The Red fox is the most widespread of all wild canids and has the largest natural distribution of any non-human land mammal. The distribution of the fox covers an estimated 70 million sq-km (~27 million sq-mi) and includes a diverse array of habitats from deserts to Arctic tundra. The distribution of the Red fox can be summarised as being Holarctic, Oriental, Australasian, Northern Neotropical and African. In other words, these foxes are found throughout the UK and Europe east through Russia, Kazakstan, Iraq, Iran, Pakistan into northern India, China and Thailand to Japan. To the west, Red foxes are found in the northern and eastern USA, north through Canada and Alaska to Baffin Island; they're conspicuously absent from many of the Arctic islands including Greenland and Iceland.
Within Eurasia, it appears that the severity of the winter (i.e. the lowest temperature) limits the northern range of the Red fox. This species doesn't appear to have spread far into the African continent, although it is found on the northern fringes (north Morocco, Algeria and Tunisia) and down through eastern Libya, western Egypt into northern and central Sudan, roughly following the course of the River Nile. They are also absent from much of the southern and western USA, Mexico and most of the Southern Hemisphere. Where Red foxes are absent they are typically replaced by other fox species, including the Fennec (Vulpes zerda) and Cape fox (Vulpes chama) in Africa, the Gray fox (Urocyon cinereoargenteus) in most of southern North America and six species of 'Zorro' foxes (Lycalopex spp.) in South America.
At the far north of their range Red foxes are replaced by the Arctic fox (Vulpes lagopus) and, where the two species meet, it appears that Red foxes are dominant and displace the smaller Arctic species. Indeed, in his 1987 book Running with the Fox, David Macdonald noted that the northern range of the Red fox is set by food availability, while the southern range of the Arctic fox is set by the northern range of the Red. Red foxes are generally absent from Arctic tundra because their metabolisms are higher than that of the Arctic fox; they thus require more food than the high Arctic winter can provide.
Recent genetic data published in the journal BMC Genomics suggests that Red foxes are also more heterozygous than Arctic foxes. In other words, the global Red fox genetic code has more variation in it than that of the Arctic fox; this matters because with high genetic diversity comes a greater chance that some of those genes will be able to help you survive in different or changing habitats. Thus, this increased heterozygosity may help explain why Red foxes are able to adapt to many more environments than Artic foxes can. Indeed, as well as surviving in the Arctic, Red foxes also penetrate into the Middle Eastern deserts, although these animals are considerably smaller (averaging 3kg / 6.6 lbs.) than those in Europe.
Red foxes were introduced extensively to North America by early European settlers and Brian Vezey-Fitzgerald, in his 1960 book Town Fox, Country Fox quoted General Roger Williams (the Master of the Iroquois Hunt in Kentucky) who, writing in 1904, said:
“The red fox was unknown in America previous to 1760, at which time a number of them were imported from England and liberated on Long Island in New York.”
Some authors suggest the release was made by one of the first English governors of Long Island, although several early writers (during the early 1600s) mention black foxes—even buying these animals from the native people—but say nothing of red animals. In his 1980 book Red Fox, Huw Lloyd notes that subsequent introductions were made in Maryland, New Jersey, Virginia and several other eastern states - circumstantial evidence suggests this was in response to an absence of foxes in the area. We also know that foxes were introduced to New England from the UK between 1650 and 1750 and, between 1964 and 1967, to six small islands off Massachusetts in a bid to control the population of herring gulls that had been causing problems for local airports; in the latter case the foxes appear to have been highly successful and the population crashed (sometimes the gulls abandoned the island altogether), but left without gulls as food many foxes appear to have starved to death.
Whenever and wherever they were first released, these foreign imports spread rapidly westwards across most of lowland northern North America, as forests were cleared, seemingly to the detriment of the native stock, which now only survive in isolated pockets, primarily at high altitudes (see QA). In his 2003 monograph on the introduced mammals of the world, John Long recounts at least 46 translocations in the Aleutian Islands, mostly in the 1900s, and to the Canadian islands of Baffin, Cornwallis and Ellesmere at some point around 1918. Long also notes that foxes reportedly escaped from fur farms on Vancouver Island (British Columbia, Canada), some becoming established in the Sayward forest north of the Campbell River during the mid-1940s, and that foxes from Canada were introduced to Anticosti and Sable islands in Nova Scotia.
