Fox Problems in Australia

Fox Distribution in Australia

Fox Distribution in Australia

Since their introduction into Victoria in the 1870’s, foxes have adapted well to the Australian environment and now infest almost all habitats except the far tropical north of the continent. Their range and density may still be increasing.

Environmental Impact

Foxes are highly effective predators and thrive by killing a great number of Australian native animals. Small mammals and ground nesting native birds are at special risk. Many species have become extinct due to the relentless predation pressure from foxes.

Fox with native bandicoot prey

Fox caught on remote camera with native Bandicoot prey. Courtesy Rob Hunt

Apart from their massive impact on wildlife and lamb production, foxes are known to spread weeds such as blackberries and olives via their scats.

Agricultural Impact

Foxes are also responsible for major economic losses of newborn lambs and goat kids. These predation losses can reach more than 20% of lambs born, so effective fox control programs commonly result in significant increases in marking rates.

Perhaps even more importantly, foxes carry and spread parasites, bacteria and viruses that affect working and pet dogs as well as native wildlife (mange, worms, distemper, hepatitis and parvovirus). Foxes would transmit rabies, should this virus enter Australia.

Understanding the fox problem

An important first step is to understand the true size of the fox problem.

Fox numbers

Results of a fox attack

Results of a fox attack

Most areas have between 1 and 4 foxes/Km2. Some areas, such as swamps or some periurban areas, can harbour even greater local densities in excess of 10/Km2.

Fox numbers in an area around a property

Fox numbers in an anrea around a property

At a density of 4 foxes/Km2, there may be hundreds of foxes within a 10 Km radius. A common error of fox managers is to seriously underestimate fox numbers and to use too few baits or not run a baiting program for sufficient time to achieve good levels of control.

Home ranges

Foxes have scent-marked home ranges where they spend most of their time. These can vary from 3 to 400 ha) but foxes are known to make sporadic transient forays of up to 10 Km outside their normal home ranges.

Foxes are exccellent predators

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.

They have a diverse diet that includes meat and plant items including fruits. They can spread seeds of pest plants like blackberries and olives.

Foxes are agile, can climb reasonably well and can travel a kilometre in just a few minutes.

Productivity benefits of control

Attack on a lamb

Attack on a lamb

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.

Fox reproduction

Fox eproduction cycle calander

Fox reproduction cycle calander

Foxes mate in late winter and give birth to about 4 cubs per female in spring, after a 5 week gestation. Fox cubs stay in natal dens for the first month or two of life then start to forage for food with parental assistance. In late summer the sub-adult cubs leave the parental location to establish their own territories. This is known as dispersal, when young foxes can move long distances to reinfiltrate any area of low fox abundance. Thus, control should be conducted on an annual basis, or more often if possible.

Fox cubs

Fox Cubs

Fox production rate

Fox density is estimated to be about 1 to 4 foxes/Km2. Therefore a state like Victoria (approx. 250,000 Km2) harbours up to 1 million foxes. Half are female and each female raises about 4 cubs/yr. The production rate is thus about 2 million new foxes per year.

Foxes have a high risk of failing in their first year of life. Only about half of the newborn foxes make it to one year old. The death rate continues at about 30% of each age group, each year, throughout the 5 year natural lifespan. Contrary to common opinion, most foxes are young and fewer than 10% of foxes reach 4 or 5 years old. All foxes can damage stock and wildlife. It is not just a “few old rogues” that need to be controlled.

Fox teeth and jaws are designed for killing.

Fox teeth and jaws are designed for killing.

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.

Buried baiting works well for foxes

Foxes naturally cache food and mark the sites of food caches by defecating or urinating nearby. This is not hiding of food, as other foxes can easily find and dig up the food. The buried baiting strategy simply mimics the natural behaviour of the fox. Even after a bait has been taken, other foxes will visit the site, so bait replacement during a program over several weeks is wise. A single bait round will not control all foxes in an area.

Good control programs.

  • Foxes should be controlled annually or twice annually, in programs over several weeks.
  • Establish bait stations throughout an area, not just in rings around lambing paddocks. Foxes will investigate all parts of their range quickly. Localisation of baits will leave areas where foxes have no bait exposure.
  • Highest fox numbers are in Autumn so this is a good time to bait young foxes from the previous breeding to prevent recruitment of animals into the next generation. Baiting in winter and into early Spring can destroy breeding females, so that four fewer cubs are born for the following season. Therefore both Autumn and winter/spring baiting programs are desirable. These times also provide maximum protection at the times vulnerable lambs and goat kids are born.
  • Since foxes can move rapidly, it is not wise to place baits close together as a single fox can find and take several baits. This is a waste of baits. Do not set up bait stations closer than 200m apart.
  • Bait replacement at a baiting site where a bait has been taken is good practice, as not all foxes will be killed in a single baiting round.
  • Work with neighbours to achieve depletion zones that are as large as possible for maximum protection of stock

Animal Control Technologies (Australia) Pty Ltd
46-50 Freight Drive
Somerton, Victoria, 3062
Australia
Telephone +61 3 9308 9688
Fax +61 3 9308 9622

E-mail: enquiries@animalcontrol.com.au