Australasian Science: Australia's authority on science since 1938

Cane Toad Invasion Front Is Accelerating in Straight Lines

Cane toads at the front of an invasion travel in straighter lines than established populations, helping to explain how they are increasing their range in Australia at a rate of 55 km/year – a fivefold increase since the species was introduced in 1935.

The discovery, published in Proceedings of the Royal Society B by Prof Rick Shine of the University of Sydney, builds on research he published last year which found that cane toads at the vanguard of invasions have longer legs that enable them to move twice as quickly as toads behind the invasion front (AS, Oct 2013, p.12).

“Taking a straight trajectory can massively increase the distance you travel per day, so the evolution of straighter paths might be a particularly effective way to achieve rapid dispersal,” said co-author Dr Gregory Brown.

The research studied the movements of cane toads in the Adelaide River, Northern Territory, since 2005 when cane toads first arrived in that area. Vanguard toads were monitored with transmitters during the wet season, when they travel the greatest distances.

Not only did the invasion-front toads move further and along straighter paths than toads arriving later, but the offspring of invasion-front toads inherited their parents’ behaviour. “We can conclude from this that the trait of travelling in a straight line can be inherited,” Shine said.

“These findings are worrying. They confirm that invasive animals can evolve quickly to move faster, which makes it even more difficult to manage the threat they pose to our native wildlife.”