California Department of Fish and Wildlife

Ferrets - World Distribution

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Feral Ferrets in New Zealand

New Zealand Index

New Zealand has the largest population of feral ferrets of any country. Ferrets, the largest of the three mustelid species introduced there (New Zealand Department of Conservation), have had a severe impact on New Zealand's endemic wildlife.

Search the New Zealand Department of Conservationweb pages and recent press releases for information about ferrets (Keywords: ferret, ferrets)

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The Introduction of Domestic Ferrets into New Zealand

Farmers demanded that ferrets be introduced into New Zealand to control the introduced rabbit, a serious agricultural pest. The first introduction included five ferrets released in 1879.- Lavers and Clapperton, pp. 320-330 in King (1990)

"Ferrets arrived in 1882 and the Department of Agriculture bred up large numbers for release. The Department also advertised widely in the British press for live stoats and weasels. Between 1884 and 1886, 4000 ferrets, 3099 weasels and 137 stoats were liberated. Runholders joined in the breeding frenzy." - Rabbit Biocontrol Advisory Group, 1996

"Weasels never became abundant, but stoats and ferrets prospered. As feared by some, the stoats went into the bush and killed many birds - as well as some rabbits. Ferrets were still being bred for rabbit control in the 1920s." - Rabbit Biocontrol Advisory Group, 1996

"Early conservationists could only watch helplessly as more pests, including stoats and ferrets, were introduced to control other introduced pests such as rabbits." - New Zealand Department of Conservation, 1996

"From an ecological and crop damage perspective, a number of the introductions were clearly major disasters. The rabbit was certainly one of these! Attempts to remedy the first mistake led to additional introductions, as early efforts at biological control, e.g. ferrets, stoats, weasels for rabbit control. These early mistakes, both in terms of the introduction of species such as the rabbit and possum, and subsequent introductions in attempts to control them, tend to colour our thinking about the potential value of biological controls." -  Rabbit Biocontrol Advisory Group, 1996

"There is no question that the introduction of rabbit predators (which, in the case of ferrets, have ultimately been very important limiters of rabbit populations) have also had disastrous impacts on many of our native birds. These predators, combined with unwanted introductions such as the three rat species, all helped to create concern regarding introductions." - Rabbit Biocontrol Advisory Group, 1996

Other references on the history of the introduction of domestic ferrets into New Zealand:

Are New Zealand's feral ferrets really ferrets?
Many of the organizations promoting ferret pet-keeping in the U.S. have claimed that the ferrets have been domesticated so long that they are incapable of surviving long in the wild, and that the ferrets in the wild in New Zealand are not true domestic ferrets:

What some New Zealanders have said about the original stock of ferrets of New Zealand:

  • "There are three major color variations to be had in New Zealand ferrets. The darker ferret with its white to yellow underfur and black guard hair is called the standard. This is the animal erroneously called the polecat." - Jeffares (1986)
  • "The average New Zealander who encounters the ferret in its feral state quite wrongly terms the darker ferret with its racoon-like mask to be a polecat. Polecats were not liberated in New Zealand, or at least no record exists of their liberation.Jeffares (1986)
  • "The earliest releases included many individuals with unnatural coat colours bred up by artificial selection during domestication, but most of these have reverted to the wild-type coloration similar to the polecat." - Lavers and Clapperton, pp. 320-330 in King (1990)
  • "It is possible that the original introductions included genuine wild polecats (M. p. putorius) as well as ferrets. There is much variation in coat colour, which Wodzicki (1950) took to mean that there were 'at least two wild animals to which the term "ferret" is frequently applied'; but these variations may be found within one litter (B.K. Clapperton, unpubl.). Most New Zealand ferrets are still docile when trapped, even after generations in the wild, which implies that there is little wild polecat in their ancestry (B.M. Fitzgerald, unpubl.)."- Lavers and Clapperton, pp. 320-330 in King (1990)

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Ferret Biology in New Zealand

Range and habitat

"In New Zealand, ferrets traditionally have been limited to pastoral habitats, rough grassland, riverbeds, scrub-land and the fringes of nearby forests. Disturbing information has been revealed which shows that ferrets are penetrating deep into the forests in Northland." - New Zealand Department of Conservation

"Ferret ranges are over 31 ha for males and 12 ha for females." (from Moors, P.J., and Lavers, R.B. 1981. Movements and home range of ferrets at Pukepuke lagoon, New Zealand. New Zealand J. of Zool. 8: 413-423).

