Across Australia’s vast landscapes, the balance between nature and agriculture has long been shaped by quiet battles—some visible in fields and forests, others unfolding in laboratories and research stations. Among the most enduring of these struggles is the story of the European rabbit, a small animal whose presence has left an outsized mark on the continent’s ecosystems.
For more than a century, rabbits have moved across Australian farmland and bushland with remarkable persistence. Introduced in the 19th century, they multiplied rapidly in an environment where natural predators were limited and conditions often favored their survival. The result was a transformation of landscapes, with grazing pressure stripping vegetation and challenging both farmers and conservationists.
For decades, biological control methods have been central to managing rabbit populations. Two of the most well-known tools—myxomatosis and rabbit hemorrhagic disease virus, commonly known as calicivirus—once dramatically reduced rabbit numbers across the country. Their introduction marked some of the most ambitious biocontrol experiments ever undertaken in wildlife management.
When myxomatosis was first released in the 1950s, its impact was swift and dramatic. Rabbit populations that had seemed unstoppable suddenly collapsed across large parts of Australia. Farmers reported immediate relief as pasturelands began to recover from years of heavy grazing.
Yet nature rarely stands still. Over time, rabbit populations began to recover as the animals developed genetic resistance to the virus, while the virus itself evolved into less lethal forms. What had once been a powerful biological weapon gradually became less effective in maintaining long-term population control.
A similar story unfolded decades later with the introduction of calicivirus in the 1990s. Known scientifically as rabbit hemorrhagic disease virus, it once again drove sharp declines in rabbit numbers, particularly in arid regions where environmental conditions favored the spread of the disease.
But like myxomatosis before it, calicivirus has gradually lost some of its early effectiveness. Researchers say that rabbits in some areas are again developing partial resistance, while environmental factors can influence how well the virus spreads.
In recent years, land managers and scientists have reported that rabbit populations are once again rising in several parts of Australia. The increase has renewed attention on how biological control tools function over time and how they might evolve to remain effective.
Researchers continue studying improved variants of existing viruses as well as new strategies for managing rabbit populations. Some experimental programs focus on updated strains of rabbit hemorrhagic disease that may overcome resistance in certain populations.
At the same time, experts emphasize that biological control rarely works in isolation. Effective rabbit management typically combines multiple approaches, including fencing, habitat management, baiting programs, and coordinated regional efforts among landholders.
For farmers and conservationists alike, the challenge is not only reducing rabbit numbers but also protecting fragile ecosystems where native plants and animals can be affected by intense grazing.
Australia’s experience with rabbit biocontrol has often been studied internationally as one of the most ambitious and complex examples of ecological management. It illustrates both the promise and the limitations of biological solutions in controlling invasive species.
As scientists continue exploring the next generation of control measures, the broader lesson remains clear: ecosystems are constantly adapting, and the tools used to manage them must evolve as well.
For now, myxomatosis and calicivirus remain part of Australia’s ongoing strategy to manage rabbits, even as researchers and land managers search for new ways to address the growing populations appearing across parts of the country.
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Source Check (Credible Media Identified) ABC News Australia The Guardian Australia The Conversation Australian Broadcasting Corporation Rural The Sydney Morning Herald