"Most of the strains circulating now kill about 40 per cent of rabbits that are infected," says Mutze. The virus' toxicity has also reduced over time. In arid areas, where mosquitoes cannot survive, myxomatosis did not spread well. However, with the virus spread by mosquitoes, fatality rates varied across the country. In some areas 99 per cent of the rabbits were killed. Initially, myxomatosis caused enormous reductions in rabbit numbers. Most rabbits die of haemorrhage and seizures within 10 days. The mucus accumulates under the rabbit's skin, leading to internal swelling. Once infected, the rabbits develop lesions filled with mucus. Myxomatosis, the disease caused by the Myxoma virus, occurs naturally in South American cottontail rabbits. So in 1950 the biological control agent, Myxoma virus, was introduced to Australia's mainland. However, conventional controls are labour intensive and time consuming and, faced with the rate at which rabbits breed, cannot hold down numbers on their own. "Using poison, deep ploughing and then fuming burrows was highly cost effective reducing rabbit numbers," says Mutze. Myxomatosis didn't stop Australia's rabbit problem as this photo taken near Adelaide in 1961 shows.Ĭonventional and biological controls have been used in Australia to eradicate rabbits.Ĭonventional controls include destroying rabbit burrows with poison and fire. The rate at which bunnies breed doesn't help either a single female rabbit is able to produce between 18 and 30 young per year. While increased rabbit sightings tell us that numbers are on the rise, accurate estimates of Australia's rabbit population today are difficult to make because there is no national reporting and mapping system.
Rabbits also threaten some of our native burrowing animals, such as the bilby and the burrowing bettong, by moving into their existing burrows and competing for food. "Rabbits are very good at finding the seedlings of shrubs when they are very small and grazing them out to the extent where the native shrubs are completely unable to regenerate," says Mutze. They have adapted to Australia's diverse environments, establishing themselves in farmland, deserts, grasslands and wet coastal plains, and causing havoc to native flora and fauna. Unfortunately the fences were a flop because rabbits had already moved into the areas being fenced off.īy the 1920s, Australia's rabbit population had swelled to 10 billion.Ĭurrently, rabbits inhabit around 4 million square kilometres of Australia, stretching from southeast NSW to the WA wheatbelt. To prevent the rabbits' westward spread, the WA government finished building three rabbit-proof fences across the state in 1907. In 1886 rabbits were spotted in South Australia and Queensland, and by 1890 were hopping across eastern Western Australia. Rabbits spread throughout Victoria and by 1880 had crossed into New South Wales. "It was hoped that they would flourish so that the owners could hunt them."įlourish they did. "Rabbits were introduced as part of a broad attempt by early colonists to make Australia as much like Europe as they possibly could," says Greg Mutze, research officer at the Department of Water, Land and Biodiversity Conservation in South Australia. "You could compare to a golf course," says Dr Arko Lucieer from the University of Tasmania, co-author of a recent paper published in the Journal of Applied Ecology analysing the effect of the growing rabbit population on the island.įaced with a bunny explosion across the country, scientists are urgently looking for solutions to eradicate this ecological nightmare.Įuropean rabbits first arrived in Australia with the First Fleet in 1788, but they only became a pest after 24 wild rabbits were released for hunting near Geelong in Victoria 150 years ago. Here, rabbit numbers have swelled from under 20,000 to 130,000 in only six years, and have eaten much of the native bushland. The latest battlefront is Macquarie Island, a subantarctic island halfway between Australia and Antarctica. Rabbits have been spotted in rising numbers in the Atherton tablelands in far north Queensland, and the Northern Rivers region in New South Wales.
Gardeners and growers everywhere, watch your lettuce patches! Australia is being hit by a bunny invasion and these marauders aren't the chocolate kind.Īfter years of battling this pest, Australia is now facing a fresh increase in rabbit numbers. Video: Scientists use web to capture rabbit numbers (ABC News).