Ferrets are highly mobile. "Male ferrets have been tracked over 1.8 km." (from Moors and Lavers, 1981).

"Movement studies indicate that ferrets may expand their home range from 85 ha to 230 ha, or disperse up to 4.3 km from the center of their range when 99% of rabbits are removed from an area (Norbury et al.1998)." - Moore, T.G., and D.A. Whisson 1998

"Home range and spatial organisation of stoats (Mustela erminea), ferrets (Mustela furo) and feral house cats (Felis catus) on coastal grasslands, Otago Peninsula, New Zealand: implications for yellow-eyed penguin (Megadyptes antipodes) conservation ."- Moller, H., and N. Alterio. (1999). New Zealand J. Zoology (Abstr.), Vol. 26(3)

Dietary studies

"Although ferrets prey largely on lagomorphs, diet analysis indicates that ferrets are "opportunistic generalist predators " (Smith et al. 1995)" -

Ferret diet in pastoral habitats: The diet of the ferret was studied from prey remains in the digestive tracts of 277 live-trapped animals from Otago and Southland. Lagomorphs constituted 77% of the diet by weight and were identified in 65% of the ferrets sampled. Other important items were hedgehogs (Erinaceus europeus), possums (Trichosurus vulpecula), and birds. - Smith, et al., New Zealand Journal of Zoology, 1995, Vol. 22: 363-369.

"In a grassland surrounding a yellow-eyed penguin colony along the southeastern coast of the South Island of New Zealand, birds were identified in 50% of ferret guts and lagomorphs were found 42% of the time (AIterio and Moller 1997). The primary bird species eaten were sooty shearwaters (Puffinus griseus) and little blue penguins (Eudyptula minor)." - Moore, T.G., and D.A. Whisson 1998

"The number of ferrets known to be alive on the control site naturally cycled with peaks in summer/autumn (due to recruitment of young ferrets and to an increase in trappability), and lows in winter/spring (due to high post-recruitment mortality and to a decline in trappability). Based on survival of radio collared ferrets, about 60% of the ferret population naturally dies off every year, so high ferret mortality is a natural feature of ferret dynamics in semi-arid New Zealand." - Predator-Prey Interactions and Impacts of Rabbits, Dr G Norbury, Landcare Research

In New Zealand, "Night surveillance using night vision time-lapse videos was also used to study the scavenging behaviour of ferrets, clearly showing ferrets eating a variety of carrion including dead ferrets." - Ag Research Invermay.  The scavenging behavior of ferrets is a factor in the spread of bovine tuberculosis, (described below).

For other information on diet of ferrets in New Zealand, see:

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Fur Market in New Zealand

"Specially-bred ferrets, called fitches, have been farmed in New Zealand for their fur."  - New Zealand Ministry of Agriculture and Forestry

Royal Forest and Bird Society conservation officer Basil Graeme said, "Ferrets have been in New Zealand for many years but were spread to many new areas of the country in the late 1980s when short-lived ferret farming ventures collapsed and the ferrets were released. ." - Royal Society of New Zealand, 1996

"In the 1980s, ferret farms were established throughout New Zealand with a view to the export fur trade. When the fur market became unprofitable, most of these farms closed down. Ferrets escaped or were set free, allowing the invasion of ferrets into some of New Zealand’s remaining prime kiwi habitat." - New Zealand Department of Conservation

The use of New Zealand's feral ferrets for the fitch fur market was evaluated by Jeffares, R. 1986.

Control of Ferrets

Ferrets are trapped to protect vulnerable species, such as penguins and kiwis, although they are difficult to control. "They are tenacious and wary creatures, which makes controlling ferrets a difficult proposition requiring considerable resources."

