Fox’s are in the top 6 most invasive species in Australia. They are highly intelligent and prolific breeders with a vixon (female) producing up to 5 cubs per year and are a significant biosecurity treat particularly if a major disease were to enter Australia

History of spread

Foxes were introduced to Australia for hunting purposes during the mid-1850s, with most releases being around Melbourne.

Only 20 years after their introduction, foxes were declared as a pest species in Victoria. Within 100 years, foxes had reached their current distribution on the Australian mainland. Today foxes occur over 75 per cent of Australia and their range is strongly linked with that of rabbits.

While there are 21 different species of fox throughout the world, only the red fox is found in Australia. Foxes may travel up to 10 to 15km per night but often rest in hides during the day. These hides include hollow logs or trees, enlarged rabbit burrows or dense undergrowth.

Economic impact

The economic impact of foxes in Australia has been estimated at around $227.5 million per annum. This includes: $17.5 million in sheep production losses $190 million in environmental impacts $16 million in management costs $4 million in research costs.

If rabies entered Australia, the impacts would be devastating for native animals and domestic livestock. Foxes, which are known vectors of rabies in different parts of the world, could significantly contribute to its spread if it were ever introduced. While it is a disease that mostly affects members of the dog family, it can also be passed on to humans, livestock and native animals.

Behaviour

Foxes are mainly nocturnal (night-time) hunters, being most active from dusk until dawn. They also occupy well-defined home ranges that are marked with scents including urine, droppings and anal gland secretions. In addition, foxes display territorial behaviors such as confrontation (aggressive and non-aggressive) and vocalisations. Foxes also cache (bury) food to eat later, which is a basic survival strategy. Foxes have few natural predators in Australia, with most mortality occurring because of humans or drought. Fox cubs are vulnerable to birds of prey and dogs.

Foxes have long, sharp teeth and very quick reflexes. Foxes cause significant distress and hardship when they kill livestock such as poultry and lambs. They kill by inflicting multiple bites around the head and neck. Birds such as poultry may only have the head and neck eaten, large feathers are chewed off rather than plucked out. Relatively large prey such as lambs typically have their tail, ears and tongues eaten and often the chest cavity is opened to eat internal organs. If the skin around the neck is cut back many small holes may be evident as a result of fox kill. Lambs and calves sometimes have their tongues eaten by foxes and sheep or cows can have teats or vulvas chewed off.

Diseases

Urban foxes have access to greater diversity and abundance of human food waste, and as a result, have a greater exposure and possible resistance to diseases that may infect their rural counterparts. Some of these diseases may also infect humans and domestic animals, including dogs and can be painful/fatal if left untreated such as:

• sarcoptic mange (mites),

• hydatids (worms),

• leptospirosis (bacteria).

Diet

Their diet is ANYTHING ranging from domestic livestock and native fauna, mice, insects, reptiles, frogs, birds, grain, vegetables including crops, fruit including blackberries. Primary predation by foxes on domestic livestock is common and those most susceptible include: poultry, new born lambs, goat kids, deer fawns, and even calves from a difficult birth. Common animal prey sizes at risk is anything up to 5.5kg. A single fox is estimated to eat about 400 grams of food each night. Over a year, this equates to around 150 kilograms of food. As foxes may kill many animals in a night, yet only consume a small amount of each, this could amount to thousands of mammals, reptiles, birds and insects killed each year by a single fox.

Reproduction

Vixens (females) mate once a year and will accept males over a 3-day period. Breeding is triggered by changing day length and food availability. In Australian, mating typically occurs over a 3-to-7-week period from mid-June to the end of July. Fox litters vary from three to five cubs. Pregnancy lasts for 51 to 53 days, and cubs are born in dens early August to late September. Cubs emerge from the den at around 6 weeks, and by 8 to 10 weeks they abandon the den and live on the surface.

At 3 months, cubs hunt for small animals and gradually gain independence by January or February. Although they may stay in their family groups, juvenile foxes become completely independent by March. Dispersal from the natal area occurs from March onwards when juvenile foxes are 6 to 9 months old. Young foxes are sexually mature by 9 to 10 months, with 85 per cent of young females breeding in the first year. Size can vary, males typically weigh 4 to 8 kg and females 4 to 6 kg.

Management

Control measures used for foxes include: baiting, harbour management where applicable, fumigation, shooting, trapping cage, trapping foot, exclusion fencing, animal husbandry, property hygiene. An integrated pest management approach that combines the use of all suitable control tools is best and be implemented in a coordinated manner at a landscape scale.

Fox control measures include trapping, shooting, den fumigation, and exclusion fencing. Poison baiting using 1080 is the most common method. Baiting can reduce fox activity by 50–97%, but the effectiveness is variable and foxes can recolonise rapidly.

(Source: Agriculture Vic & Invasives.org)