Australia & New Zealand
Australia has also seen its share of Red fox introductions, with animals released to provide sport (rather than rabbit control) by home-sick expatriates who formed the Acclimatisation Society of Victoria; they have arguably caused more serious ecological problems here than anywhere else. In his 1987 book, Macdonald notes that the first confirmed importation of foxes to Australia was the English animals released by T.H. Pike (variously spelt as Pyke by some subsequent authors) onto his property near Keilor in Melbourne, Victoria (on the south-eastern tip of the island) during 1845. Interestingly, in his Introduced Mammals of the World, John Long mentions that it is unknown whether Mr Pike/Pyke's foxes were actually released, although he notes that the Melbourne Hunt Club set an unspecified number of foxes free in the same year. According to Macdonald, two males were subsequently released near Sydney in 1855 and, in 1864, a male and two females arrived on a ship from Suffolk and were released by the Melbourne Hunt Club.
It appears that most of these initial releases failed to 'take' and it wasn't until almost a decade later that introductions began seeing success. It is now widely considered that the present Australian fox population was founded by two shipments liberated in Victoria: one consisted of two foxes released by Dr King near Ballarat in 1871; the second was about five animals released on Point Cook, in the Werribee-Geelong district of southern Victoria, by Mr T. Chirnside in the early 1870s. By 1880 the species was widespread in Victoria (especially between Geelong and Melbourne), but hadn't moved far outside the region; it was at this point that the colonization gained momentum.
In a paper to the journal Mammal Review during 2010, Glen Saunders—at the New South Wales Department of Industry's Vertebrate Pest and Weed Unit—and two colleagues told the story of how the Red fox spread across Australia. The species crossed the south Australian border in 1888, reached New South Wales (NSW) in 1893, and Queensland and Western Australia early in the twentieth century. The rate of movement was particularly rapid (up to 160km/108mi per year) in the inland saltbush and mallee country, and there is some evidence that the spread was actively assisted by humans.
Foxes now occupy all of continental Australia except for the northern arid and tropical regions; they occur across the southern two-thirds of the continent, at least 18 offshore islands, and even penetrate into the hot deserts of the interior when seasonal conditions permit. A single fox escaped from a ship that sailed from Victoria to Hobart Harbour in Tasmania, but an extensive search found and killed it. Foxes were subsequently illegally released on to Tasmania during the late 1990s, although the population didn't become established until 11 animals were deliberately released in three areas of the island in late 1999; carcasses have been found here since 2001.
Recently, foxes have been spotted on Fraser Island and South Stradbroke Island, both off the southeast coast of Queensland in Australia. In a paper to Austral Ecology in 2017, Ben Allen and colleagues report on camera trap images and DNA analysis of droppings that suggest small populations of the red fox now exist on both islands. Foxes started appearing on camera traps on Fraser Island in July 2012, while fox paw prints and a dropping was found on Stradbroke in June 2013 during the regular weed control activities; the faeces tested positive for fox DNA. Both islands are internationally significant wetland sites, home to a variety of endangered species.
Despite reports of a pair of foxes being taken to Christchurch in 1964, there is currently no evidence of foxes in New Zealand and it has been illegal to import them there since 1867.
