An invasive species is a species occurring, as a result of human activities, beyond its accepted normal distribution and which threatens valued environmental, agricultural or other social resources by the damage it causes. Invasive species have a major impact on Australia's environment, threatening it's unique biodiversity and reducing overall species abundance and diversity.
CHARACTERISTICS Feral rabbits are night-time grazers, preferring green grass and herbs. They also dig below grasses to reach roots and seeds. During the breeding season, feral rabbits form territorial groups made up of one to three males with up to seven females, led by a dominant pair. After breeding, the groups break up again, except for the dominant pair. Feral rabbits can breed from the age of four months, and can do so at any time of the year, particularly when food is in good supply. In favourable conditions, they can produce five or more litters in a year, with four or five young in each litter. Even in unfavourable conditions, they can produce one or two litters a year.
HOW DID THEY GET HERE? Domesticated rabbits arrived in Australia with the First Fleet. The first feral rabbit population was reported in Tasmania as early as 1827. On the mainland, Thomas Austin freed about a dozen on his property near Geelong, Victoria, in 1859. They reached the Queensland – New South Wales border by 1886 and covered most of their present range by 1910. This was despite the Western Australian Government’s 1700 kilometre rabbit-proof fence, built between 1901 and 1907. Today, feral rabbits occur throughout Australia, except in the northernmost areas.
EFFECT ON THE ECOSYSTEM: Feral rabbits compete with native wildlife, damage vegetation and degrade the land. They ringbark trees and shrubs, and prevent regeneration by eating seeds and seedlings. Their impact often increases during drought and immediately after a fire, when food is scarce and they eat whatever they can. Feral rabbits may have caused the extinction of several small (up to 5.5 kilograms) ground-dwelling mammals of Australia’s arid lands, and have contributed to the decline in numbers of many native plants and animals. In the Norfolk Island group, feral rabbits and goats reduced Philip Island to bedrock, leaving at least two plants locally extinct. Feral rabbits even threaten colonies of seabirds such as Gould’s petrel.
STRATEGIES TO CONTROL THE RABBIT POPULATION: FENCING
Effective rabbit control requires integration of different methods; any single technique used in isolation is less effective than two or more techniques carefully combined. When reliance is placed on only one technique and follow-up control is not implemented, initial gains are lost as rabbits will readily recolonise in the absence of further control. Current techniques available for controlling rabbits can be categorised broadly as biological, chemical and mechanical. Biological control for rabbits has been particularly effective. Biological controls include the myxoma virus causing the disease myxomatosis, which only affects rabbits. Released in 1950, the virus initially killed over 90 per cent of feral rabbits that caught the disease, but some developed resistance, making the pathogen less effective. However, the myxomatosis disease still keeps populations to an average of five per cent of former population sizes in wetter areas, and 25 per cent in arid areas. The other important biological control is the rabbit calicivirus disease (rabbit haemorrhagic disease virus) which has proved more effective in wetter parts of the country than in drier regions. Australia currently has only one strain of calicivirus which is relatively stable and rabbits are developing genetic resistance to infection. Research is being undertaken to identify new field strains to release in Australia. The main chemical control used for rabbits is the poison; sodium flouroacetate (1080) an effective toxin providing a high mortality rate of up to 90 per cent. Pressure fumigation or diffusion fumigation using toxins like chloropicrin and carbon monoxide are used to kill rabbits while they are in their warrens. Rabbits reduced Phillip Island, NSW, to a wasteland (top) but recovery was spectacular after the rabbits were eradicated (bottom photo) (SEWPaC). Destruction of warrens and above-ground harbours is the most widely used mechanical method for rabbit control. Warren ripping can be a cost- effective and efficient method for suppressing rabbit numbers and inhibiting reinvasion of the treated area, because it deprives rabbits of a safe place for breeding. Other methods used less widely are fencing, shooting, trapping and explosives to destroy warrens. Researchers are also looking at ways to improve traditional feral rabbit control techniques, and to ensure that control is applied in a strategic way that achieves targeted, sustained results. There is a community expectation that all animals, including pests are to be treated humanely. Therefore, animal welfare issues must be an important consideration when planning rabbit control operations.
