The red fox is a small to medium sized, burnished rusty red coloured canid. Closely related to domestic dogs, the adult European red fox (Vulpes vulpes) weighs about 5 to 9 kg with males generally heavier than females and from 700 mm to 1000 mm in length including 300 mm to 350 mm of bushy red tail. The red fox is an athletic animal that can run, leap fences and with partly retractable claws, climb fences and some trees.
There are 11 species of fox worldwide, occurring naturally in North America, Europe, Asia and North Africa. The European red fox is the most widely distributed species and was introduced into many countries including Australia in 1845. In Australia, other successful releases followed in southern Victoria in the 1870's and within 20 years, the red fox had achieved pest status. The expansion of the red fox population across mainland Australia followed the spread of its favourite prey, the rabbit. Their distribution on mainland Australia may be still expanding northwards into the tropics, having reached the Tanami desert in late 1970's and now common around Tennant Creek in the Northern Territory. Foxes are limited by the heat and humidity of the tropics and the northern boundary probably fluctuates with the seasons.
Tasmania was the only state where foxes were not introduced or were unsuccessful possibly due to the more aggressive Tasmanian devil. The occurrence of the red fox in Tasmania remains controversial. Evidence of their presence on the island has been indicated by carcasses and scats although recent evidence suggests they have been eradicated. There is concern that the decline in Tasmanian Devil numbers due to disease may make it easier for any incursions of foxes into Tasmania to lead to an established fox population with associated impacts.
In NSW, the red fox is favoured by the fragmented landscapes common in all districts that provide shelter, food and den sites. Densities vary from around 1/km2 in the coastal forests, 2 to 5/km2 in the semi-arid and sub-alpine regions and 6 to 8/km2 in the temperate grazing lands that cover most of NSW. Populations of the red fox are well established in peri-urban and urban areas where food is abundant and densities may range from 12/km2.
The red fox is territorial and continuously marks its home range with urine, faeces and anal scent. Scent marking can be also be used during the breeding season to indicate reproductive status. Fox territories range from 2 to 5 km2 and vary with type of habitat, population density of foxes and availability of food. During the breeding cycle, dog (male) and vixen (female) foxes will form a family group prior to breeding and sometimes subordinate litter mates may remain in the natal home range as helpers. Foxes are defensive of their territory although it is common that home range boundaries overlap within and between the family groups in an area.
Females come into oestrus for 2 to 3 days over 2 to 3 weeks in winter. Males are fertile throughout winter and early spring. Gestation lasts 51 to 53 days and a litter of 3-5, blue-grey cubs is born in the den. Weaning occurs at 4 to 6 weeks by which time most of the grey colouring has gone.
The young appear from the den in late spring, at about 6 weeks of age. During this time daytime activity by adults feeding cubs is common. The cubs leave the den at about 10 to 12 weeks and by 6 months of age, are independent. Both sexes reach sexual maturity in their first year. Where there is low mortality in the family group, a proportion of the female population may not breed. These helper vixens may assist to raise the cubs. Once foxes are independent they begin to move or disperse out of the family group to find, establish and mark new territories. Most dispersal is within about 30 km, however, long distance dispersal of over 300 km is known to occur. The inherent ability of the red fox to rapidly establish new territories over short or long distances ensures they are perfectly adapted to compensate for any population decline due to control programs.
By day, the red fox usually rests in a hide, this may be a hollow log, tree, an enlarged rabbit burrow or dense undergrowth. By night they hunt and patrol their territory. The red fox is best described as an opportunistic predator and scavenger. Largely carnivorous, foxes eat a diet of 300 g to 450 g/day of small prey in the weight range of 5 to 15 kg, including native animals, birds, rabbits, house mice and carrion. They readily eat fruits such as wild blackberry and insects such as scarab or 'Christmas' beetles. When food is abundant, foxes will often bury or 'cache' excess food. When food is limited in winter, cached food may be recovered.
Fox predation is recognised as having a serious impact on many native animals, and is considered to be a major contributor to extinction of some species. Species impacted include: brush tailed and yellow footed rock wallabies, bettongs, numbats, mallee fowl, pied oyster catcher, little tern, plains wanderer, bush stone curlew and the Murray river turtle. There is also little doubt that foxes have an economic impact on sheep, goat, poultry and cattle enterprises. Fox predation is listed as a key threatening process in NSW and a Threat Abatement Plan (TAP) has been prepared.
Diseases such as distemper, parvo virus, sarcoptic mange and predators such as wild dogs, eagles and snakes have an influence in controlling the fox population, however, the greatest single mortality occurs with targeted control programs. Rabbit control programs may initially increase fox predation on other species because of the adaptability of foxes to switch to other prey sources when preferred food items decline. To avoid this potential prey switching, fox control should be integrated with rabbit control.
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