Britain & Ireland
At the pinnacle of the last ice age, global sea levels dropped by about 120m (almost 400 ft.) and this exposed a 'land bridge' that enabled animals to move freely between Britain and the European continent until it was flooded about 6,500 years ago as the ice began to melt. Fox numbers no doubt waxed and waned in post-glacial Britain, initially with forest cover and subsequently with human influence. Indeed, there are various records in the classical hunting literature of foxes having been introduced from the European continent during the 19th century as numbers ran low for hunting. These introductions appear to have been largely to lowland regions of England and consisted predominantly of foxes from France, Spain, Holland and Scandinavia, although detailed records are patchy, and this seems to have had an influence on the genetic composition of our fox population, especially in the south. The foxes of the Scottish Highlands were historically sufficiently close in morphology to Scandinavian animals as to be indistinguishable and probably represented some of the ancestral post-glacial stock. In the 1964 edition of his The Handbook of British Mammals, Henry Southern comments that the Scandinavian influence among Scottish foxes is the result of imports, but I know of no data to support foxes having been introduced to the Scotland and most translocations within Britain appear to have been out of Scotland into lowland areas of England.
Early hunting literature suggests that foxes became more numerous and widely distributed between about 1750 and 1850, with a further population and range expansion between 1950 and 1965. Indeed, it was during the 1950s that the Red fox expanded its range in Scotland and it has been suggested that the abundance of rabbits dying from myxomatosis permitted this colonization, although some have argued that initial establishment occurred before the first myxomatosis outbreaks and was linked with the planting of conifer forests. Regardless, in 1973, Hugh Kolb and Raymond Hewson suggested that, as rabbits disappeared from much of the countryside, foxes were forced to disperse looking for food (aiding further colonization) and, as vole numbers began increasing in the absence of rabbit grazing, fox populations stabilised.
Red foxes are now common throughout mainland Britain, where they're generally considered native and have been introduced to several islands. This species is absent from all of the Scottish islands except Skye, where they were illegally introduced, and from the Channel Islands and the Isles of Scilly. In their contribution to the 2008 Mammals of the British Isles: Handbook 4th Edition, the Bristol University biologists note that foxes are also present on the Isle of Harris, having been illegally introduced. Scottish Natural Heritage, however, tell me that despite occasional reports of foxes from the island, none have ever been confirmed and no signs have been found by the army of mink trappers that operate on Harris.
Foxes have experienced a tumultuous history on Anglesey; they were relatively abundant until some point during the mid-1800s when they appear to have died out and the island remained devoid of foxes until three animals were released near Holyhead during August 1960. Anglesey's foxes kept a low profile until the late 1960s, when complaints of poultry losses caused them to be hunted; despite intensive fox control throughout the 1970s, the population remained stable. Around 1960 three foxes were released on Holy Island off the Northumberland coast where the population appeared to flourish; 340 adults were killed there in 1974.
Along the south coast of England, foxes are absent from Brownsea Island despite the strong population at nearby Sandbanks; the National Trust rangers there have never had a confirmed case of a fox from the island, although there are occasional reports of brief sightings, the most recent being about ten years ago. Foxes of unknown European origin were introduced to the Isle of Wight in 1845 to provide sport (the Isle of Wight foxhounds were also established in this year) and the establishment of the population was in no small part the work of huntsmen Ben Cotton and Henry Nunn; foxes are now widespread and common on the island.
On some of Britain's islands, the status of the fox is less clear-cut and the situation on the Isle of Man is a good example. There is no archaeological evidence that the fox is native to Man, although there is some evidence that they were present in small numbers during the mid-19th Century, with the first report being an animal killed at Lezayre in the north of the island during November 1861. The foxes of Man kept a low profile until 1986, when four adults were apparently released into the Santon Valley, in the south-east of the island, and then again in 1990, when biologists David Macdonald and Elizabeth Halliwell found a litter of cubs in the same region.
In a 1994 paper to the journal Global Ecology and Biogeography Letters, Macdonald and Halliwell used various factors (e.g. landscape maps, prey densities and distributions, and faecal counts) to estimate that there were between 120 and 300 animals on the island in 1990. It soon became clear that this was probably a considerable over-estimate and, in a 2003 paper to Mammal Review, Game Conservancy Trust biologists Jonathan Reynolds and Mike Short reassessed the situation, concluding that there were likely to be no more than 15 animals across the entire island. Indeed, the researchers noted that foxes may be entirely absent from the island, although there are occasional (unconfirmed) reports from residents.
