News that the Australian rabbit population is about to come under renewed deadly attack has produced varying reaction from landholders, hunters, animal lovers and wild produce gourmets. The latest weapon against our bunny is a sophisticatedly-armed biological tool known as RHDV-K5 – an improved strain of a former version of calicivirus (rabbit haemorrhagic disease, or RHD). This new deadly virus is due for release in autumn 2017. It will be offered in vial form to landholders deemed by authorised government personnel to be able and willing to participate in its use.
According to official reports, the Australian Pesticides and Veterinary Medicines Authority (APVMA) spent more than 18 months assessing the application of this biological agent, a Korean strain of the disease. There are high hopes for the new infection’s capability to deal a serious body blow to an imported animal long classified as a very troublesome pest.
More on the response to all this information in a moment, but some reflection is in order at this stage of our report.
Rabbits in Australia
History tells us that the English/European bunny became an inhabitant of our continent soon after the arrival of white settlers. In the days of sailing ships, rabbits were held in hutches below deck to provide meals during the long voyage to the New Continent. Records show that later, in 1859, a bloke named Thomas Austin brought out 24 rabbits, five hares and 72 partridges and released them just outside of Geelong in Victoria, at a property called Barwon Park on Christmas Day to remind him of his home away across the sea and to provide recreation for local hunters, as well as protein for those newcomers whose palates were not yet attuned to the flavour and texture of kangaroo meat.
Since then, farmers and landholders who followed in the footsteps of this nostalgic romantic cursed him as they spent incalculable time and resources trying to undo what turned out to be Austin’s peccadillo, which resulted in widespread agricultural devastation. We all now know that the rabbit found the southern Australian environment to its delight and proceeded to repay the kindly benefactor who brought it to this Shangrila by multiplying at a biblical rate. It became Public Enemy No. 1, up there with Al Capone. The nation rallied against this intruder. For the many decades that followed, systematic shooting, poisoning, ferreting and ripping up and filling in of home burrows were methods encouraged and followed diligently by harassed and frustrated landholders.
Undoubtedly imbued with tough new Aussie traits, tempered by an inherent British fighting spirit, the bunny took all this on its furry little chin. It continued to thrive and to breed prolifically across most of the southern continent, including Tasmania, where another well-meaning unidentified early settler introduced a few breeding pairs in the 1800s. The Apple Isle also found favour with the bunny, which raised huge litters every few months.
Myxomatosis and calicivirus
Then, the rabbit’s seemingly idyllic existence was interrupted in 1950 by an affliction akin to London’s Black Plague of the 17th century. It came in the form of an extremely virulent disease called myxomatosis, a virus which originated in laboratory rabbits in Uruguay in the late 19th century. Scientists judged it as an answer to our rabbit problem. It soon became known colloquially simply as ‘myxo’ or ‘myxy’.
Myxo is spread by fleas and mosquitoes. It is a terrible disease, which attacks the rabbit’s immune system, causing ugly tumours, blindness and eventual death. Its effect on our rabbits was catastrophic. Statistics compiled at the time estimate that Australia’s rabbit population was reduced from 600 million to 100 million in just two years.
Despite scientifically-backed guarantees that myxo was unique in targeting only the English/European rabbit, there was trepidation among some sections of the farming community that stock – and even humans – may be at risk. While there is no evidence of this ever happening, pet rabbits were not spared and many succumbed to the disease before a vaccination became available.
But our rabbit in the wild again showed its fortitude by shrugging off the wrath of myxo. Immunity to the disease developed among a percentage of its population. Those who survived appeared to pass on an immune gene to their progeny and numbers again rose alarmingly in many areas in southern parts of the continent.
There is no doubt that myxo continued to claim victims. It still does, particularly during seasons when mosquitoes are in abundance to spread the virus. And over the decades, shooters and ferreters have done their best to help out landholders with a rabbit problem. However, it soon became obvious that more weaponry was needed if the rabbit was not to again replicate its pre-myxo numbers. Enter calicivirus.
In theatrical terms, calicivirus had a great opening night, but soon failed to impress its critical target audience. There was a surge in the attendance rate, then a falling off in patronage. The script obviously needed some fine tuning. As mentioned, and following on with the theatrical analogy, the directors of RHDV-K5 – the edited version – believe this one is set to lay ’em in the aisles. Officially documented, RHDV-K5 virus is a haemorrhagic disease. It causes internal bleeding, rapid multiple organ failure and death within six to 12 hours of infection.
Looking ahead
Many landholders whose holdings still are afflicted by an overpopulation of rabbits applaud news of this new biological killer agent. They have voiced their accolades on public and popular media. But the adage that you can’t please all the people all the time holds up again. There are always those who view any new technology, particularly of a biological nature, with a jaundiced eye. Their concerns mirror those of pet lovers and licensed rabbit farmers throughout Australia (in states where such activity is legal, but that excludes Queensland, where even possession of live rabbits is still against the law) who also are vocal in their concerns.
The Australian National Rabbit Council is positively terrified as to what RHDV-K5 could do to its industry, without the guarantee of an effective vaccine against the virus. In fact, its members are lobbying the Federal Government in an effort to either delay release until more research is done, or an effective vaccine can be proved and provided. The organisation has a number of petitions online to help with its lobbying.
Hunters and those of us who enjoy a good feed of delicious wild rabbit are ambivalent in our response. On the one hand, we can understand the need for control of the rabbit population as there is little doubt that numbers are on the increase in some areas.
However, the thought of total eradication of the species is abhorrent to some. After all, the humble bunny has become part of the Australian landscape, as well as an accepted culinary delicacy. Wild rabbits, when available from specialty butchers can set you back $25 or more each. Kilo for kilo, this is far more expensive than chicken!
Many are puzzled why there is not more focus on rabbit farming as a viable option for properties in areas where the animals obviously thrive. During periodic droughts, the price of a rabbit carcass would exceed many times that of a stricken sheep. A rabbit is known to live a healthy and fruitful life, while ewes and their lambs are dying of hunger all around it.
Meanwhile, a codicil to the good news – or bad news, depending which side of the rabbit debate you are on – is that, officially, the expected kill rate by RHDV-K5 is only about 40 per cent. That’s according to the bloke at the head of it all, chief executive of the Invasive Animals Cooperative Research Centre (CRC) Dr Andreas Glanznig. Dr Glanznig is reported as saying that because of the predicted low kill rate, his CRC and other rabbit researchers are already looking for even more effective biological control agents. And so the battle rages on.