Australia is an immense island, about twenty times larger than Spain, which, due to its condition as an isolated continent, offers newly arrived species great biological opportunities. But this I didn’t know Thomas Austin (1815-1871), an English settler, who in 1859 imported two dozen rabbits wild in England and released them for sport hunting on his farm in Victoria.
The British could not imagine in those moments in which that ‘innocent action’ would end. Its effect was devastating, in just three months the rabbits had spread over more than two thousand kilometers.
Austin was a very meticulous person and in his diary he recorded in great detail his agricultural, hunting and livestock activities. Thanks to this diary, we can know that seven years after freeing the rabbits, he killed 14,253, that is, an average of 39 rabbits per day.
Having no natural predators on the continent, those twelve initial pairs of rabbits multiplied in a very short time, becoming a veritable plague that endangered ecosystems.
One of the first measures adopted by the Australian government to curb the invasive species was to import natural predators that did not exist until then on the continent, specifically the Red fox. However, these animals soon realized that it was easier to catch a koala than a rabbit, so these marsupials were about to become extinct.
Fence of 1,700 km
In 1900 the authorities went a step further by raising a 1,700 kilometer fence to prevent the passage of rabbits to the western part of the island. A method that, unfortunately, also failed.
It is estimated that in the twenties of the last century there were already some 10 billion rabbits wild expanded throughout the island.
Three decades later, the Australian government again changed its strategy to control the plague, substituting hunting for biological warfareby importing a disease that killed South American rabbits.
At the end of the 19th century, it had been discovered in Uruguay the mixomatosis, an infectious disease caused by a virus – myxoma – that affects rabbits causing death. This disease is transmitted by the bite of insects that feed on blood, fleas and mosquitoes, that is, by hematophagous vectors.
Death by myxomatosis is horrible, infected animals suffer skin nodules in the area of infection, swelling of the face and genitals, shortly after they stop eating and finally die around ten days after contracting the infection. infection.
In 1950 this virus was successfully tested in parts of Australia and later it was used throughout the country. It is estimated that tens of millions of rabbits succumbed to myxomatosis. However, over time the rabbits developed immunity against the pathogen, so the population picked up again.
Hemorrhagic virus, new solution
In 1995, researchers on Wardang Island (Australia) experimented with a virus that spread a hemorrhagic disease, a microorganism that decimated up to 60% of the Australian wild rabbit population. According to the data published by scientists, it is a virus as contagious as the human flu and as deadly as Ebola. In 2017, the government used a new variant – the RHDV1 K5 strain – a virus that carries a hemorrhagic pathogen discovered in South Korea.
Nonetheless, the plague is not controlled and right now in some parts of Australia, such as Queensland, keeping or selling rabbits is considered a criminal practice punishable by up to six months in jail and a fine of $44,000.