Rabbits in Australia
Rabbits in Australia are a serious mammalian pest and invasive species. Rabbits were introduced to Australia in the 18th century with the First Fleet, and became widespread after an outbreak caused by an 1859 release. Rabbits cause millions of dollars of damage to crops. Various methods in the 20th century have been attempted to control the population. Conventional methods include shooting and destruction of warrens, but these had only limited success. In 1907, a rabbit-proof fence was built in western Australia in an attempt to contain the rabbits. The myxoma virus, which causes myxomatosis, was introduced into the rabbit population in the 1950s, and had the effect of severely reducing the rabbit population.
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History [edit]
Rabbits were first introduced to Australia by the First Fleet in 1788. They were bred as food animals, probably in cages. In the first decades, they do not appear to have been numerous, judging from their absence from archaeological collections of early colonial food remains. However, by 1827 in Tasmania, a newspaper article noted "…the common rabbit is becoming so numerous throughout the colony, that they are running about on some large estates by thousands. We understand, that there are no rabbits whatever in the elder colony" [i.e. New South Wales].[1] This clearly shows a localised rabbit population explosion was underway in Tasmania in the early 19th century. At the same time in NSW, Cunningham noted, "... rabbits are bred around houses, but we have yet no wild ones in enclosures..." He also noted the scrubby, sandy soil between Sydney and Botany Bay would be ideal for farming rabbits.[2] Enclosures appear to mean more extensive rabbit-farming warrens, rather than cages. The first of these, in Sydney at least, was one built by Alexander Macleay at Elizabeth Bay House, "a preserve or rabbit-warren, surrounded by a substantial stone wall, and well stocked with that choice game."[3] In the 1840s rabbit-keeping became even more common, with examples of the theft of rabbits from ordinary peoples' houses appearing in court records, and rabbits entering the diets of ordinary people.
The current infestation appears to have originated with the release of 24 wild rabbits[4] by Thomas Austin for hunting purposes in October 1859, on his property, Barwon Park, near Winchelsea, Victoria. 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 William Austin in England to send him 12 grey rabbits, five hares, 72 partridges and some sparrows so he could continue his hobby in Australia by creating a local population of the species. However, William could not source enough grey rabbits to meet his uncle's order, so he topped it up by buying domestic rabbits. One theory as to why the Barwon park rabbits adapted so well to Australia is that the hybrid rabbits that resulted from the interbreeding of the two distinct types were particularly hardy and vigorous. Many other farms released their rabbits into the wild after Austin.
At the time he had stated, "The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting."[5]
The rabbits were extremely prolific creatures, and spread rapidly across the southern parts of the country. 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 scrub or woodlands were instead turned into vast areas with low vegetations, creating ideal habitats for rabbits.
In a classic example of unintended consequences, within ten years of their introduction in 1859, rabbits had become so prevalent 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.
Although the rabbit is a notorious pest, it proved useful to many people during the depressions of the 1890s and 1930s, and during wartime. Trapping rabbits helped farmers, stockmen and stationhands by providing something to eat and extra income, and in some cases helped pay off farming debts. Rabbits were fed to working dogs, and boiled to be fed to the poultry. Later, frozen rabbit carcases were traded locally and exported. Pelts, too, were used in the fur trade and are still used in the felt-hat industry.[6]
Effects on Australia's ecology [edit]
Since their introduction from Europe in the 19th century, the effect of rabbits on the ecology of Australia has been devastating. They are suspected of being the most significant known factor in species loss in Australia. The loss of plant species is unknown at this time. Rabbits often kill young trees in orchards, forests and on properties by ringbarking them.[6]
Rabbits are also responsible for serious erosion problems, as they eat native plants, leaving the topsoil exposed and vulnerable to sheet, gully and wind erosion. The removal of this topsoil is devastating to the land, as it takes many hundreds of years to regenerate.
Control measures [edit]
By 1887 losses from rabbit damage compelled the New South Wales Government to offer a substantial reward for "any method of success not previously known in the Colony for the effectual extermination of rabbits".[7] The offer attracted the attention of Louis Pasteur who proposed using the chicken cholera bacillus (now known as Pasteurella multocida), and while this measure was not proved practicable the association with Pasteur accelerated the introduction of microbiology into Australia.[8]
A Royal Commission was held to investigate the situation in 1901. Once the problem was understood, various control methods were tried to limit or reduce the population of rabbits in Australia. These methods had limited success until the introduction of biological control methods in the latter half of the 20th century.
Conventional control measures [edit]
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Shooting rabbits is one of the most common control methods and can successfully be used to keep already low populations in check whilst providing food for people or pets, though large scale eradication requires different means.
