Rabbits in Australia
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In Australia, rabbits are the most serious mammalian pests, an invasive species, and are responsible for the extinction of about as many native animals as the fox. Annually, European Rabbits cause millions of dollars of damage to agriculture.
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[edit] Effects on Australia's ecology
The effect of rabbits on the ecology of Australia has been devastating. One eighth of all mammalian species in Australia are now extinct (rabbits are the most significant known factor), and the loss of plant species is unknown even at this time.
Rabbits are also responsible for serious erosion problems as they eat native plants which would have retained soil. Some of this erosion may also be the result of settlers clearing much of Australia's land for farming and housing.
[edit] Introduction of rabbits to Australia
Rabbits were first introduced to Australia by the First Fleet in 1788, but the current infestation appears to have originated with the release of 24 wild rabbits by Thomas Austin on his property, Barwon Park (near Winchelsea, Victoria), in October 1859 for hunting purposes. While living in England, Austin had been an avid hunter, regularly dedicating his weekends to rabbit shooting. Upon arriving in Australia, which had no native rabbit population, Austin asked his nephew in England to send him 24 grey rabbits, five hares, 72 partridges and some sparrows so that he could continue his hobby in Australia by creating a local population of the species. Many other farms released their rabbits into the wild after Austin.
Rabbits are extremely prolific creatures, and spread rapidly across the southern parts of the continent. Australia had ideal conditions for a rabbit population explosion. With mild winters, rabbits were able to breed the entire year. With widespread farming, areas that may have been desert, scrub, or woodlands were instead turned into vast areas with low vegetations, creating ideal habitat for rabbits. Humans were directly responsible for the initial release of the rabbits, and indirectly responsible for modifying the Australian landscape for ideal rabbit survival.
Within ten years of the 1859 introduction, the original 24 rabbits had multiplied so much that two million could be shot or trapped annually without having any noticeable effect on the population.
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 country, with scattered populations in the northern deserts.
[edit] Rabbit control measures
Currently, land owners are legally bound to control rabbits in order to reduce their impact on the land and local flora and fauna. In fact, rabbit eradication campaigns have become a popular pastime in the country's rural areas. Control measures generally include killing them, fertility control, or exclusion, but most of these rabbit control measures have had an insignificant impact on the rabbit population.
The Rabbit-proof fence was built in Western Australia, between Cape Kerundun and Esperance to try to control the rabbit population. European rabbits can both jump very high and burrow underground, even assuming a perfectly intact fence stretching for hundreds of miles, and assuming that ranchers or farmers don't leave gates open for livestock or machinery.
[edit] Conventional control measures
Shooting rabbits is reasonably common. Poisoning is also often used. Poisoning is probably the most widely-used of the conventional techniques, as it requires the least effort. The disadvantage is that the rabbit cannot be used as food for either humans or pets afterward.
Another technique used occasionally is hunting using ferrets, where nets are placed over burrow exits and the ferrets deployed to chase the rabbits into the nets. This is more a hunting activity than a serious control method.
Historically, trapping was also frequently used; steel-jawed leg-holding traps were banned in most states in the 1980s on animal cruelty grounds, though trapping continues at a lower level using rubber-jawed traps. All of these techniques are limited to working only in settled areas and are quite labor-intensive.
[edit] Biological measures
Releasing rabbit-borne diseases has proven somewhat successful in controlling the population of rabbits in Australia. In 1950, Myxomatosis was deliberately released into the rabbit population which caused the rabbit population to drop from an estimated 600 million to around 100 million. Genetic resistance in the remaining rabbits allowed the population to recover to 200-300 million by 1991.
To combat this trend, Commonwealth Scientific and Industrial Research Organization (CSIRO) scientists released rabbit calicivirus (also known as Rabbit Hemorrhagic Disease or RHD) in 1996. However, it was not as successful as myxomatosis in part because it was estimated to have been fatal to only 65% of infected rabbits, as opposed to 99% for myxomatosis.
The Australian Government refuses to legalize a vaccine to protect pet rabbits against Myxomatosis (a legal vaccine exists in Australia for RHD), and thousands of pet rabbit owners in Australia suffer losses of their pet rabbits each year. There is no cure for either Myxomatosis or RHD, and many affected pets are euthanized. In Europe, where rabbits are farmed on a large scale, they are protected against myxomatosis and calicivirus with a genetically modified virus. The virus was developed in Spain, and is beneficial to rabbit farmers. If it were to make its way into wild populations in areas such as Australia, this could create a population boom.
[edit] See also
[edit] External links
- Rabbit Information Service - a site opposing the use of rabbit calicivirus in Australia
- Dr Brian Cooke from CSIRO Wildlife and Ecology receiving the 2000 POL Eureka Prize for Environmental Research, for his lifetime commitment to reducing the devastation caused by rabbits on the Australian environment