Most records are held by the Man's Museum of Natural History, but record coordinator Kate Hawkins told me that reports are rare and there have been very few submitted to them since 2002 - the most recent credible report made to her was of droppings discovered in a suburban park in the south of the Isle of Man during November 2009. The Senior Biodiversity Officer on the island, Richard Selman, told me he receives about one fox report per year, of variable credibility—the most recent reliable report being from Ballure, on the edge of Ramsey, in December 2009 that came from a fellow biologist—but is of the opinion that there are, at best, only a handful of foxes on the island. Richard received five unconfirmed sightings in the first half of 2016 - one was followed up, there having been two sightings from the same area, but a trailcam produced nothing other than videos of a large ginger cat.
The situation on the Orkney Isles, off the coast of Caithness, northern Scotland is similarly unclear. In 1936 a pair of foxes were released in the Ysenaby area of Sandwick, West Mainland (Ornkey), but were found dead a few months later. Since then, there have been several reports of foxes 'at large', but none have ever been confirmed. On 12th December 2007, however, a seven-month old male fox was found dead on the roadside at Holm straights between Fea and Cannigal (Orkney) by a gentleman on his way to work (photo, right). Post-mortem analysis revealed that the animal died from blunt-force trauma to the head (having probably been hit by a car) but was in otherwise excellent condition, with pristine teeth and claws. Naturalists Chris Booth and Richard Matson summarized the status of the Red fox on Orkney in a short paper to the Orkney Field Club Bulletin during 2008, concluding that the animal had escaped (or been released) from a private collection and had spent no more than a couple of days in the wild.
The Orkney Isles are currently considered fox-free. At the time, there were rumours that the fox was deliberately planted as a hoax, rather than an escaped pet accidentally run-over. There is, as far as I know, no proof that it was a hoax, but such activities aren't unknown - a fox believed to have been caught in a snare elsewhere was dumped on a road in the south of the Isle of Man during 1990, and the carcass of a fox found on Shetland in 1996 is also believed to have been a hoax.
The picture in Ireland is less clear. We know from fossil evidence that foxes were present in Britain about 35,000 years ago and that there was a substantial land bridge connecting Ireland to the British mainland until sea levels rose at the end of the last Ice Age (the 'bridge disappearing at some point between about 15,000 and 9,500 years ago). There is no logical reason to argue that foxes wouldn't have crossed into Ireland and colonised the country and hence many naturalists consider the species native there today. There is, nonetheless, no fossil evidence to support such an assumption, with the oldest fox remains dating to about 3,800 years ago, during the Neolithic and well after Ireland had been isolated from mainland Britain. Genetic data published by Trinity College geneticist Ceiridwen Edwards and her colleagues in 2012 suggested that British and Irish foxes cluster together (along with foxes from Holland), but we're unable to tell which population was established first or from the other.
There seem to be very few records of recent historical imports of foxes to Ireland. John Long, in Introduced Mammals of the World, notes that 12 foxes were released on Great Saltee Island in Wexford (he doesn't say when), but all of them apparently died. Similarly, in the second edition of his An Irish Beast Book, James Fairley talks about there being a plethora of references for foxes in Ireland from the early 1700s, but that numbers appear to have dwindled significantly at some point in the nineteenth century (a result, it is speculated, of overzealous gamekeepers and shepherds). Fairley notes how, based on letters to journals such as the Irish Naturalist, foxes began being seen again from the early 1920s and by the 1930s were again regarded as a significant pest. In 1943 an official bounty scheme was introduced in Northern Ireland, but reports of dead foxes being imported across from the Republic of Ireland in order to obtain bounties makes it difficult to know whether bounty records paint a representative picture of fox abundance in Northern Ireland.
Elsewhere, Long notes that Alaskan silver foxes (a black colour morph of the Red fox) were introduced to Finland in 1938 with the aim of producing a cross fox hybrid - reports during the 1950s/1960s suggest that interbreeding did occur and had improved the fox fur industry there. Similarly, 251 Canadian silver foxes were released into 61 areas of Russia between 1929 and 1934, again with the aim of improving the fur of the local fox stocks, but it remains unknown whether this had any noticeable effect.