In the mid 1990s, research on predator control program strategies was undertaken to protect a brown kiwi population from ferrets and other predators in Urewera National Park - The Royal Forest & Bird Protection Society, 1997

Ferrets and other predators had to be removed from the Karori Wildlife Sanctuary to create a "land island" fenced sanctuary for threatened wildlife on New Zealand's mainland.

A landowners agreement containing "cat, dog, stoat and ferret-free conditions" was made to protect kiwi and other native wildlife at Kerikeri Inlet, New Zealand, from threats of domestic pets in a new housing development. - The Royal Forest & Bird Protection Society, 1997

Vertebrate pests: impacts and future management - Phil Cowan, Landcare Research

New Controls on Ferrets?  Public Discussion Document

Public Discussion Document
September 1999
(PDF, 446K)

"The Department of Conservation is reviewing the regulations which control the farming, breeding and sale of ferrets and which allow ferrets to be kept as pets. This review has been instigated because of concerns that controls on pet ferrets are too loose and that existing controls on breeding and sale of ferrets are being ignored."

May 2000
(PDF, 264K)

Canterbury Regional Council's submission to the Department of Conservation on the review, Feb. 2000

"Ferrets may look like furry friends, but they are kiwi killers. If we are to save our natural icon and other important native species, we need to get serious about proper controls on ferret ownership."- New Zealand Conservation Minister Nick Smith, Media Release, 30 September 1999

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Threat to New Zealand's Wildlife

"The introduction of mustelids was first proposed in 1881 to control the rabbit scourge. Concerns were expressed at the time that mustelids may seriously endanger our native fauna. Although they reduced rabbit populations, mustelids were major players in the decline and loss of some of our native fauna. Ferrets are mostly ground dwelling and eat small mammals, birds, lizards and frogs." - Wellington Regional Council

There have been concerns that current attempts in New Zealand to rid areas of European rabbits could lead to increased damage to native wildlife, because rabbit predators, such as the ferret, might shift their feeding habitats and feed more heavily on native animals (see "Prey Shifting").

What some New Zealanders have said about the impacts of introduced ferrets in New Zealand:

King (1984) wrote, "So, surprising as it may seem, mustelids cannot be proved to be directly responsible for any of the shockingly long list of island populations of birds that we know to have become extinct since the human colonization of New Zealand, and they can be suspected of finishing off only a handful of South Island species and perhaps, the huia.  By contrast, the record of cats is very black, and of man and rats worse still."  Dr. King went on to explain, "This is not to say that the mustelids were not capable of inflicting as much damage, or more: it is simply that they did not have the opportunity. The worst damage is always done by the first predators to arrive, which were usually men in boats (canoes or sailing ships) and the animals that they carried with them."

"Rabbits were introduced last century, for hunting. But by the 1870s farmers had already decided they were a pest, and so introduced mustelids - stoats, weasels and ferrets - to kill the rabbits. Ferrets were later farmed in Northland for their fur. These mustelids have decimated ground nesting birds. In May stoats were declared "public enemy number one" for New Zealand birds." - New Zealand Department of Conservation (1999)

"By 1900, ferrets were well established in the wild and definitely played a role in the decline of native birds like the kiwi, weka and blue duck, and the extinction of kakapo on the mainland." - New Zealand Department of Conservation (1999)

"Ground-nesting birds like the rare New Zealand dotterel and extremely rare black stilt, flightless birds like the kiwi, rare lizards and insects are eaten by ferrets. Even the yellow-eyed penguin, blue penguin and royal albatross are not safe from ferrets. Ferrets love eggs and attack and kill chicks and adult birds - even adult kiwi. Threatened giant weta make a tasty snack and geckos and skinks are not immune from the dangers ferrets pose." - New Zealand Department of Conservation (1999)

"The extinction of the kakapo from the Mainland and the probable extinction of the South Island kokako is attributed to stoats. Every year they kill 60 per cent of the 15,000 North Island brown kiwi chicks born, with another 35 per cent falling prey to other predators like ferrets. Stoats and ferrets are endangering the future survival of our national icon." - New Zealand Department of Conservation (1999)

