A 19th century farmer may be to blame for Australia’s rabbit scourge

On Christmas Day 1859, a shipment of 24 rabbits arrived in Melbourne, Australia, from England. The bunnies were a gift for Thomas Austin, a wealthy English settler who aimed to establish a colony of the creatures on his Australian estate. He accomplished that—and then some.

Just 3 years later, thousands of his European rabbits (Oryctolagus cuniculus) were hopping about. By 1865, Austin would boast to the local paper of killing some 20,000 bunnies on his property, where he hosted rabbit hunting parties for English royalty such as Queen Victoria’s son, Prince Alfred.

Austin was not the first person to bring rabbits Down Under. Five of the animals were aboard the first fleet of British ships to reach Sydney in 1788, the beginning of roughly 90 rabbit introductions along Australia’s eastern coast over the next 70 years. Yet Austin’s bunnies were the ones that came to dominate the continent, a new study finds. About 200 million rabbits now wreak havoc on crops and native plants, causing $200 million a year in agricultural damage. And nearly all of them, researchers conclude, can be traced back to the fateful shipment Austin received in 1859.

To unravel how the rabbit plague began, Francis Jiggins, a geneticist at the University of Cambridge, and his colleagues analyzed the genetics of 187 rabbit specimens collected across Australia. They also tested potential source populations in England and France and a handful of rabbits from Tasmania and New Zealand, places that experienced their own devastating rabbit invasions.

Most of Australia’s rabbits, aside from two localized contingents around Sydney, shared a common ancestry, the team reports today in the Proceedings of the National Academy of Sciences. The rabbits’ genomes also revealed the invasion’s epicenter was near the site of Austin’s estate in Victoria. As the bunnies spread farther away from the site, the population became less genetically diverse, resulting in a homogeneous horde of rabbits. What’s more, the researchers pinpointed several genetic similarities between Australian rabbits and bunnies in southwestern England, where Austin’s family collected the first batch of rabbits to ship to Australia. The researchers conclude that Australia’s ongoing rabbit scourge began when Austin let the initial shipment of 24 rabbits loose on his estate.

The genetics gave clues to why this population was primed for invasion. Accounts of earlier Australian rabbits mention floppy ears and fancy colored fur, two traits common in domesticated rabbits, suggesting they may have been too tame to adapt to Australia’s wild landscape. But Australian rabbits descended from Austin’s brood had a large amount of wild ancestry, the genetic analysis revealed.

The historical record backs this up. Austin family letters and lore reveal Austin’s brother sent several wild-caught rabbits in addition to domesticated bunnies to Australia. The rabbits began interbreeding during the 80-day boat journey.

Austin’s rabbits had another advantage over their predecessors: They arrived to a more forgiving Australian environment. When earlier rabbit newcomers ventured out into the bush, they encountered strange plants and a slew of carnivorous reptiles, marsupials, and dingoes. But by the mid–19th century, the outback was being transformed into pasture, and predators were being hunted to protect livestock. “It was like a perfect storm,” says co-author Joel Alves, an evolutionary geneticist at the University of Oxford.

Australia’s landscape is still struggling with the fallout from this storm. Once the rabbits hopped outside of Austin’s estate, they spread by more than 100 kilometers per year despite fences and strains of smallpoxlike viruses engineered to wipe them out. In just 50 years, the animals had colonized an area roughly 13 times larger than their native European range, a rate faster than any other introduced mammal, including pigs and cats.

And they keep breeding. “It’s like a faulty brake on a car,” Alves says.

Still, not all scientists blame Austin alone for Australia’s rabbit plague. David Peacock, an ecologist at the University of Adelaide, says other rabbits were released on the continent around the same time as Austin’s. In 2018, Peacock co-authored a study positing that the rabbit invasion was sparked by multiple rabbit introductions.

But he applauds efforts to untangle the origin of Australia’s rabbits, saying they could aid efforts to create more targeted pathogens to control and potentially eradicate rabbit populations. “The better [we understand] the origin, spread, and genetics, the better we can manage Australia’s most serious pests.”