Australian Rabbit Plague
If ever a monument is erected to honour the law of unintended consequences it ought to feature Thomas Austin of Winchelsea, Australia. A transplanted British farmer, Austin felt nostalgic about his home country. He particularly missed the noble sport of shooting rabbits in the countryside.
In 1859, he imported a couple of dozen wild rabbits from Europe, so he could sit on his porch of an evening and pop off a few. As he put it “The introduction of a few rabbits could do little harm and might provide a touch of home, in addition to a spot of hunting.”
Scarcely has there ever been a greater underestimate of the calamity caused by a simple decision.
Breeding Like Rabbits
It has been observed by many that rabbits go about the business of procreation with considerable gusto. The University of Miami biology department gives us an idea of how fecund these critters are. One female will have an average litter of six babies and in six months these will be ready to breed.
At the end of year two, that single mother’s offspring will, theoretically, number 1,369 females. By the end of year three there are 50,653 females. After seven years, in theory, that single female’s progeny number 95 billion females.
This is just females. There will likely be an equal number of males. This is just a theoretical calculation that does not account for early mortality or other factors effecting reproduction.
In the wild, the average rabbit only lives for a year or two.
Within a couple of years of Mr. Austin’s imported rabbits being on the loose those that escaped the lead from his shotgun had replenished their numbers and then some.
They overran his property and that of his neighbours, an event that, no doubt, affected his popularity in the farming community.
In 1866, more than 14,000 rabbits were shot on Austin’s property alone. According to the Australian Broadcasting Corporation (ABC), “By the 1920s, Australia’s rabbit population had swelled to 10 billion.”
Rabbits are voracious eaters. Virtually any plant is on their menu, leaves, flowers, stems, even bark. Soon, the landscape began to resemble the aftermath of the passing of a swarm of locusts. Having denuded one area of its plant life, the bunnies simply moved on to still lush pastures.
As Bill Bryson notes in his book In a Sunburned Country “By 1880, two million acres of Victoria had been picked clean. Soon, they were pushing into South Australia and New South Wales, advancing over the landscape at a rate of 75 miles per year.”
And, the settlers whose land was ravaged encouraged the rabbits by creating water holes for their sheep and cattle that kept the pests from dying of thirst.
The rabbits devoured the food supply that had sustained native mammals that couldn’t compete with the hordes of rodents. They removed much of the vegetation that held Australia’s thin topsoil together. In the 1890s, the country suffered a decade-long drought and vast quantities of precious soil blew away.
Shooting, trapping, and poisoning barely made a dent in the population, but disease did.
In 1950, a virus common among cottontails in South America was introduced to Australia. It caused an ailment called myxomatosis, that is harmless for humans and other mammals but catastrophic to rabbits.
Myxomatosis, the ABC explains causes “the rabbits [to] develop lesions filled with mucus. The mucus accumulates under the rabbit’s skin, leading to internal swelling. Most rabbits die of haemorrhage and seizures within 10 days.” It’s not pretty but it’s effective.
The mortality rate is 99.9 percent. But the 0.1 percent that were immune passed on their defence against myxomatosis and soon the survivors were – well – breeding like rabbits again.
In 1995, a virus from China called calicivirus was tried. It caused the rabbits to bleed to death. But again, as with myxomatosis, it was only effective for a while and then the rabbit population sprang back.
A 2,023-mile long fence has been erected to keep the bunnies out of uncolonized areas. Donald Trump take note that this has not always been successful; sometimes, the rabbits have already made it into the fenced off region. Others have burrowed under the barrier or jumped over it, or simply scampered through a gate inadvertently left open.
Warrens are fumigated or a stick or two of dynamite is inserted to dramatic effect. Another technique is ripping. Sharp tines are driven into the soil around a warren and then dragged through it by a tractor. The rabbits are either sliced in two by the tines or buried alive in their collapsed warren.
Of course, the loud reports from shotguns and rifles can be heard all over rabbit-infested areas. All to no avail.
Nobody knows for sure how many bunnies live in Australia today, but most estimates hover around the 200 million mark.
Humans seem to have an awful lot of trouble learning from the mistakes others.
Even while suffering the ferocious depredations of rabbits people formed acclimatization societies in Australia. They worked from the notion that Australia’s flora and fauna was dull and boring and needed to be improved by the introduction of new species.
In 1862, the Governor of Victoria, Sir Henry Barkly, decided it would be a capital idea to introduce monkeys to the forests. As he put it they would provide for the “amusement of wayfarers, whom their gambols would delight.”
Sir Henry did not act on his musings before he was called back to Britain. His replacement, Sir Charles Darling, fancied bringing in boa constrictors. Fortunately, that stupid idea failed to get traction in a country that already had 66 of the world’s most venomous snakes.
But, others in the acclimatization business got their pet projects off the ground. Today, 100,000 wild camels wander the western and central deserts. Foxes are a nuisance animal and millions of wild donkeys and horses are on the loose.
Bill Bryson notes that “There are so many introduced species, in fact, that the once-mighty red kangaroo is now only the thirteenth largest animal in the country.”
Theoretically, two mating rabbits can produce 33 million relatives in just three years.
Under the 1883 Rabbit Nuisance Act an Australian child could receive a sentence of six months in prison for releasing a pet rabbit into the wild.
The Tale of Peter Rabbit by Beatrix Potter was first published in 1901. It has since been translated into 36 languages and has sold more than 45 million copies.
A common mating behaviour among rabbits is spraying urine.
According to The Guinness Book of World Records the longest-lived rabbit, called Do, died in 2013 at the age of 17 years and two weeks.
Chairman Mao ordered that every Chinese family had to kill at least one sparrow a week to stop them eating the country’s rice. The project was a failure because sparrows don’t eat rice.
- “In a Sunburned Country.” Bill Bryson, Doubleday, 2000.
- “Thomas Austin and His Rascally Rabbits.” Grant Oster, Hankering for History, January 18, 2014.
- “Why Spay or Neuter my Rabbit? Some Scary Numbers ...” Dana Krempels, Ph.D., University of Miami, undated.
- “Australia’s Battle with the Bunny.” Wendy Zukerman, ABC Science, April 8, 2009.
© 2016 Rupert Taylor