Introduction
The ferret (Mustela putorius furo) is the domesticated form of the wild European ferret or polecat (M. putorius). It is often considered as a subspecies (and furo added to the scientific name) because it has been domesticated for hundreds of years. However, genetically the domestic and wild ferret are identical and are therefore treated as one species. The ferret is not native to Australia but is kept here as a pet. It has potential to establish populations in Australia and become a pest.
Description
The ferret has a long, narrow body from 20-46cm in length, a tail from 7-14cm long, and short legs. It generally has a dark brown to black body with pale yellow underfur and longer, black-tipped guard hairs. The tail is black and looks bushy. The face is greyish-white with dark areas, giving the face a masked appearance, but this can be absent in some pet animals. The brownish colours are referred to as ‘sable’ and are the most common; other less common colours include silver, chocolate and white (with dark or red eyes). Immature ferrets look similar to adults.
Mistaken identity
Ferrets are not usually mistaken for native animals, but very occasionally this does happen. Native species that could be confused with ferrets include:
- Common brushtail possum (occurs throughout Australia).
- Brown bandicoots (two species that occur in northern, north-eastern and southern Australia including Tasmania).
- Quolls (four species, each with separate distributions in northern, south-western, and eastern Australia including Tasmania).
Distribution
The natural range of the wild ferret is Western Europe as far east as the Ural Mountains in west central Russia.
Introduced populations occur in many places in Europe. These have resulted from the deliberate release of wild ferrets to areas outside their natural range and the escape or release of pet ferrets. Feral populations occur in Russia, Sardinia, Sicily, Morocco and Britain, as well as on the islands of Mull, Hebrides, Arran and Bute (off the coast of Scotland), the Isle of Mann (Irish Sea) and the Isle of Anglesey (off the coast of North Wales).
The ferret was purposely introduced to Australia and New Zealand in the late 1880s. It is now a widespread, established pest in New Zealand, but it has so far apparently failed to establish permanent populations in Australia. However, reports of ferrets living in the wild occur from time to time in southern Australia, mainly in Western Australia and Tasmania.
Habitat
The ferret lives in open forests, grasslands and bushland. Modified habitats are also used including areas near human settlements and on agricultural land. It can also live in coastal areas (such as sea cliffs and sand dunes), around rubbish tips and along river banks.
Reproduction, food and behaviour
The ferret breeds once a year. Litters can contain up to 12 young but three to seven is more usual. Young ferrets (called kits) become independent when about three months old. Den sites are located under cover in crevices, hollow logs and burrows of other animals, especially rabbits. In New Zealand, dens have been found in outlying farm buildings.
The ferret is a carnivore that preys on small mammals such as rabbits, rats, mice and possums. It will hunt for birds, particularly those that nest on the ground or in burrows like some seabirds and flightless birds. It preys on reptiles, frogs and invertebrates. Eggs and carrion are also readily consumed.
Although the wild ferret is a nocturnal animal, it can occasionally be seen during the day. When it runs it arches its back and looks very supple or sinuous in appearance, but it walks with a straight body, sniffing the ground repeatedly for scent.
Male and female ferrets have separate home ranges that overlap. When food is scarce, home range sizes increase. Though usually solitary, pairs are sometimes seen foraging together and sharing dens.
In the wild ferrets live for about four to six years, but in captivity they can live up to 14 years.
Damage by the ferret
In its natural range the ferret is a minor pest of agriculture, causing damage to poultry production by preying on chickens and eggs.
Transmission of the disease bovine tuberculosis (Tb) to domestic stock is a serious threat to agriculture in New Zealand. The ferret is a Tb carrier and can infect stock through direct contact. The environment can also be contaminated with Tb-infected ferret faeces and urine that stock come into contact with while grazing.
The ferret is considered a moderate environmental pest, particularly in New Zealand, where vulnerable birds such as the weka, kiwi, kakapo, kea and laughing owl (now extinct) all declined in numbers after the ferret became established in the wild. Populations of black stilt and royal albatross (both endangered) were also adversely affected when their chicks were killed by the ferret.
The ferret can inflict painful bites on people and cause injury requiring medical treatment. Infants and small children are particularly at risk from facial bites.
Control programs are carried out in New Zealand to reduce populations of the ferret, and its destructive relatives the stoat and weasel. A variety of methods are used including trapping with a range of trap types, baits and detector dogs. Biological control methods are also being investigated for use in the future.
Potential to be a pest in Australia
The ferret is rated as being highly likely to establish wild populations in Australia and become a pest of agriculture, the environment and public amenity.
A scientific risk assessment conducted by the Department of Primary Industries and Regional Development, Western Australia and endorsed by the national Invasive Plants and Animals Committee indicates that the ferret poses an extreme threat (the highest of four categories) to Australia. Part of the assessment showed that the climates of the ferret’s overseas range and Australia are very similar.
It is therefore important that ferrets do not establish in the wild in Australia and that new genetic stock from overseas is not permitted to enter the country.
The ferret has the potential to establish small populations in the wild here that could go undetected for decades before increasing rapidly when favourable conditions occur. Successful populations could arise if any adaptation to current environmental conditions occurred, or as a result of the arrival of new genetic stock that allowed ferrets to thrive under a wider range of conditions in the wild.
The ferret is an aggressive predator that could threaten biodiversity in Australia, with a wide range of Australian native birds, mammals, marsupials, reptiles and frogs potentially at risk. Ground-nesting birds could be under threat from direct predation on their eggs and chicks, while small marsupials could be ideal prey. The ferret could also affect backyard and commercial poultry production by taking chickens and eggs.
Ferrets in the wild
Many ferrets are kept as pets in Australia and although many owners keep them leashed to avoid escape when the animals are outside their cages or on excursions, accidental release can occur. Some ferrets are still used to hunt rabbits, a practice that results in their escape into the wild. Unwanted ferrets are also intentionally released by irresponsible owners.
Ferrets make demanding pets. They must be kept indoors or in escape-proof enclosures, have a strong odour (particularly unsterilized males) and can give painful bites. They also have little monetary value because they are commonly available.
All these factors may contribute to ferrets escaping or being released into the wild, with some states and territories carrying out control programs to remove them. Some ferret societies in Australia offer a rescue service for unwanted or dumped ferrets and advocate responsible ownership.
Ferrets have occasionally been recorded in the wild in Western Australia and there are unconfirmed reports they are present on King Island in Bass Strait. In Tasmania some survey work has been carried out at South Arm (coastal, outer suburban Hobart). This is because authorities have received many reports of ferrets at large in that area, as well as from the south-east of the state generally. However, there are currently no confirmed, successfully established ferret populations in the wild in Australia.
Risk management
It is illegal to keep or import ferrets into the Northern Territory and Queensland, and a permit is required to keep ferrets in Victoria and the Australian Capital Territory. Ferrets are permitted in the other states, although in Tasmania and Western Australia it is an offence to release ferrets into the wild.
To help prevent ferrets from establishing in the wild and becoming pests in Australia, it is essential that captive animals are maintained in secure enclosures. Unwanted ferrets should be surrendered to a responsible organisation, not released. Any ferrets seen in the wild should be reported to the nearest relevant government department or wildlife authority so that appropriate action can be undertaken.
Declared pest category
The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Use the links on this page to reach ferrets in WAOL.