Cane toads restrained

23 February 2011

Scientists in Australia have discovered a simple way to stop deadly invasive cane toads from spreading any further into Australia’s arid regions.  The research, published today in Proceedings of the Royal Society B, reveals that by fencing off man-made water points (used in agriculture and livestock rearing), toads can be effectively controlled and their relentless spread curtailed.

The introduction in 1935 of the cane toad B. marinus to Australia was an ecological disaster, with the poisonous toad today spreading over almost one million kilometres of Australian land and poisoning the majority of native predators unfortunate enough to eat it.  Surprisingly, the invasive creature is not well adapted to hot and dry conditions, but nonetheless in recent years it has started to take over seasonally arid areas of Australia in the Northern Territory.  The scientists tested whether man-made water boreholes in this area might be acting as ‘invasion hubs’ for the toad, providing a haven for them in the driest weather and allowing them to colonise even more land in these areas.

By fencing off boreholes so that toads couldn’t access them and then removing by hand any toads that found themselves inside the fencing, the researchers achieved a drastic reduction in the local cane toad population.  They monitored toads that were removed from the boreholes and discovered that the majority of them went on to die of dehydration, suggesting that the water points are vital for the toads’ survival in these regions, so removing toads’ access to them could be a simple and inexpensive way to control their further spread into these areas.  Furthermore, the scientists found that the fences appeared to have no detrimental effect on native animals, being easily surmountable by birds, pythons, kangaroos and other local wildlife.

The authors point out that this method is not a “silver bullet” for cane toad control, but remind readers that “most research on cane toads has focused on identifying and developing biological control agents; all have been unsuccessful to date.”  While this new method may not represent the ultimate solution for Australia’s toad problem, controlling the further spread of these devastating agents of biological destruction should be a positive first step in limiting any further damage caused by them.

Image credit: Michael Linnenbach