Ferret Mustela furo

About this pest

KEY CLUES

Distinctive features: Long, narrow body and short legs. Woolly fur, creamy-white to yellow, with a dark tail and black face mask.

Size: Body length, excluding tail, for males ranges between 376–580 mm while for females it ranges between 320–502mm. Males weigh about 1.3kg, while females weigh about 770g.

Droppings: Up to 70 mm long, 10 mm wide, black with twisted tapering ends.

Footprints: Five-toes on each foot, with fur between the pads. Largest footprints of the three mustelid species.

Kill signs: Puncture holes from canine teeth are sometimes obvious in prey.

Vegetation damage: Not applicable (carnivores).

Eye-shine: Green

Distribution: Present throughout the North Island and South Island, but absent from Stewart Island. Common in pastoral habitat, tussock grasslands and river valleys, but absent from forest interiors.

WHY ARE FERRETS PESTS?

Ecological impacts

Predation by ferrets has adverse effects on several native species. Ferrets aren’t as common in large tracts of forest as stoats, but their ability to kill adult kiwi has become a problem in areas where forest is more fragmented such as in Northland. On the Otago Peninsula, ferrets have been shown to reduce the breeding success of yellow-eyed penguins, and throughout New Zealand they are known to attack the burrows of seabirds, and the nests of shorebirds. Video evidence has shown ferrets to be responsible for 18% of lethal attacks on ground nesting birds in braided rivers in the Mackenzie Basin; this includes attacks on the critically endangered black stilt. Ferrets can also eat large numbers of native skinks.

Other impacts

Ferrets were introduced into New Zealand as a natural enemy of rabbits and therefore were expected to provide a benefit to the agriculture industry. Ferrets have reduced rabbit numbers in wetter lowland parts of New Zealand through predation on juveniles. However, in semi-arid areas such as Central Otago where rabbits have caused the most damage to pasture, ferrets are not able to reduce rabbit numbers. In a twist of fate, ferrets have now become a threat to New Zealand’s agriculture industry, because they are known to carry bovine tuberculosis (TB) and can transmit it to livestock.

Read more about ferrets.


Droppings

Separate

Ferret droppings are long, thin and taper towards a twist at each end. They are hard and black when dry and are often left in conspicuous positions (e.g. on top of a rock) for territorial marking. Droppings are typically 40–70 mm long and 10 mm wide. They can be curled, and will be full of feathers, fur, bones, or insect cuticle. They are difficult to distinguish from stoat or weasel droppings, but they will on average be larger. Older droppings have a paler colour.

Can be confused with:
Stoat and weasel droppings are very similar; ferret droppings tend to be longer and wider but not reliably so. Juvenile ferrets could produce droppings of the same size as adult stoats or weasels. Cat droppings are rounder in cross section, smoother and segmented.  Hedgehog droppings look more granular and are not as pointed at the ends.

Clumped

Ferret droppings can adhere to each other in a clump, though indiviudal droppings are long, thin and taper towards a twist at each end. Dropppings are hard and black when dry and are often left in conspicuous positions (e.g. on top of a rock) for territorial marking. Individual droppings are typically 40–70 mm long and 10 mm wide, and droppings will be full of feathers, fur, bones or insect cuticle. They are difficult to distinguish from stoat or weasel droppings, but they will on average be larger.  Older droppings have a paler colour.

Can be confused with:

Stoat and weasel droppings are very similar; ferret droppings tend to be longer and wider but not reliably so. Juvenile ferrets could produce droppings of the same size as adult stoats or weasels. Cat droppings are rounder in cross section, smoother and segmented.  Hedgehog droppings look more granular and are not as pointed at the ends.

Not the droppings you were looking for?

Have a look at all our droppings clues.

Footprints and Tracks

Paws and feet

Ferrets have short legs with five toes on each foot. There is fur between the pads (fleshy bits on the underside of the feet) and the claws are sharp and can’t be retracted (unlike a cat’s claws). Footprints or tracks are not readily seen in the wild except in snow, fine sand or mud. However, they can be recorded in ‘Tracking Tunnels’ which use a bait to lure animals across an ink pad and a replaceable card. Being the largest species of mustelid in New Zealand, ferrets leave the largest tracks. Approximate sizes are: forefoot 35mm long and 35mm wide, hindfoot 50mm long and 35mm wide. Ferrets’ looping, bouncing gait results in a gap of 300–500 mm between front and hind feet when running.

Can be confused with:
Ferret tracks can be confused with stoat tracks. Ferret tracks tend to be larger, but not reliably so. Occasionally there will be overlap in the size of footprints between species i.e. the footprints of very young ferrets will overlap those of large male stoats.

Dens and nests

Ferrets typically den in rabbit burrows. The previous occupants have usually provided a meal. They can also den in and under buildings, such as hay barns. As with other mustelids, individual ferrets may have several dens within their home range. Normally, ferrets stick to themselves but, occasionally, they have been observed to share dens.

Not the footprints or tracks you were looking for?

Have a look at all of our tracks.

Vegetation Damage

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Browse all types of vegetation damage.

Kill Sign

Fur, feathers or scales (vertebrate)

Ferret droppings can give kill information as they often contain remnants of feather, fur, bones and insect cuticle.

Birds

Like other mustelids, ferrets kill birds with a distinctive bite to the back of the neck. Typically, ferrets will move their prey to cover, seldom leaving prey items in the open. Sometimes puncture wounds can be found on the neck or head of birds, but these are difficult to discern from stoats and feral cats. The average inter-canine distance of a ferret is approximately 10.7 mm.