Introduced species like possums, rabbits, stoats and ferrets have proved to be an environmental disaster." - New Zealand Conservation Minister Nick Smith, Media Release, 15 July 1999

"Ferrets are an introduced animal which have a severe impact on New Zealand endemic and often endangered wildlife." New Zealand Conservation Authority, December 15, 1999

...and what some pet ferret organizations have said about the impacts of domestic ferrets in New Zealand:

"...naturalists have concluded on the basis of decades of field studies that the ferrets living in that unique Southern Hemisphere country have not had a demonstrably destructive impact on the ecology." - H. Davis, The INDEPENDENT VOICE, ACME Ferret Company, 1996

"The only places where ferrets have managed to survive in the wild, and they didn’t ”wreak havoc” there either, was where we intended them to: New Zealand...The ferret managed to survive in the predatorless environment of New Zealand for one reason: it was predatorless." - Californians for Ferret Legalization, 1997

Examples of Impacted Species

Weka, Gallirallus australis, or New Zealand Woodhen, a flightless rail.

Atlas of bird species maps (JavaScript) (select: Rails, Gallinules & Coots: Rallidae: Weka)

"By 1900, ferrets were well established in the wild and definitely played a role in the decline of native birds like the kiwi, weka and blue duck, and the extinction of kakapo on the mainland." - New Zealand Department of Conservation (1999)

"Ferrets endangering native birds: Society conservation officer Basil Graeme said that ferrets had recently wiped out a small population of North Island weka liberated by the society in the Karangahake Gorge, Waihi, near Thames. Mr Graeme said ferrets were a serious predator of ground-dwelling native birds, including penguins and kiwi. [ ... ] Mr Graeme said hopes had been high for the small weka population established in the Karangahake gorge when seven wild chicks were seen in the spring. However, local managers Elaine and Gary Staples became worried when the weka stopped calling and sightings dropped off in December. Their worst fears were realised just before Christmas when they found mauled weka bodies, and Mr Staples trapped a pregnant female ferret." - Royal Society of New Zealand, 1996

The Royal Forest and Bird Protection Society (press release of Dec. 17, 1998) stated that "there was a substantial body of scientific evidence on the impacts of ferrets. Forest and Bird also has first hand experience as ferrets were responsible for wiping out a small population of weka Society members had reared and released into the wild near Waihi."

Yellow-eyed penguin (Megadyptes antipodes)

Atlas of bird species maps (JavaScript) (select: Penguins: Spheniscidae: Yellow-eyed penguin)

"Predation by introduced stoats (Mustela erminea) and ferrets (M. furo) may be contributing to the decline of yellow-eyed penguins (Megadyptes antipodes) on the South Island of New Zealand." -  H. Ratz. New Zealand J. Zool., 27(1) Mar. 2000

"The yellow-eyed penguin is confined to the New Zealand region and is one of the rarest of our penguins." ". . . the biggest threat to the survival of the species is introduced mammalian predators. Wild cats, ferrets and stoats often kill chicks and take eggs."  - New Zealand Penguins

"Ferrets, stoats and cats, all introduced, prey on the penguin chicks to a disastrous degree." - The Yellow-eyed Penguin Trust

"The trapping of predators occurs in many mainland yellow-eyed penguin colonies to ensure the survival of chicks." - New Zealand Penguins

Blue penguin, Eudyptula minois

Atlas of bird species maps (JavaScript) (select: Penguins: Spheniscidae : Blue penguin)

The Blue penguin, the world's smallest penguin, is found around New Zealand and Southern Australia.

"Blue penguins are particularly vulnerable to the mustelids, and a single ferret may kill a dozen birds in one night." - New Zealand Penguins

"Predation by ferrets, stoats, cats and dogs has decimated many colonies."- New Zealand Penguins

Link to Penguin conservation in New Zealand

Brown kiwi, Apteryx australis, and Little spotted kiwi, Apteryx owenii

"Two hundred years ago there were millions of kiwi living in New Zealand. Today the population is about 75,000 and this is halving every decade. Introduced predators, like possums, stoats, ferrets, cats and dogs are the main threat. The kiwi has also suffered from a huge loss of its natural habitat and is in real danger of disappearing from mainland New Zealand. One species, the Okarito brown kiwi is down to just 152 birds."  - Dr. N. Smith, New Zealand's Minister of Conservation, April 1998.

