Rabbits in Australia
In their natural environment and in captivity, rabbits are a benign, even useful species. When introduced by humans into other environments that have not evolved natural defences against them, however, rabbits can cause enormous damage. The best known example is the continent of Australia.
Rabbits are the most serious mammalian pest in Australia, an invasive species being responsible for the extinction of about as many native animals as the fox, and causing millions of dollars worth of damage to agriculture each year. They were originally introduced with the First Fleet in 1788, but the major infestation appears to have been due to 24 wild rabbits released by Thomas Austin on his Southern Victorian property in 1859, for hunting purposes. Many other farms released their rabbits into the wild after Austin.
Austin probably had not been reading the Roman geographer Strabo, who gave the following account of feral rabbits introduced in the 2nd century BC into the Balearic Islands ("Gymnesiae"):
- "No injurious animal can easily be found in the Gymnesiae. For even the rabbits there, it is said, are not native, but the stock sprang from a male and female brought over by some person from the opposite mainland [of coastal Spain]; and this stock was, for a fact, so numerous at first, that they even overturned houses and trees by burrowing beneath them..." (III.5.2)
Rabbits are extremely prolific, and, in Australia, had no predators that could keep their numbers low. As a consequence, they spread rapidly across the southern parts of the continent.
Within ten years of the 1859 introduction, the original 24 rabbits had multiplied so fast that 2 million a year could be shot or trapped without having any noticeable effect on the population size. Rabbits reached the New South Wales border in 1870. Fifteen years later they entered Queensland, and by 1900 the rabbit was firmly established nationwide. It was the fastest spread ever recorded of any mammal anywhere in the world. Today rabbits are entrenched in the southern and central areas of the continent, with scattered populations in the northern deserts.
The effect on the ecology of Australia was devastating: One eighth of all mammalian species in Australia are now extinct (rabbits being the single most significant factor), and the loss of plant species will probably never be fully appreciated. Rabbits cause huge damage to the agricultural economy. They are also responsible for serious erosion problems, preventing native plant growth to the point of extinction, impacting biodiversity, and ruining gardens.
Nowadays, landholders are legally bound to control rabbits to reduce impact on the land and local life. They can attempt to control rabbits through death, fertility control or exclusion, but the only really significant checks in rabbit numbers have been biological. Myxomatosis was released into the rabbit population in 1950, causing estimated rabbit population to drop from 600 million to 100 million. Genetic resistance in the remaining rabbits led to the population recovering to around 200-300 million by 1991. To combat this trend, CSIRO scientists released rabbit calicivirus in 1996. However, it was not as successful as myxomatosis: it was estimated to have been fatal to only 65% of infected rabbits, as opposed to 99% for myxomatosis. [1] (http://www.csiro.au/communication/rabbits/rab2999a.htm) Rabbit eradication campaigns have become a popular pastime in the country's rural areas.
The rabbits now have such a bad reputation in Australia that a recent campaign was launched to replace the Easter Bunny with the Easter Bilby (a type of native marsupial).
Meat rabbit farming, also called cuniculture, is a minor industry in Australia. It provides income diversification for some farmers. Annual revenue has been estimated at $AUD 5.5 million (1990/91). [2] (http://www.csiro.au/communication/rabbits/qa1.htm)