In Australia, there are concerns that the number of rabbits is increasing exponentially, while the main way to limit the advance of the invasive species is no longer working. Experts are sounding the alarm.

“If we do nothing, we will lose unique Australian animals and plants forever,” warns Heidi Kleinert. She is the national rabbit control coordinator at the Center for Invasive Species Solutions, an Australian non-profit organization.

The consequences for the economy are also major. Rabbits cost the agricultural industry more than 150 million euros per year. But according to experts, that amount could rise to 1.2 billion euros per year if the plague is not tackled.

Rabbits have spread across three-quarters of the Australian continent in recent decades. In total there are an estimated 250 million. That number is increasing quickly, because they reproduce very quickly.

They are already fertile when they are three or four months old. The gestation period is about 28 days and a female can become pregnant again immediately after giving birth. “If you have just two rabbits, they multiply so quickly that after 18 months you have 184,” says Kleinert. “We must do everything we can to eradicate them down to the last rabbit.”

The rabbit plague in Australia started more than 150 years ago, when wild rabbits came from Europe were brought by British colonists. The animals were shot as a hobby. Genetic research shows that almost all wild rabbits are descended from the first 24 ancestors released for rabbit hunting by a British landowner.

The rabbit is not the only invasive species causing problems in Australia. Mice, deer, foxes, pigs and cats also cause enormous damage. But rabbits take the cake, says Kleinert. “The rabbit threatens 322 native plants and animals. It is the most harmful invasive animal in Australia.”

The rabbit devours lush Australian grasslands and causes soil erosion with all its burrows. Moreover, a kind of domino effect is created. Rabbits are prey for other invasive animals, such as feral cats and foxes. More rabbits means more of these animals, which in turn threaten native species.

The height of the rabbit plague was in the 1920s. At that time there were an estimated 10 billion rabbits in Australia. For years, people tackled the problem by shooting and poisoning rabbits on a large scale.

However, this had little effect due to the animals’ rapid reproduction. “The national archives contain photos from that time that show the damage. There is no grass at all on the meadows anymore, only dust,” says Kleinert. “Farmers ran away from their land because they could no longer compete with rabbits that ate everything. People were displaced and vegetation was destroyed.”

That’s why scientists started an experiment in 1950: a highly contagious and deadly virus for rabbits was released. The myxomatosis virus spread rapidly among wild rabbits, reducing their population to around 100 million.

It was extremely effective for a long time, but at a certain point the animals became resistant to the virus. A new virus was therefore introduced in the 1990s, and another variant in 2017. But most rabbits have now also become resistant to this virus.

A new virus has not yet been found. That is why scientists are also looking at other, more experimental techniques. For example, research is being done into genetic modification of rabbits, so that the females only produce male offspring or become infertile.

But financing research and other methods to control the rabbit population is a major problem, says Kleinert. The government is systematically spending less money. Some funds have even been stopped completely. “But even if we had a lot of money, we would still need at least ten years to research a new virus, develop it and get permission to spread it among wild rabbits,” says Kleinert.

The cuddly image of the rabbit also causes resistance to the approach. “But if you really love nature and animals, you will ensure that the rabbit population becomes smaller,” says Kleinert. She hopes that the government will learn from the past and provide more money soon, before it is too late. “We need to learn from history and realize that rabbits are thieves of our landscape. If we do nothing, they will continue. They will not just disappear.”