The red fox is a member of the family Canidae which includes wolves, jackals and coyotes. Males are slightly larger than females. Both males and females, but particularly females, have seasonal variations in body weight. Geographic and subspecies variations in size also occur. Adults have a head and body length of 570 to 740 mm, a tail length of 360 to 450 mm and weigh between 4.5 to 8.3 kilograms (Coman 1983, in Saunders et al. 1995). In general, throat and abdomen are white, lower legs and ears are black and a bushy tail is tipped in white. Three colour morphs of V. vulpes are recognised: red, silver/black and cross. A pale-yellowish colour morph is common on the Arabian peninsula and within native subspecies in North America.

There is a close relationship between fox and rabbit numbers (Saunders et al. 2007). When rabbit populations crash, due to drought, myxomatosis or Rabbit Calicivirus Disease (RCD), there will be a lag period until fox numbers decline and adjust to the reduced prey population. The likelihood of increased predation pressure on native wildlife over this period needs to be considered. Rabbit numbers may also be affected by foxes. Preliminary studies suggest that foxes and feral cats may slow the recovery of rabbit populations after they crash due to drought or disease. The potential role of foxes in rabbit control and the impact of foxes on native wildlife following crashes in rabbit populations needs to be clarified (Saunders et al. 2007).

Parturition occurs after a gestation of 51 to 53 days. Lactation lasts for approximately five weeks and weaning occurs gradually. Females can breed before one year of age, however, in areas of high density most yearlings do not produce pups. V. vulpes can live up to 9 years in the wild, although few individuals live more than 6 years. In the northern hemisphere, dispersal usually occurs from September to January.

Wild-caught V. vulpes are used in sport hunting. Foxes are also raised in farms, where they generate millions of dollars a year worldwide; for example in the EU from 2001 to 2002 fur farms generated US $4 600 million (International Fur Trade Federation Undated). Most of the world’s farmed fur is produced in Europe, accounting for 63% of fox production (EU = 47%); Finland is the world’s largest producer and exporter of fox skin (International Fur Trade Federation Undated). Russia/the Baltic States and China account respectively for 11% and 27% of fox production (International Fur Trade Federation Undated).

The worldwide distribution of the red fox, ranging from tundra to the desert as well as urban areas, suggests that it can survive in most sorts of environments (Saunders et al. 1995). The fox is probably most abundant in fragmented environments typically found in agricultural landscapes because these offer a wide variety of cover, food and den sites (Saunders et al. 1995). More uniform, open environments are less favoured as are heavily forested or mountainous areas. Foxes do not live entirely within closed canopy forests but can penetrate some distance into them in search of food (Jarman 1986, in Saunders et al. 1995). The red fox appears to be absent from areas with tropical climates, such as Asia, although the reasons for this are unclear. In Australia the fox can survive in habitats ranging from arid through to alpine as well as urban. The only limitations on distribution appear to be the presence of dingoes and the tropical climate of the northern parts of Australia (Saunders et al. 1995).

Females reproduce only once a year. Gestation lasts 51 to 53 days with most cubs born during August and September. In Australia females are reproductively active from July to October with a peak during August in southeastern Australia (McIntosh 1963a, Ryan 1976a, in Saunders et al. 1995). In temperate regions breeding occurs from December to April (later in more northern latitudes). Mean litter size is four up to a maximum of about ten (Saunders et al. 1995). Both sexes become sexually mature from ten months of age (Saunders et al. 1995). Although social groups of one male and several vixens do exist, most foxes are thought to have only one mate; males may also leave their normal territory temporarily in search of other mating opportunities (Saunders et al. 1995).

Foxes prey particularly on small to medium-sized, ground-dwelling and semi-arboreal mammals, ground-nesting birds and chelid tortoises (DEWHA 2008b). Terrestrial mammals in Australia at the greatest risk are those that weigh between 35 g and 5.5 kg (critical weight range species), including ground-nesting birds, many of which are endangered or vulnerable (DEWHA 2008a). Although predominantly carnivorous, the fox is an opportunistic predator and scavenger with no specialised food requirements (Saunders et al. 1995). Foxes are omnivorous, consuming fruit, vegetables, eggs and insects, especially when they are seasonally available. Diet studies conducted in Australia show rabbits, house mice and sheep taken as carrion to be the most common food items (Saunders et al. 1995).

Introduced for sport hunting purposes in Australia and USA

Reduction in native biodiversity: The damage to Australian wildlife since European settlement has been catastrophic (e.g. Salo et al. 2007). At least 20 species of Australian mammals have become extinct (Saunders et al. 1995). This represents about one half of the world’s mammal extinctions in the last 200 years; a further 43 species are judged to be either endangered or vulnerable (Commonwealth Endangered Species Advisory Committee Report 1992, in Saunders et al. 1995). The causes are complex and the impact of foxes on wildlife have probably been exacerbated by habitat modification and fragmentation (Saunders et al. 1995).

In Austrialia the fox has eliminated remnant populations of some native rodent and marsupial species. The best known Australian example of impact on a native species as reported by Saunders and colleagues (1995) is that of the 'Near Threatened (NT)' black-footed rock-wallaby (Petrogale lateralis), living in small, relict colonies in the wheatbelt of Western Australia. Management of local fox populations using poisoned baits resulted in a substantial increase in wallaby numbers. Another threatening process which has recently come to light is the impact of predation by foxes on native marsupials and on the 'Vulnerable (VU)' malleefowl Leipoa ocellata) (Saunders et al. 1995). For more examples of Australian fox removal studies please see Saunders et al. 1995.

