The European fox, Vulpes vulpes, was introduced into Australia in the early 1870s for recreational hunting purposes. The spread of the fox closely followed the distribution of rabbits across mainland Australia. Today, foxes are found in most areas of the mainland south of the tropics and, unfortunately, are even believed to have been deliberately released in Tasmania.
Foxes cause environmental damage, by preying on many species of Australian native wildlife. Foxes include birds, small mammals and reptiles in their menu. The extinction or endangerment of native wildlife is a national disaster. Foxes significantly contribute, alongside other vertebrate pest species and the impact of man, to the extinction pressures. Effective fox control has been shown to reduce the extinction pressure and to allow population recovery.
Serious economic damage results from fox predation on farm livestock , including lambs, calves, poultry, water fowl and goats. With a typical fox density about 4 foxes per 400 hectare (1000 acres), each fox will eat about 400 grams a night, or a little over a tenth of a tonne of food in a year. Overall, about a third of this diet is from farm livestock, a third from pest vertebrates like rabbits and mice, and a third from wildlife. However, foxes are opportunistic and if lambs are available they will make up 100% of the diet. Predation on other pest vertebrates does not provide effective control for these pests, because, unlike native animals, rabbits and mice can breed faster than the foxes can eat them.
In uncontrolled areas, foxes have been shown to cause lamb losses of 10% to 30%. Under extreme conditions, predation on lambs can be as high as 50%. Fox predation has also been reported on calves, cows in birth difficulty, deer, ostrich and emu chicks, and free-range poultry.
The national cost of direct fox predation of lambs is estimated at more than A$100 million annually.
If lamb marking in a 500ha farm increases from a typical figure of 80% to nearly 100% (i.e. 100 lambs marked per 100 ewes mated), as has been shown in the field, then the gross return to the farmer could be 20 to 50 times the investment in a fox control programme.
Foxes breed once a year in late winter. Breeding females wean about four cubs. Every summer, young foxes disperse to find new territories an may move up to 30km away from their natal dens. Typical fox family "home range" is from 30-1,000ha but individuals can make excursions of more than 10km.
Natural death rates are high, so most foxes are no more than one or two years old.
The adult fox weighs 5 to 7kg. It has excellent sight, smell, and hearing for skilled hunting. Foxes also possess canine teeth, speed, agility (including limited climbing ability) and wide dietary adaptability.
As all foxes require similar food inputs, the role of "rogue" foxes in predation is probably overstated: all foxes are predatory. The fox is one of the most successful predators in the world, and poses an enormous threat to Australia's fragile ecosystems.
Integrated fox control measures are more difficult than for many other species because foxes migrate further, and are more likely to re-infest previously controlled areas from distant uncontrolled areas. Also, fencing and harbour destruction are not practical options for fox control.
Den destruction is not as profitable as it is for rabbits, because the foxes will quickly make new dens. Therefore den destruction has little impact on fox numbers.
Used at breeding time, humane fumigation of dens with DEN-CO-FUME® carbon monoxide cartridges may be used in semi-urban areas to kill cubs.
A baiting programme using FOXOFF® Fox Baits and Econobaits twice a year, with bait replacement until the take is reduced, is an effective and environmentally conscious form of fox control in most rural areas.
Fox-proof fencing is effective for small areas only. Fencing is an expensive option, costing up to $20,000 per km, and requiring regular maintenance.
Shooting foxes is helpful, but it is likely to only remove a small proportion of foxes. Only those foxes that are easily seen, are shot. Spotlighting usually underestimates the fox population.
Biological and chemical fertility control measures are being considered, but it will be many years before this form of fox control will be a viable, large-scale control method. There are no suitable specific diseases that can be used for fox control or to carry a vaccine control agent.
Animal Control Technologies
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Somerton, Victoria, 3062
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