Rabbits In Australia
EUROPEAN RABBIT
An invasive species is a species occurring, as a result of human activities, beyond its accepted normal distribution and which threatens valued environmental, agricultural or other social resources by the damage it causes.
Invasive species have a major impact on Australia's environment, threatening it's unique biodiversity and reducing overall species abundance and diversity.
CHARACTERISTICS Feral rabbits are night-time grazers, preferring green grass and herbs. They also dig below grasses to reach roots and seeds. During the breeding season, feral rabbits form territorial groups made up of one to three males with up to seven females, led by a dominant pair. After breeding, the groups break up again, except for the dominant pair. Feral rabbits can breed from the age of four months, and can do so at any time of the year, particularly when food is in good supply. In favourable conditions, they can produce five or more litters in a year, with four or five young in each litter. Even in unfavourable conditions, they can produce one or two litters a year.
HOW DID THEY GET HERE? Domesticated rabbits arrived in Australia with the First Fleet. The first feral rabbit population was reported in Tasmania as early as 1827. On the mainland, Thomas Austin freed about a dozen on his property near Geelong, Victoria, in 1859. They reached the Queensland – New South Wales border by 1886 and covered most of their present range by 1910. This was despite the Western Australian Government’s 1700 kilometre rabbit-proof fence, built between 1901 and 1907. Today, feral rabbits occur throughout Australia, except in the northernmost areas.
EFFECT ON THE ECOSYSTEM: Feral rabbits compete with native wildlife, damage vegetation and degrade the land. They ringbark trees and shrubs, and prevent regeneration by eating seeds and seedlings. Their impact often increases during drought and immediately after a fire, when food is scarce and they eat whatever they can. Feral rabbits may have caused the extinction of several small (up to 5.5 kilograms) ground-dwelling mammals of Australia’s arid lands, and have contributed to the decline in numbers of many native plants and animals. In the Norfolk Island group, feral rabbits and goats reduced Philip Island to bedrock, leaving at least two plants locally extinct. Feral rabbits even threaten colonies of seabirds such as Gould’s petrel.
STRATEGIES TO CONTROL THE RABBIT POPULATION:
FENCING
Effective rabbit control requires integration of different methods; any single technique used in isolation is less effective than two or more techniques carefully combined. When reliance is placed on only one technique and follow-up control is not implemented, initial gains are lost as rabbits will readily recolonise in the absence of further control. Current techniques available for controlling rabbits can be categorised broadly as biological, chemical and mechanical. Biological control for rabbits has been particularly effective. Biological controls include the myxoma virus causing the disease myxomatosis, which only affects rabbits. Released in 1950, the virus initially killed over 90 per cent of feral rabbits that caught the disease, but some developed resistance, making the pathogen less effective. However, the myxomatosis disease still keeps populations to an average of five per cent of former population sizes in wetter areas, and 25 per cent in arid areas. The other important biological control is the rabbit calicivirus disease (rabbit haemorrhagic disease virus) which has proved more effective in wetter parts of the country than in drier regions. Australia currently has only one strain of calicivirus which is relatively stable and rabbits are developing genetic resistance to infection. Research is being undertaken to identify new field strains to release in Australia. The main chemical control used for rabbits is the poison; sodium flouroacetate (1080) an effective toxin providing a high mortality rate of up to 90 per cent. Pressure fumigation or diffusion fumigation using toxins like chloropicrin and carbon monoxide are used to kill rabbits while they are in their warrens. Rabbits reduced Phillip Island, NSW, to a wasteland (top) but recovery was spectacular after the rabbits were eradicated (bottom photo) (SEWPaC). Destruction of warrens and above-ground harbours is the most widely used mechanical method for rabbit control. Warren ripping can be a cost- effective and efficient method for suppressing rabbit numbers and inhibiting reinvasion of the treated area, because it deprives rabbits of a safe place for breeding. Other methods used less widely are fencing, shooting, trapping and explosives to destroy warrens. Researchers are also looking at ways to improve traditional feral rabbit control techniques, and to ensure that control is applied in a strategic way that achieves targeted, sustained results. There is a community expectation that all animals, including pests are to be treated humanely. Therefore, animal welfare issues must be an important consideration when planning rabbit control operations.
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