Atlas of bird species maps (JavaScript) (select: Kiwi: Apterygidae: Brown kiwi)

Description and photos of New Zealand's kiwis

KEEP UP ON THE LATEST NEWS about the threats ferrets pose to New Zealand's national bird.  Use the search page for the Kiwi Recovery Programme (Keywords: ferret, ferrets)

Ferrets eat kiwi eggs and kill adults. - Kiwi Recovery Programme

"A common theme runs throughout all reports about the kiwi. Numbers and distribution are in rapid decline on the two main islands. All reports identify stoats, ferrets, dogs, cats and possums as the major threats." - Royal Forest and Bird Protection Society of New Zealand

"The first Operation Nest Egg-raised kiwi to be sitting on an egg has been killed by a ferret..." - New Zealand Department of Conservation Press Release, 8 December 1999.

"Threats to Kiwi - Dogs, ferrets, possum traps and cyanide poison, vehicles and perhaps pigs, are the major threats to adult kiwi; and possums, stoats and microbes are major threats to kiwi eggs. As has already been noted, 95% of kiwi chicks do not survive the first six months, mainly due to predation by stoats and cats."  - Kiwi Recovery Programme

The mainland island habitat of Trounson Kauri Forest supports "the highest-density of North Island brown kiwi populations in Northland, under threat from a northward-advancing ferret population." - New Zealand Department of Conservation

"The ferret, also known as fitch or polecate (sic), is the largest of the mustelids and is not only capable of eating kiwi eggs and killing chicks, but can kill adult kiwi too. In one bush patch in Northland a single male ferret killed three of ten breading (sic) males and destroyed two other nests within a three month period before he was trapped." - Kiwi Recovery Programme

"A comparison of their surveys with those from 1970, shows kiwi noticeably dwindling in Northland, Hawke's Bay, Bay of Plenty and the West Coast. The decline in Northland coincided with the movement of possums and ferrets into southern Northland, the former inexorably spreading to the farthest corners of the country, and the latter roaming free after being released by disgruntled farmers following the collapse of the fitch fur industry in 1987." - The Royal Forest & Bird Protection Society, Forest and Bird, Nov. 1995

"For adult kiwi, the greatest risks are dogs, ferrets, possum traps, cyanide poison, cars, pigs, and rarely, possums; chicks are vulnerable to stoats, cats, harriers, ferrets, and possibly weasels; eggs are predated by possums, stoats, pigs and sometimes weka." - The Royal Forest & Bird Protection Society, Forest and Bird, Nov. 1995  

"Little Spotted Kiwi were wiped off the mainland at the turn of the century, their small size making it impossible for them to fend off predators like stoats, ferrets and dogs." - Northland Kiwi News, June 1997.

Ferrets are a serious threat to the large kiwi population in Taranaki forests of North Island. "Stoats, ferrets, and cats are eating kiwi chicks in such great numbers, that it's extremely unlikely the kiwi population will recover without help."- Kiwi News, March 30, 1998.

"In 1998-99 kiwi breeding season, a male ferret killed at least five kiwi over a few months before it was trapped and killed".- New Zealand Department of Conservation.

