Interesting Facts

How European Rabbits Took over Australia

In 1859, wealthy settler Thomas Austin released 13 wild rabbits on his Australian estate. By 1920, their population grew to 10 billion.

Since the late 19th century, when European rabbits were first brought to Australia, there has been an issue with them. Currently, Australia is thought to be home to 200 million feral rabbits.

Australia’s introduction of European rabbits

In order to facilitate hunting, European rabbits (Oryctolagus cuniculus) were brought into the Australian bush in 1859. Thirteen European wild rabbits were sent to Thomas Austin, an affluent settler in Victoria, Australia, and he allowed them to roam freely on his estate. It only took these invasive (i.e., non-native to the land) rabbits 50 years to spread across the entire continent from this one backyard sanctuary.

Since these conditions are fairly easy to come by, they can adapt to new habitats such as the deserts and plains of Australia as easily as the meadows of Europe.

Their population grew to such an extent that they destroyed land and crops, causing soil erosion. By overgrazing, they also had a detrimental effect on plants and agriculture. The rabbits not only destroyed Australian crops, but they also played a part in the extinction of local animal and plant species. The primary environmental law of the Australian government, the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, even identifies the many impacts of feral rabbits, like land degradation, as a “threatening process.” The remarkable adaptability of these rabbits has contributed to their dispersal throughout the Australian continent. All the rabbits require are short grasses to graze on and soil suitable for burrowing.

European rabbits are not only adaptive animals, but they also have a reputation for procreating quickly and in large numbers. They are capable of reproducing year-round and at an early age. European rabbits, also known as hares, typically have two to five kits (baby rabbits) per litter and can produce more than four litters annually.

How to Handle Invading Rabbits

To eradicate Australia’s invasive rabbits, biologists, farmers, government researchers, and others have tried. Many strategies, such as fences, poisons, and infections, have been tried by experts to control rabbit populations; some have shown to be more effective than others.

After coming to Australia a few decades ago, rabbits started to pose a serious threat to farmers. In the beginning, fences were constructed by the government and farmers to prevent the rabbits from damaging their crops. In fact, the government hired builders to erect a fence that connected the north and south of Western Australia. Fencing didn’t really stop the rabbits, though. In the case of the fence in Western Australia, it only contained rabbits that were already residing there.

In an attempt to manage the population, farmers have also been known to destroy rabbit warrens, which are underground networks of tunnels. The area where rabbits can safely breed and raise young is taken away when the warrens are destroyed. Today, farmers continue to use the warren destruction method, which is effective for controlling rabbit populations found on accessible lands.

The government started using biocontrol in the 1950s. In southeast Australia, they dispersed rabbits infected with the virus known as myxoma, which is unique to rabbits. The first virus to be intentionally released into the wild with the intention of eradicating an animal was the myxoma virus. The myxoma virus causes myxomatosis, a disease that only kills rabbits, and Australian scientist Peter Kerr said of this release, “Thus, inadvertently, began one of the great experiments in natural selection, conducted on a continental scale.” Many rabbits in Australia did die from the myxoma virus, but over time the rabbits developed an immunity to the virus, making it useless. The scientists would have to try a different approach if they were to successfully eradicate these invasive rabbits.

Another pathogen that is unique to rabbits is Rabbit Hemorrhagic Disease Virus (RHDV), which researchers first described in the 1980s. This illness, which is brought on by an RNA (ribonucleic acid) virus spread by flies, can kill rabbits within 48 hours of infection. This virus broke free from a quarantine facility in 1995 and entered the wild. In particularly dry areas, RHDV reduced rabbit populations in Australia by up to 90% after it was formally released in 1996 with the goal of controlling the population. European rabbits that reside in cooler, more rainy regions of Australia are immune to the disease because flies act as the virus’s vector. Similar to the myxoma virus, these rabbits are starting to show signs of resistance against RHDV.

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Poison proved to be another popular population-control strategy for European rabbits, in addition to viruses. With a death rate of over 90%, sodium fluoroacetate is one of the primary chemicals used to poison rabbits. In order to fumigate burrows and eliminate any rabbits residing within, phosphine and carbon monoxide are also utilized.

Virus introduction into the wild appears to be the most efficient and economical method of reducing the population of European rabbits. Scientists are still trying to manage these mammals’ populations to prevent habitat destruction in Australia. More lethal RHDV strains that might be even more successful in keeping the rabbits from overrunning the Australian environment are currently being researched by researchers. Since the European rabbits are an invasive species, and are extremely disruptive to the local environment, finding a solution to rein in and control their populations is imperative.

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