summer-autumn period when ferrets are dispersing and most active.
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. If you don’t catch them immediately then experiment with different bait and locations. Ferrets are very suspicious of baits and traps. You can modify the trap to reduce aversion by applying duct tape over the metal plate (metal is a non-natural (cold) surface and this tactile sensitivity is believed to discourage some individuals from interaction).
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 musk scent to your advantage. Utilise a freshly killed ferret by rubbing its anus over the trap. This will create a smell “neon sign” irresistible for other ferrets, 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.
Note that the smell of top predators such as ferrets and cats can put off animals lower down the food chain.
More information
See also:
Weasel
Related links
- Ferrets – Diphacinone Paste Label (PDF) – PestDSS / Landcare Research
- Predator Free 2050 Trapping Guide (PDF) – DOC NZ
- Where to Buy Predator Control 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
Management Programme
Site-led Pest Programme
Pests listed under the site-led programmes, and most of the other pests included in the RPMP, are capable of damaging habitats and important ecosystem processes, or competing with indigenous species for food, or prey directly on native species. Pest management, habitat protection (e.g. via fencing) and habitat restoration/creation (e.g. via planting) are key management measures in halting biodiversity decline in Hawkes Bay. A site-led management programme significantly assists with the delivery of each of these goals.
More informationSustained Control Programme
Sustained Control exists to hold well-established pests at an acceptable maximum. However, the costs of management and control grow in-step with the size of the invasive population. Because cost:benefit returns can fall to 1:5 or less, most of this work is focused on specific sites of high ecological value. While the spread of these pests between neighbouring properties remains the predominant risk, in some cases control within properties is still sought and warranted. A sustained control programme will hold populations to maximum acceptable limits over the period of the RPMP.
More informationRules
Plan Rule 16
All occupiers within a Predator Control Area shall maintain ferrets, stoats, weasels, and feral cats in accordance with the Hawke's Bay Regional Predator Control Technical Protocol (PN 4970)
More informationSections 52 and 53 of the Biosecurity Act (1993)
No person shall knowingly communicate, cause to be communicated, release, or cause to be released, or otherwise spread any pest or unwanted organism, in accordance with Sections 52 and 53 of the Biosecurity Act 1993
More informationTaxonomies
FamilyMustelidae
TypeAnimals
GroupMammal
HabitatLand
Management ProgrammeSite-led Pest ProgrammeSustained Control Programme
RulesPlan Rule 16Sections 52 and 53 of the Biosecurity Act (1993)
