The cane toad has found its ideal niche in Australia, with the invasive species set to continue its onward march further into New South Wales and Western Australia, scientists have warned.



A new report, led by the University of Melbourne, looked at how cane toads fitted into “niche theory”, which dictates how suited an animal species is to an area based on its environment and interaction with other species.

Researchers found that cane toads filled a wide fundamental niche in Australia, as opposed to the narrow, tightly defined role they have in their native South America.

This means that the toads, which have been blamed for the destruction of native wildlife as they spread across northern Australia, have been able to “colonise” the landscape, largely owing to the lack of natural predators.

In South America, cane toads co-evolved with other toads, while other species developed that prey upon the animals, but these restraints are not in place in Australia.

“Australia has been good to the toads climatically and also in terms of a lack of predators,” Reid Tingley, lead researcher at the University of Melbourne told Guardian Australia.

“In South America, there will be other animals similar to a quoll which would have preyed upon the toads for millions of years. But without that evolutionary history here, Australian animals think it is a native toad, attack it and die.”

Cane toads were introduced to Queensland in the 1930s as a way of controlling crop pests but instead gorged themselves on other local wildlife and spread across northern Australia to Western Australia.

The species, which reproduces in huge numbers, has been blamed for the deaths of native animals such as snakes and quolls. As these animals attempt to eat the toads, toxins within the supposed prey poison and kill the predators.

Tingley said the toads would continue their march across WA while a group that has become established near Sydney airport will eventually link up with toads pushing south into NSW.

A separate report into the spread of tropical areas released on Monday predicts that cane toads, as well as creatures such as crocodiles, will become more populous in southern parts of Australia owing to climate change. The tropics are expected to expand by about 200km every 25 years because of rising temperatures.

“Any sort of increase in tropical area will be a good thing for toads,” Tingley said. “If there are future increases in temperature, that will increase their range south, but there will be other considerations too. For example, toads depend upon precipitation and it generally only rains in Perth when it is cold.”

Researchers are working on a way to stop the spread of toads in WA. While the toads are likely to surge across the Kimberley, it’s hoped they may be stopped when they reach Broome.

“It’s likely they will hit Broome in the next 10 years or so,” Tingley said. “They will be met with a very narrow strip of suitable habitat, due to the fact they need water all year round. Toads have little chance of survival if they go 10 days or so without sitting in water.

“The idea is that if we work with pastoralists, rangers and environmental groups, we could restrict the toads’ access to bodies of water, thereby stopping their spread. We could remove water spots in favour of tanks of water that don’t leak, essentially creating a waterless ‘firebreak’ to stop their spread.”