In North America, introduced foxes have negative impacts on many ground-nesting birds, such as ducks and grouse. In California, European red foxes have to be controlled on an annual basis to protect the nesting grounds of several endangered species of birds. European red foxes also negatively impact smaller native canids, such as the endangered San Joaquin kit foxes and subspecies of native red foxes.

Competition: The impact of competition by foxes appears to be secondary to that of predation. Morris (1992) suggests foxes may compete with the chuditch or western quoll (Dasyurus geoffroii) for food in jarrah forest in Western Australia. Foxes also prey on young chuditch.

Agricultural: European red foxes are also a threat to livestock as they prey on poultry, lambs and kids.

Disease Transmission: In its introduced range in Australia the fox carries no diseases of serious economic or public health significance, although recently foxes have been found to harbour the hydatid parasite (Saunders et al. 2007). Controversy still surrounds its possible role as a wild reservoir host for the rabies virus (Saunders et al. 2007). In many parts of the northern hemisphere, the fox is the main reservoir of this disease and, given the widespread distribution of foxes in Australia, the possibility of rabies developing as an established disease in fox populations cannot be dismissed (Saunders et al. 2007).

Many other infectious diseases occur in foxes, although little is known of their incidence in Australia, or their impact on population regulation. These include mange, canine distemper, parvovirus, toxoplasmosis, canine hepatitis, tularaemia, leptospirosis, staphylococcal infections and encephalitis (Saunders et al. 1995). Like most carnivores that feed on a wide range of prey, foxes also carry a variety of endoparasites (Saunders et al. 1995). The incidence of helminth parasites, in foxes in particular, has been intensively surveyed in southeastern Australia because of their potential transmission to domestic animals (Saunders et al. 1995).

An analysis by Salo and colleagues (2007) has confirmed that introduced predators generally have detrimental impacts on populations of native species. Impacts on prey are much greater in Australia than in other parts of the world. Since the early days of European settlement in Australia, control of predators has been attempted using a variety of methods, including shooting, trapping, fencing and poisoning (Rolls 1969, in Glen et al. 2007). Control of urban foxes also presents a problem, as conventional lethal techniques (e.g., shooting, poisoning and trapping) cannot be used in built up areas. Efforts are now directed towards mitigating the impact of the fox using baits to deliver vaccines or poisons or to regulate fertility (Armstrong 2004; Marks et al. 1996; Vos 2003). The ongoing costs of fox control are high. To aerially bait approximately 35 000 square kilometers/year costs approximately $1.3 million (Saunders & McLeod 2007, in DEWHA 2008b). Exclusion fencing costs up to $10 000/km (DEWHA 2008b).

Preventative Measures: Fox scats are surprisingly persistent in the field and sufficient DNA is contained within scats for 100% accuracy in species identification, even after three months of weathering. DNA-based species identification is robust, no matter what method is used to extract DNA (Berry et al. 2007). DNA extraction with the commercial kit was the most costly (about AU$6.0, Euro 3.6, US$4.4 per sample in consumables) and time-consuming aspect of scat processing (compared with less than AU$0.10 per sample for chelex). Use of a cheaper and more straightforward extraction protocol places fewer constraints on the number of scats that could be processed.

Physical: Exclusion fencing is used to protect areas of high conservation value (Algar & Smith 1998, in Robley et al. 2007). It has proven to be a valuable tool in aiding the re-introduction of species to areas from which they have been previously eliminated by feral animals such as foxes (Robley et al. 2007). Results from fencing trials by Robley and colleagues (2007) indicate that fences should be 1.8 m high, have an overhang that is at least 600 mm in circumference that is curved or shaped in such a way that prevents animals climbing over from underneath, and have an apron with a mesh hard enough to prevent foxes chewing through. Electric fencing is not required.

Chemical: In Australia the fox is most commonly managed by setting baits impregnated with 1080 (sodium fluoroacetate) poison (Gentle et al. 2007). Fox numbers are controlled by laying dried meat baits containing the poison 1080 (sodium monofluroacetate) at least four times per year. The poison is a naturally occuring substance found in native plants called gastrolobiums or 'poison peas'. While native animals have evolved with these plants and have a high tolerance to the poison, introduced animals do not. Baits consist either of fresh or dried meat, offal, chicken eggs or commercial mixtures (Saunders & McLeod 2007, in Glen et al. 2007). Baiting is the only method currently available for predator control that can be used successfully over broad areas (Gentle 2005, in Glen et al. 2007). However, the long-term effectiveness of such control campaigns is likely to be limited due to the ability of foxes to disperse over considerable distances and to swiftly recolonise areas (Gentle et al. 2007). In southeastern Australia, baiting for foxes by landholders is encouraged by state government agencies. However, for reasons including bait caching and bait degradation, current baiting practices may not always be efficient or effective (Gentle et al. 2007). Managers should adopt a approach which seeks to minimise potential risk to non-target individuals, while clarifying population-level effects through continued research (Glen et al. 2007).

Fertility regulators include cabergoline, a dopamine agonist that has previously been demonstrated to have an abortifacient effect in cats (Felis catus) and dogs (Canis familiaris) (see Marks et al. 1996). Marks and colleagues (1996) report that the chemical is palatable to foxes and easily incorporated into a non-poisonous bait. The incidence of cubs was significantly lower in treatment dens than in the controls.

Vos (2003) reports that as a result of oral vaccination of foxes rabies has almost been completely eradicated from Western and Central Europe.