Image: Daryl Panther
Life cycle and reproduction
The average life span of a fox is three to six years, although individuals may live up to 10 years. Interstate studies show that around 70% of foxes in a population are less than two years old.
Foxes generally have only one mate, although social groups of one male to several females are known. Foxes are reproductively receptive once per year and are stimulated to breed by changing day-length and resource availability. Gestation is 51 to 53 days and most Australian cubs (also sometimes called 'kits') are born between August and September. Average litter size is four with up to 10 being possible. Cubs are weaned by about one month and are sexually mature by 10 months. They usually have well defined home ranges with spatially stable borders. Ranges vary in size depending on habitat and have been recorded at around 30 ha in urban areas and up to 1,600 ha in arctic environments. Dispersal is a common behaviour in sub-adult males from late summer through to breeding time in winter.
In Victoria, foxes generally pair up in early winter and mate in mid to late winter. They usually hide in shelters during the day. Foxes around the Port of Melbourne shelter in thick weeds such as blackberries and generally remain inactive until after midnight. Their activity increases gradually after midnight to reach a peak in activity from 1 am to 3 am. Data on these urban foxes suggest that first and second year animals do not generally disperse further than one to two km from their birth location.
The population estimate of the fox in Victoria is one to two million and in NSW is three to six million, with a common density of four to eight animals per square kilometre. It is estimated that one million foxes could potentially eat 400 tonnes of food per night or 146,000 tonnes of food per year. Research has shown that the 'typical' fox diet in Australia consists of one third native species, one third domestic stock, and one third feral pests such as rabbits, mice and rats. Of course, diet varies considerably from region to region and at different times of the year.
Foxes are opportunistic predators and scavengers, and will eat freshly killed meat, carrion, fruits, berries and even scraps from refuse sites. Any animal up to 5.5 kg may be taken as prey. In Tasmania this includes most of our native mammals as well as lizards, lambs, goat kids, rabbits, rats, mice, free-range poultry and wild ducks.
A single fox is estimated to eat about 400-800 g of food each night, which is roughly equivalent to one average sized bandicoot. Over a year, this equates to around 150-300 kg of food.
Foxes, like domestic dogs, 'cache' or bury surplus food for later consumption. Caching is usually no more than simply placing the food in a small hole or depression, then lightly covering it with soil, however some foxes will also use stumps or similar structures. If food availability decreases, the cached food will be used; if food levels remain high, the cached food is left and may be taken by other foxes or scavengers.
Foxes are generally solitary animals, except in the breeding season. They will maintain a well-defined home range with stable borders. Scent marking with urine, scats (droppings) and secretions from anal glands, plus aggressive and non-aggressive confrontations and vocalisations (calls) are all used to define the borders. Ranges vary in size depending on habitat and availability of food, and have been recorded from around 9 ha in urban areas up to 1,600 ha in Arctic environments.
Fox caught by motion camera in Victoria
Territories and activity
In general, foxes may be active from dusk, particularly after midnight through to dawn. They rarely travel more than 10 km per night within their home range but may revisit some sites within their home range several times a night. During the day they rest in dens or in sheltered sites such as stumps, hollow logs, or scrubby vegetation. A fox may use several resting sites within its home range and does not necessarily return to the same site each day.
Predators and competition
In Australia, foxes have few natural predators except for humans, dogs, dingoes and eagles. In Tasmania, there are a range of native carnivores, such as the Tasmanian devil, which have the potential to prey upon fox cubs.
Apart from predation and human actions (such as hunting and roadkill of foxes), fox deaths are thought to be mostly due to seasonal factors such as drought (and its impact upon food availability), mange and distemper.
Identifying Foxes - June 2012 (265 KB)