Exotic Animals - Predators
The Red Fox - Vulpes vulpes
The red fox is native to Europe, Asia and North America. It was introduced to Victoria between 1855 and 1871. Foxes probably reached the Northern Territory between 1920 and 1930. The spread of foxes across Australia was closely linked to that of rabbits (Oryctolagus cuniculus) and today the distributions of both species largely coincide. In the Northern Territory, foxes are largely confined to the more arid areas south of a line extending east-west through Tennant Creek. The area between Tennant Creek and Alice Springs appears to have been permanently colonised only in the past 15 years.
Like feral cats, foxes are nocturnal, shy and elusive which makes it difficult to assess population abundance. Population density is dependent on prey availability and fox numbers are highest in high density rabbit areas. Fox densities of between 0.6 and 2.0 per square kilometre have been recorded in the arid and semi-arid rangelands of Australia.
The fox is a generalist and opportunistic predator and scavenger. There is increasing evidence that predation by foxes is a major threat to many species of native fauna. Scientific studies in Western Australia have shown that foxes have a major impact on existing populations of black-footed rock wallabies (Petrogale lateralis), brush-tailed bettongs (Bettongia penicillata), numbats (Myrmecobius fasciatus) and tammar wallabies (Macropus eugeni). Populations of all these animals increased following intensive fox control. Similarly, in New South Wales, malleefowl (Leipoa ocellata) survival has been shown to increase following fox removal. In the Northern Territory, one of the two last known wild populations of the mala was exterminated by a fox.
Several mainland reintroduction programmes for native fauna have been thwarted by foxes. Perhaps the best example is that of the parma wallaby (Macropus parma) at a site in eastern New South Wales. In the Northern Territory, fox predation was a factor in a failed attempt by the Parks and Wildlife Commission to reintroduce bilbies (Macrotis lagotis) to Watarrka National Park. It is highly likely that foxes pose a major threat to the survival of remaining wild populations of the bilby in the Northern Territory.
Little is known of the competitive impacts of foxes on native fauna. Preliminary results from research conducted in Western Australia indicate that the density of the chuditch (Dasyurus geoffroii) increases following 1080 poisoning of foxes.
Foxes are a significant agricultural pest. In some sheep growing areas, fox predation may account for up to 30% of lamb deaths. Recent observations suggest that foxes may also have an impact on cattle in some areas, particularly on calves and calving cows. Foxes also prey on poultry and emu (Dromaius novaehollandiae) and ostrich (Struthio camelus) chicks which is of concern to some commercial operators.
The potential role that foxes could play in spreading exotic diseases like rabies if ever they were introduced to Australia is of major concern to health and agricultural authorities.
Poisoning using 1080 is effective and currently is the only method suitable for broadscale control of foxes. Foxes will readily dig up buried baits so the practice of burying baits is a good way to lessen impacts on non-target species like the dingo which are also susceptible to 1080.
Broadscale fox control has not been conducted in the Northern Territory. However, in 2002 a long-term fox control program will be implemented on Watarrka National Park in an effort to recover populations of the black-footed rock wallaby.