Mammals

Ferrets kill other small mammals with a distinctive bite to the back of their neck. In New Zealand, ferrets eat rabbits all year round, but can also eat mice and rats. Ferrets are not strong runners, and therefore hunt rabbits in their burrows. Ferrets use their senses to track lactating female rabbits back to burrows full of nestling young. Ferrets can create and scent-mark caches of surplus food.

Lizards and frogs

Ferrets prey on lizards and frogs, and are likely to eat them whole, leaving few remains. Lizard scales, feet and tail parts will be obvious if ferret droppings are partitioned under a microscope.

Can be confused with:

Predation by cats, stoats and weasels. Remember, too, that animal remains might have been scavenged.

Insects or snails (invertebrate)

Ferrets prey on invertebrates, and are likely to eat them whole, leaving few prey remains. When droppings are partitioned under a microscope, the cuticles, abdomens, legs and mandibles of invertebrates will be obvious if present.

Eggs

Ferrets are poor climbers and therefore only prey on eggs of bird species that nest on the ground or in burrows. Ferret predation of eggs may be similar to predation by stoats with the ferret piercing the egg with its canine teeth. Eventually the ferret will create a large hole and remove the egg contents, and may break the egg shell into several pieces.

Can be confused with:
Stoat or feral cat predation of eggs. Remember, too, that egg remains might have been scavenged.

Not the kill signs you were looking for?

Have a look at all our kill signs.

Other Clues

Smell

Ferrets have anal glands under the tail which produce a strong musk smell.

Can be confused with:
Stoats also have anal sacs and are capable of producing a musk smell.

Sound

When frightened, ferrets can make a high-pitched barking noise. Submissive ferrets sometimes squeal. They can also hiss and chatter in confrontational situations.
Can be confused with:
Many ferret vocalisations sound similar to those of stoats.

Body covering

Ferrets have a short, woolly undercoat that is creamy-white to yellow, covered with dark guard hairs. The tail is uniformly dark and the face has a black mask.

Eye shine

Green.

Can be confused with:
Stoat eye-shine.

Distribution

Ferrets are widespread in both the North Island and South Island of New Zealand, but have only recently spread to some regions e.g. Golden Bay and Northland. Ferrets are not found on Stewart Island or other offshore islands. They are common in grassland and pastoral land but tend to be absent from large tracts of forest, although they may inhabit the forest periphery.

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MORE ABOUT FERRETS

Origin

The feral ferret is the domesticated form of the European polecat (Mustela putorius) and is generally considered a subspecies (feral means in a wild state after a period of domestication). Ferret is Latin for ‘little thief’ and it is believed domestication may have begun in Roman times, with ferrets being used to hunt rabbits (ferreting). Ferrets were introduced into New Zealand to control rabbits. The earliest recorded release was in 1879. Ferrets were also previously farmed for fur (fitch farming), but when the fur market collapsed fitches were sometimes released into the surrounding area.

Description

The ferret is the largest of the three species of mustelid in New Zealand, but still has the long, narrow body and short legs typical of mustelids. Its ears are flattened against the head and it has a number of bristles on its face that it uses when hunting in burrows. Its coat is more woolly than that of the short-haired stoat and weasel and the undercoat can be creamy-white or yellow, but hairs on the shoulders, flanks and legs can be dark. The tail is also usually covered in dark hair. One of the most tell-tale features of a ferret is the black fur on its face that looks like a mask.

Size and weight

Adult males can weigh 1–1.3kg, while adult females are smaller and weigh 500–770g. Body length, excluding the tail, ranges from 376–580mm for males and 320–502mm for females. The tail of the male is approximately 150–160mm long, while for the female it is approximately 120–140mm long.

Behaviour

Ferrets are usually nocturnal, but can occasionally be seen above ground during the day. Sometimes during the breeding season males have wounds on their shoulders or throats, because they have been fighting over females. Ferrets are usually solitary, although they have sometimes been observed to share dens. Unlike the stoat and weasel, the ferret is not able to climb trees very well.

Diet

Ferrets mostly commonly eat rabbits or hares. However, they will eat a wide range of other prey when the opportunity arises, or when hares are not present, including birds, lizards, invertebrates (weta and beetles), rats and mice.

Habitat

Ferrets are most common in pastoral habitats. They may occupy forest peripheries and native tussock grasslands, but they tend to be absent from forest interiors. They can also occupy coastal dune lands and occur on braided rivers, although they mainly keep to grassy areas on the edge of the rivers.

Distribution

See distribution clue.

Other

New Zealand has the largest known population of feral ferrets in the world.

How to get rid of ferrets

Meaningful control of ferrets requires extensive trap networks over large areas. The DOC 250 is the recommended trap for controlling ferrets and has passed National Animal Welfare Advisory Committee (NAWAC) guidelines for humaneness. DOC 250 traps must be used in a trapping box such as a DOC 250 box to insure that non-target species such as kiwi, kea, weka or penguins are not caught in the trap.

For more information and guidance on setting up ferret control, contact your local DOC office and see Next Steps.


FIND MORE INFORMATION IN:

Clapperton, B.K., & Byrom, A. (2005). Feral ferret. In King, C.M., (Ed.), The handbook of New Zealand mammals (pp. 294-308). Auckland, New Zealand: Oxford University Press.