European Rabbit (Oryctolagus cuniculus)
History and distribution
The rabbit originated in Spain and southern France and domesticated rabbits arrived in Australia with the first fleet. The first feral populations were in south-eastern Tasmania where they numbered in the thousands on some estates by 1827. Thomas Austin, a member of the Victorian Acclimatisation Society, released 24 rabbits he had brought from England onto his property near Geelong for sport hunting on Christmas Day, 1859. By 1886 rabbits had spread north as far as the Queensland – New South Wales border and by 1900 they had reached Western Australia and the Northern Territory. The rate of spread of the rabbit in Australia was the fastest of any colonising mammal anywhere in the world and was aided by the presence of burrows of native species and modifications to the natural environment made for farming. Rabbits are now one of the most widely distributed and abundant mammals in Australia.
Rabbits have high reproductive potential. They breed from 3-4 months of age, give birth to litters of 4-7 young and a mature female rabbit can be continuously pregnant for 6-8 months per year under favourable conditions. A single pair of rabbits can produce 30-40 young a year.
The key to the success of the rabbit in Australia is the warren, which provides protection from weather and predators and enables rabbits to inhabit semi-arid and arid country. Rabbits will also readily live above ground whenever there is adequate shelter.
Some diseases and parasites of rabbits are absent in Australia and the generally dry climate constrains the parasites that are present. Compared with Europe and America, Australia has few predators and lacks wild mustelid species (e.g. ferrets and weasels), which kill young rabbits in warrens.
Rabbits are Australia’s most widespread and destructive environmental and agricultural vertebrate pest. Impact on agricultural production is greatest in drier areas where pasture production is low and rabbits can increase to high densities and compete with stock. In higher rainfall areas, rabbits can be more easily managed.
The impact of rabbits on native plants includes damage to vegetation through ringbarking, grazing and browsing. Rabbits also prevent regeneration of native plants by eating seedlings. As well as causing detrimental habitat change, rabbits threaten native mammals through direct competition for food and shelter and indirectly through intensified predation by cats and foxes after rabbit numbers crash during droughts or outbreaks of RHD (rabbit haemmorhagic disease or calicivirus) and myxomatosis .
Overgrazing by rabbits removes plant cover and contributes to soil erosion. Rabbits cause changes in the quality of flora and habitat of native fauna. Most rabbit damage to native vegetation occurs when the annual pasture dries off and rabbits are forced to eat native perennial plants.
Prior to the introduction of myxomatosis, efforts to manage rabbit populations were generally misdirected or inefficient. Poisoning, fencing and various forms of biological control were tried with little success.
The reduction of rabbits to low numbers has mostly been due to a combination of myxomatosis, rabbit haemorrhagic disease virus, introduction of the European rabbit flea, and changes to the environment. Another important contributing factor has been the improvement in strategic use of 1080 poison. As rabbits do not dig new warrens readily, an effective and long-term form of rabbit management is usually through destruction of warren networks with rippers mounted on tractors and bulldozers.
After the introduction of myxomatosis in 1950, rabbit numbers fell by about 95% in most of southern Australia and by almost 100% in marginal habitats. On average, present rabbit densities in Australia may be about 5% of pre-myxomatosis densities in the higher rainfall areas and perhaps 25% in the rangelands, however populations tend to fluctuate greatly due to changing conditions and drought.
While myxomatosis and rabbit haemorrhagic disease have been used in the past to control rabbits, over time rabbits develop resistance to these diseases and new methods of control will be required.