Rabbits are one of Australia’s most destructive invasive species, causing hundreds of millions of dollars in agricultural losses, driving native animals toward extinction, and degrading landscapes across the continent. What started with just 13 animals released in 1859 has grown into a population estimated at over 200 million, and more than 160 years of control efforts have failed to eliminate them.
How 13 Rabbits Became 200 Million
On Christmas Day 1859, Thomas Austin, a wealthy settler in Victoria, released 13 European wild rabbits on his estate at Barwon Park so he could hunt them for sport. A relative in England had collected and shipped them specifically for this purpose. Australia had no natural predators capable of controlling rabbit populations, and the mild winters and vast grasslands provided near-perfect breeding conditions. Rabbits can produce multiple litters per year, with each litter containing four to eight kits, so the population exploded at a rate no one anticipated.
Within decades, rabbits had spread across most of the continent. By the early 1900s they were already reaching Western Australia. Today, the Invasive Species Council estimates that wild rabbits number more than 200 million, and conservationists warn that favorable seasonal conditions could push that figure even higher.
Damage to Agriculture
Rabbits compete directly with livestock for pasture. In Australia’s temperate grazing regions alone, the cost to wool producers ranges from roughly 7 million to 39 million Australian dollars per year, depending on rabbit density. At the high end, with about 10 rabbits per hectare, the lost wool production more than quadruples compared to areas with lighter infestations. Those figures cover just one segment of one industry. When you factor in crop damage, fencing costs, and control programs across all of Australian agriculture, the total economic impact runs far higher.
The grazing pressure is relentless. Rabbits eat grasses, herbs, seedlings, and crops down to the roots, and they feed at dawn and dusk when competition with livestock is highest. In drought years, when pasture is already scarce, even moderate rabbit numbers can strip land bare and leave nothing for sheep or cattle.
Threats to Native Wildlife
Australia’s native animals evolved without competition from a grazing mammal as efficient as the European rabbit. Several threatened species now struggle to find enough food because rabbits eat the same plants they depend on. Yellow-footed rock-wallabies, brush-tailed rock-wallabies, and southern hairy-nosed wombats all overlap significantly in diet with rabbits and have declined as a result.
The damage extends beyond direct food competition. Ground-nesting birds like the plains wanderer and the malleefowl suffer because rabbits alter and reduce the vegetation these birds need for cover and nesting habitat. When rabbits strip an area of low shrubs and grasses, ground-nesting species lose the protective structure that hides them from predators. The New South Wales government formally lists competition and grazing by feral rabbits as a key threatening process under its biodiversity laws.
Soil Erosion and Land Degradation
Rabbit warrens physically reshape the landscape. Research in semi-arid Australian woodland found that the raised mounds created by warren digging supported an average of just 6 plant species, compared to 14 on undisturbed ground nearby. Warren surfaces were dominated by bare soil and gravel, while surrounding areas were covered by cryptogams (the biological soil crusts that hold arid ground together and prevent erosion).
The soil around warrens is measurably less stable. Tests of both dry and water-stable soil aggregation showed that warren surfaces erode far more easily than adjacent undisturbed land. In a landscape already prone to wind and water erosion, millions of warrens across the continent act like open wounds, accelerating topsoil loss and reducing the land’s capacity to recover. Researchers concluded that even after rabbits are removed, the warrens themselves need to be physically destroyed before the soil can restabilize.
Why Fences Didn’t Work
Australia’s most ambitious physical barrier was the rabbit-proof fence system in Western Australia. Fence No. 1, completed in the early 1900s, stretched 1,833 kilometers and was the longest unbroken fence in the world at the time. Two additional fences brought the total to 3,256 kilometers. It was a massive engineering effort, and it failed almost immediately. By 1902, rabbits had already breached the first fence before construction was even finished. Fence No. 2 had more success keeping rabbits out of farmland for a time, but it too was eventually breached. Physical barriers alone simply couldn’t contain an animal that breeds quickly, digs under obstacles, and exploits any gap.
Biological Control: Initial Success, Then Resistance
In 1950, Australian authorities introduced myxomatosis, a virus originating in South American rabbits, as a biological weapon against the population. Spread by mosquitoes, the virus reduced rabbit numbers by over 90 percent in its first wave, providing enormous relief to farmers and ecosystems. But the reprieve was temporary.
Within just two years, the virus began producing less lethal variants, and rabbits simultaneously started evolving genetic resistance. Resistance rose rapidly in the first decade, then plateaued for 10 to 15 years. A second sharp rise in resistance occurred after 1975, when European rabbit fleas were introduced as additional virus carriers. The fleas were supposed to boost transmission, but the increased exposure also accelerated natural selection for resistant rabbits. By the late 20th century, myxomatosis alone was no longer enough.
The Ongoing Battle With New Viruses
In 1996, a second biological control agent was released: rabbit haemorrhagic disease virus (RHDV1), a calicivirus that causes rapid organ failure in rabbits. It provided another significant population knockdown, but the same evolutionary pattern repeated. Over time, its effectiveness declined as rabbit populations developed partial resistance and environmental conditions limited the virus’s spread in certain regions.
To boost control, state and territory governments released RHDV1a, a naturally occurring variant, across Australia in March 2017. Meanwhile, a newer strain called RHDV2, first reported in Europe in 2010, was detected in Australia in 2015 and is now the dominant strain causing deaths in domestic rabbits. Three types of the virus currently circulate in Australia: RHDV1, RHDV1a, and RHDV2.
The core problem is that each new biological control agent follows the same trajectory. It works powerfully at first, then loses effectiveness as the rabbit population adapts. Conservationists have warned that without new control tools in development, Australia could face another rabbit plague if several years of good rainfall coincide with declining virus effectiveness. The rabbit problem in Australia isn’t a historical curiosity. It’s an active, evolving crisis with no permanent solution in sight.