What appeared to be an innocent Christmas present of 24 English rabbits in 1859 would become Australia’s “most devastating biological invasion” according to a new study by the Proceedings of the National Academy of Sciences.
Wild rabbits are not native to Australia and are considered an invasive species. Farmers say the animals are multiplying rapidly and destroying their crops and land, which can lead to massive soil erosion and other environmental problems.
“Biological invasions are a major cause of ecological and economic disruption,” researchers wrote.
“(And) the colonization of Australia by the European rabbit is one of the most iconic and devastating biological invasions in recorded history.”
Using historical records, researchers were able to collect genetic evidence linking this invasion to English rabbits imported in 1859 by a settler named Thomas Austin, tracing the population to Austin’s birthplace in England.
According to historical records, Austin started out with just 24 rabbits on his sprawling Melbourne estate. But within three years, the animals had multiplied into the thousands — and continued to breed, researchers noted.
“Our findings show that despite numerous introductions across Australia, it was a single batch of English rabbits that caused this devastating biological invasion — the effects of which are still being felt today,” said lead author Joel Alves, also a researcher at the University of Oxford.
“That one event caused this massive catastrophe in Australia; the fastest colonization rate for an introduced mammal ever recorded.”
While Austin was not the first person to introduce rabbits to Australia – five of the animals were aboard the First Fleet of British ships that reached Sydney in 1788 and at least 90 imports were made over the next 70 years – they were the descendants of are 24 rabbits that would come to dominate the continent, the study said.
And it concluded that nearly all 200 million wild rabbits in Australia can be traced back to that ill-fated shipment he received in 1859.
“Environmental changes may have made Australia vulnerable to invasions,” researchers said. “But it was the genetic makeup of a small batch of wild rabbits that fueled one of the most iconic biological invasions of all time.”
The researchers also studied how the rabbit population had managed to survive and thrive in Australia’s rugged wilderness.
Genetic analysis revealed that, unlike previous Australian rabbits, which exhibited domesticated traits such as “tameness, floppy ears, and beautiful colored fur,” rabbits descended from Austin’s offspring had a large amount of wild ancestors.
“If animals are bred for domestication, one of the things they lack is anti-predator behavior, (which) is both learned and also evolved,” said study co-author Mike Letnic of the University of New South Wales.
Rabbit infestations have occurred several times in parts of Australia for decades. The continent still struggles with its wild rabbit population today.
The report, the researchers said, demonstrated the importance of maintaining strict biosecurity in Australia.
“These findings are important because biological invasions pose a major threat to global biodiversity, and if you want to prevent them, you need to understand why they succeed,” researchers said.
“The (event) serves as a reminder that the actions of just one person, or a few people, can have a devastating impact on the environment.”