"Stoats and ferrets are endangering the future survival of our national icon." - New Zealand Department of Conservation

Black Stilt - Himantopus novazealandiae

Atlas of bird species maps (JavaScript) (select: Stilts & Avocets: Recurvirostridae:  Black stilt)  [photo]

" REASONS FOR DECLINE Nesting areas have been destroyed by drainage hydroelectric development, (and by weed growth, tree planting and flood control programmes). Suffers from heavy predation, which is sharply increased by its nesting preference for dry banks, the favoured hunting habitat of introduced cats and ferrets. The species prefers habitat little frequented by stock." - UNEP World Conservation Monitoring Centre

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Ferrets as a Factor in Bovine Tuberculosis in New Zealand

"While predators, particularly ferrets, are an important means of rabbit control, they are also known to be infected with Tb (one of the country's greatest agricultural threats) in many areas. If it proves necessary to control ferrets to help reduce Tb in livestock, a significant increase in rabbit control will be required. The maintenance of ferret populations by rabbits also affects the conservation of native species, particularly ground nesting or burrowing species such as penguins." - Australia and New Zealand Rabbit Calicivirus Disease Program

"Predators, particularly ferrets, are very important rabbit controllers. However, they are now also known to be infected with Tb in many places. They have now been officially declared Tb vectors. This means they can now be controlled under the Agricultural Pest Destruction Act (1967) until the Pest Management Strategy for Tb comes into effect. Control of ferrets will probably result in an increase in rabbits - thus more rabbit control." -  New Zealand Ministry of Agriculture and Forestry, Rabbit Biocontrol Advisory Group, 1996

"Surveys show up to 30% of ferrets are Tb carriers. To remove this potential source of infection to New Zealand’s cattle herds, the feral ferret population now needs to be reduced. This could be done directly by a labour intensive programme of poisoning and trapping, or indirectly, by cutting back its main food source in many areas, the rabbit." - New Zealand Ministry of Agriculture and Forestry, Rabbit Biocontrol Advisory Group, 1996

"Ferrets scavenge extensively, and, although their diet mainly consists of rabbit, dead and possibly also live brushtail possums are also eaten (Roser & Lavers 1976;Smith et al. 1995; Ragg 1998). As ferrets are highly susceptible to M. bovis infection, administered either orally or subcutaneously (Dunkin et al. 1929), their scavenging of tuberculous carcasses is likely to result in infection." - National Science Strategy Committee for Possum and

Bovine Tuberculosis Control, 1999  

Other bovine tuberculosis information sources:

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Prey Switching and Rabbit Control

"Studies of the impact of controlling rabbit populations on the ecology of wild cats and ferrets have indicated that ferrets, and to some extent cats, shift their diet to other fauna following rabbit control. Ferrets ate lizards, insects and hedgehogs and cats ate birds. Ferret and cat numbers declined slowly after rabbit poisoning: the main effect appeared to be on breeding. There was some starvation of ferrets, but not of cats, and little secondary poisoning or dispersal of either animal. It is estimated that about 60% of the ferret population and 30% of cats die anyway each year, of natural causes." - Predator-Prey Interactions and Impacts of Rabbits, Dr. G. Norbury, Landcare Research

"Dr Norbury recently completed a study of how rabbit control with 1080 poison affects the behaviour of predators. At sites where 1080 killed 77% and 99% of rabbits, Dr Norbury found that ferrets ate fewer rabbits and more skinks, geckos and insects. The change in ferrets diet was greatest where rabbit control was most effective. The diet of wild cats in the area did not change significantly." - The Authority (N.Z.), Sep. 1997

New Zealand studies were reviewed and considered at a workshop, and "major habitat types, containing 20 native species that are vulnerable to increased predation when rabbit numbers decline, were identified." - Predator/Prey Interactions in New Zealand, Rabbit Biocontrol Advisory Group

"We need to determine whether predator-prey switching poses a risk for threatened species and whether this threat can be alleviated by predator control." - E. Murphy, New Zealand Department of Conservation, Sep. 1998

"Some rabbit populations are now 1080 and bait-shy, reducing the control effectiveness. In many areas, another important biological control of rabbits, ferrets, have Tb and may have to be controlled to prevent spread to livestock. If so, rabbits are likely to increase again in many areas. Other methods of control are therefore likely to be needed." - Rabbit Biocontrol Advisory Group

[Note: Rabbit Hemorrhagic Disease (RHD) and Rabbit Calicivirus Disease (RCD) refer to the same viral disease.]