Destroying warrens through ripping (a procedure where rabbits are dismembered or buried alive as a bulldozer dragging sharp tines is driven over their warrens/burrows),[9] ploughing, blasting, and fumigating is widely used, especially on large farms (known as "stations"). The sandy soil in many parts of Australia makes ripping and ploughing a viable method of control, and both tractors and bulldozers are used for this operation.
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. Two commonly used poisons for rabbit control are sodium fluoroacetate ("1080") and pindone.[10]
Another technique is hunting using ferrets, where ferrets are deployed to chase the rabbits out to be shot or into nets set over the burrows. Since ferrets are limited in the number of rabbits they can kill,[citation needed] 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 labour-intensive.
Fence [edit]
In 1907, the rabbit-proof fence was built in Western Australia between Cape Keraudren and Esperance to try to control the spread of the rabbit population from the east into Western Australian pastoral areas. However since European rabbits can both jump very high and burrow underground, even assuming a perfectly intact fence stretching for hundreds of miles, and assuming farmers or graziers did not leave gates open for livestock or machinery, it was unlikely to be a success.
Biological measures [edit]
Releasing rabbit-borne diseases has proven somewhat successful in controlling the population of rabbits in Australia. In 1950, after research carried out by Frank Fenner, myxoma virus was deliberately released into the rabbit population, causing it to drop from an estimated 600 million[11] 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 Organisation (CSIRO) comprehensively tested, over three years from June 1991, the release of calicivirus to cause rabbit haemorrhagic disease (RHD).[12] The virus escaped from a quarantine compound on Wardang Island, South Australia, where field tests were being carried out on the potential of the virus for biological control of wild rabbits, and by late October 1995 it was recorded in rabbits at Yunta and Gum Creek, in northeastern South Australia.[13] By the winter of 1996, the virus was established in Victoria, New South Wales, the Northern Territory and Western Australia. The success of the virus was found to be higher in extreme heat, because it appears there is another calicivirus in the colder, wetter areas of Australia, and that this virus was immunising rabbits against the more virulent form.
A legal vaccine exists in Australia for RHD. There is no cure for either myxomatosis or RHD, and many affected pets are euthanised. In Europe, where rabbits are farmed on a large scale, they are protected against myxomatosis and calicivirus with a genetically modified virus.[14] The vaccine was developed in Spain.
See also [edit]
References [edit]
- ^ Colonial Times and Tasmanian Advertiser 22 May 1827
- ^ Cunningham P. [1827] Two years in New South Wales, vol. 1, p. 304
- ^ Sydney Gazette 28 May 1831
- ^ http://www.animalcontrol.com.au/rabbit.htm
- ^ "The State Barrier Fence of Western Australia". Retrieved 2008-05-30.
- ^ a b Australian Encyclopaedia, Vol, VII, Grolier Society, Sydney
- ^ "Advertising. - Extermination of rabbits.". The Sydney Morning Herald (NSW : 1842 - 1954) (Sydney). 7 September 1887. p. 11. Retrieved 21 July 2012.
- ^ Puls, Margaret, ed. (April 2006). "A microbial history of Australia" (PDF). Livestock Horizons (St. Lucia, Queensland: CSIRO Livestock Industries) 2 (2). ISSN 1832-3677. Retrieved 21 July 2012.
- ^ http://www.environment.gov.au/biodiversity/invasive/publications/pubs/rab006-rabbit-warren-destruction-ripping.pdf
- ^ Farrelly, Gary; Paul Merks and staff of Vertebrate Pest Research Services (2005), "Options for rabbit control" (pdf), Farmnote No. 89/2001 (Department of Agriculture, Western Australia), retrieved 1 February 2011
- ^ http://www.csiro.au/science/Myxomatosis-History.html
- ^ "Rabbit Calicivirus Disease (RCD)". CSIRO. Retrieved 29 November 2011.
- ^ Cooke, Brian D. (1997). Analysis of the spread of rabbit calicivirus from Wardang Island through mainland Australia. Sydney, NSW: Meat Research Corporation.
- ^ Horizontal Transmissible Protection against Myxomatosis and Rabbit Hemorrhagic Disease by Using a Recombinant Myxoma Virus
External links [edit]
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Wikimedia Commons has media related to: Rabbits |
- 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
- Australian Broadcasting Corporation Landline
- Australian Broadcasting Corporation Rabbiting On - Australian stories of experiences with the pest
- CSIRO Protection for Pet rabbits
- Culture Victoria – Nox All Rabbits video about rabbits and rabbit control in Australia
