Australia's Rabbit Invasion Began With a Single Settler

It all started with a few rabbits.

On Christmas Day in 1859, a shipment of 24 wild rabbits arrived in Melbourne, Australia. English settler Thomas Austin had requested the animals, hoping to establish a rabbit population on his new Australian estate.

The rabbits (Oryctolagus cuniculus) were caught around a family’s property in Baltonsborough, England, and taken to Austin’s home in Barwon Park, Victoria.

Within three years, there were thousands of rabbits, and by 1865, Austin reported he had killed 20,000 of the animals at his estate.

Although there are stories of other people who also imported the quickly spreading animals to the continent, Austin was likely the original source of Australia’s invasive rabbit plague, according to a new study.

“The rabbit biological invasion of Australia is one of the most iconic invasions in recorded history, with devastating economic and environmental consequences,” lead author Joel Alves, a researcher at the University of Oxford, tells Treehugger.

“Our main motivation was to use genetics to trace the origin of this invasion, see how it matched the historical records, and ultimately figure out what made it so successful.”

Spreading and Thriving

For their study, researchers analyzed the genetics of 187 European rabbits that had been collected in Australia. Tasmania, New Zealand, France, and Britain.

“We used whole-exome sequencing, which in simple terms means we sequenced all the rabbit genes. Then we conducted several genetic analyses of rabbits across Australia,” Alves explains.

They found most of the rabbits were closely related and expanded from Victoria, suggesting there was a single major introduction. They also discovered that Australian rabbits are closely related to rabbits from the southwest of England.

The pattern they found matches the historical record describing the introduction of the wild rabbits in 1859 to Austin’s estate.

“Contrary to the numerous introductions of domestic rabbits that occurred before this, Thomas Austin rabbits were wild and likely better adapted to the wild environment,” Alves says. “We argue that this was the key aspect of their success.”

Earlier reports of rabbits in Australia mentioned traits like floppy ears, tameness, and fancy coat colors. Those are characteristics not usually seen in wild rabbits. But those populations either didn’t thrive or failed to spread outside their original range.

The Austin rabbits, however, didn’t have those qualities and they’re the ones that spread and thrived.

The results were published in the journal Proceedings of the National Academy of Sciences (PNAS).

Disrupting the Ecosystem

Invasive rabbits have made a serious impact on the ecosystem in Australia and can have substantial consequences for biodiversity.

There are currently an estimated 200 million rabbits in Australia, according to Rabbit-Free Australia, a group that works to educate people about feral rabbits and eradicate them.

“They compete with native species for a wide variety of resources, cause overgrazing which prevents the regeneration of native fauna and can cause desertification; their large numbers disrupt ecosystems and trophic cascades,” Alves says.

“Understanding what makes a biological invasion successful is a key aspect of developing mitigating policies that prevent the proliferation of invasive species.”

The study finds that despite many rabbit introductions that were recorded over seven decades in Australia, most of them failed. It was likely because they were domestic and unable to adapt to the landscape.

“All until rabbits with wild ancestry arrived,” Alves says. “Many aspects contribute to species becoming invasive, and our study highlights how genetics can play a major role in this process. It also provides an additional mechanism for why there is often a lag between initial introductions and subsequent invasions.”

Today, Alves says rabbits are “sort of a conservation paradox.”

“In most introduced locations, they are a pest challenging to eradicate,” he says. “Yet, in their native range in the Iberian Peninsula, they are highly endangered despite being a keystone species with a crucial ecological role.”