Other information on prey shifting by ferrets and other species in New Zealand:

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Feral Ferrets in Australia


"An isolated population of ferrets exists to the south of Launceston in Tasmania.  It is remarkable that the ferret is not more widely distributed in Australia, given it popularity for rabbiting." - Wilson (1967).  However, "it is uncertain if the population persists today (Bomford 1991; Wilson et al. 1992)." - Moore and Whisson 1998


In Queensland, the ferret is prohibited as a pet.

"Camels, horses, donkeys, water buffalo, ferrets, dogs and various rodents are also feral in Australia, although these are not seen as posing a significant threat to native species at this time. Environmentally many have the potential to be destructive and species such as the water buffalo have been subjected to severe control measures to minimise their impact on northern wetlands. To varying degree they all pose some threat due to habitat alteration, competition and/or predation and it is likely that some control measures will be imposed when (if) cost benefit analysis shows action to be either desirable or necessary." - Economically Viable Alternative Green, August 31, 1998.

"Rising [feral] ferret numbers in south-east Queensland have raised fears for wildlife. Department of Natural Resources officer Nigel Gallas said Beaudesert Shire sightings had leapt from none to six in a few weeks and it was "totally illegal" for private people to keep ferrets." - February 20, 1999 - Ferret alert - Courier-Mail Brief

Feral Ferrets in Europe

"Ferrets survive in the presence of other mammalian predators like the red fox in England where escaped ferrets have become well established in the northern portions of the country (Macdonald 1995). Feral ferret populations have become established in the wild on the Scottish islands of Arran and Bute, on the Isle of Man in the Irish Sea, and on the Isle of Anglesey off the Coast of north Wales, as well as in Renfrewshire and parts of Yorkshire (Walton 1977)." - Moore, T.G., and D.A. Whisson 1998

A feral ferret-polecat hybrid population on Shetland Island. - Terrestrial Mammals of Shetland

  • Phylogenetic releationship of the Shetland  Island population - Davidson, A., et al. (1999)

"Established feral populations resulting from escaped domestic ferrets are found in parts of Britain, especially on islands (Anglesey, Man, Lewis, Arran) and also on some Mediterranean islands (Sardinia, Sicily). They are not likely to persist as separate, recognizable forms where wild polecats occur." - Corbett and Ovenden (1980)

In Britain, “Since ferrets are widely kept, escaped animals may be encountered anywhere and make it difficult to detect well established feral populations.” - Corbett and Southern (1977)

In England, "Feral ferrets (domesticated animals that have been released or escaped into the wild) are, unfortunately, all to (sic) common in this country, probably brought about by uncaring owners." - National Ferret Welfare Society

In the British Channel Isles, the island of  "Jersey has Red Squirrels, Stoats, Polecats, naturalised Ferrets, Water and Bank Voles and the Common Shrew, none found in the other islands." - Islander Magazine Issue 4 July 1997.  "Green lizards (Lacerta viridis) and wall lizards (Podarcis muralis) are native to Jersey and are found nowhere else in the British Isles. The latter species hangs onto a precarious existence on a number of man-made sites in the north east of the Island while green lizards are found predominantly in the south and west since the urban development of the south east corner of the Island. Both species are vulnerable to predation by cats and ferrets. " - The Agile Frog Group, 2000

European polecats , which had declined drastically in England, has repopulated many areas in the latter half of this century, but "there is widespread concern for its genetic integrity because of hybridization with domesticated, escaped, and feral ferrets (M. furo)." - Judith M. Rhymer and Daniel Simberloff , Extinction by hybridization and introgression, Annu. Rev. Ecol. Syst. 1996, Vol. 27: 83-109.

"On the island of Mull off the west coast of Scotland, where the polecat has never been indigenous, ferrets and polecats were both kept in domestication in about 1933-4; they soon escaped and interbred freely in the wild, before long becoming pests throughout the island where they preyed on rabbits, ground-nesting wild birds and domestic poultry." (Lever, 1985).  Recently on this island, there were reported ". . . polecats, weasels, stoats, feral ferrets, rabbits, blue and brown hares and rats."  

"Feral ferrets are established in the wild in many places in continental Europe, being especially common, according to Roots (1976), in Sicily and Sardinia." (Lever, 1985).

Ferrets are listed among the carnivores of the island of Malta, in the Mediterranean Sea. Here, the ferret " an introduced form of the European species and has been kept in semi-domestication since ancient times, being used for driving out rats and rabbits from their burrows. Specimens in the wild are usually escapees from domestication."

The ferret (Mustela putorius furo) is listed among the species of mammals recorded on the island of Mallorca in the Balearic Islands and is included in the list of mammals of Spain and Portugal.

Skopelos Island, North Sporades, Greece. "Hedgehogs, hares, ferrets, tortoises, field-mice, bats and snakes belong to the fauna of the island."

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Feral Ferrets in North America

The European ferret is included among the 28 species of exotic mammals of North America listed in the Revised Checklist of North American Mammals North of Mexico, 1997: "Based on information presented by Hoffmeister (1986) and Jones and Schmitt (1997), we have added Mustela putorius, European ferret, to the checklist."

In the 1996-97 nationwide survey, respondents in six states reported being aware of domestic ferrets living more than a few days in the wild or suspected that ferrets had formerly bred in the wild. The following summaries describing free-living ferrets in three of the states is from material provided in conjunction with the recent survey or from prior material available to the Department and affirmed by the survey.


Two healthy, free-living ferrets were caught by fur trappers in December 1985, and another one was caught in December 1986, in southeast Alaska.  Also, a road-killed ferret was found near Ketchican in December 1985. There was no evidence of breeding.  

This October 26, 1987 letter [Page 1 - Page 2] from Alaska Department of Fish and Wildlife summarizes the information collected on these free-living ferrets. The letter was written by that agency in response to a 1987-89 nationwide survey of state agencies by California Domestic Ferret Association regarding the status of ferrets in each state. However, this letter was not included in the collection of state reply letters (mostly wildlife agency responses) in the report entitled, "50 State Survey on the Supposed Existence of Feral Populations of Domestic Ferrets in Each State."  That California Domestic Ferret Association report was part of ferret organizations' presentation packets provided to the California Fish and Game Commission for the August and November 1995 and February and April 2000 hearings on ferret legalization. Instead, the Alaska response letter that was included in the packets was an August 22, 1989 letter [Page Link] from Alaska Division of Agriculture, replying simply that they have not collected data on domestic ferrets in Alaska. This Agriculture agency letter was tallied in that report as being one of the 46 replies from "State Departments of Fish and Game (or equivalent)".

New Mexico  

Feral ferrets were reported in the 1980s in several locations in New Mexico, mainly the result of legal, purposeful releases of ferrets in prairie dog towns as a biological control method. 

The following letters dated October 7, 1987 [Page 1 -  Page 2], October 27, 1987 [Page 1 - Page 2], November 6, 1987 [Page Link], and August 2, 1989 [Page 1 - Page 2], were provided by New Mexico Department of Game and Fish to representatives of two ferret organizations in reply to survey letters requesting or clarifying information on the occurrence of feral ferrets in New Mexico. None of these reply letters was included in the California Domestic Ferret Association report. Instead, a copy of a California Domestic Ferret Association survey letter of August 11, 1989 [Page link] to New Mexico Department of Agriculture, with a reply marked on it, was included as that state's response. As in the Alaska instance, this letter was tallied in that report as being one of the 46 replies from "State Departments of Fish and Game (or equivalent)".


On San Juan Island, Washington, a feral ferret population was discovered accidentally in 1974 (Stevens, 1975Stevens, 1982), when domestic ferrets were unexpectedly caught in rabbit traps during a study of the European rabbit population on the island by the National Park Service. However, no research was conducted on the ferrets, the impact of the ferrets on wildlife was not investigated, and the presumed disappearance of the population sometime in the 1980s was not documented.  Ferrets had been used in the sport of ferreting to capture rabbits on this island (see Ferrets Used in Hunting Game and Rodents).

The European ferret is one of the species listed among animals treated at the wildlife rehabilitation center on San Juan Island since 1983 - Wolf Hollow Wildlife Rehabilitation Center.