Cane toads, the green and warty invasive animals that are spreading ruin throughout ecosystems in northern Australia, may not continue their relentless march southward towards the sea. According to a new study, lower temperatures in the south may stop the toads in their tracks. Researchers coaxed the toads into hopping through a 2-meter course in a laboratory to make a so-called "cane toad Olympics," and measured the cold-blooded creatures' hops at different temperatures. They found that in temperatures above 80 degrees Fahrenheit, the toads could hop at a speed of over one mile per hour. But below 60 degrees Fahrenheit, they slowed to a glacial .2 miles per hour.
"This means that there's no way the toads could invade southern parts like Melbourne, Adelaide … because they wouldn't be able to move," said researcher Dr Michael Kearney.... The winters of southern Australia would be too cold for the cane toads to forage or spawn, he said [The Age].
Originally introduced to north-eastern Australia as pest control agents, these warty and poisonous amphibians are explosive breeders. They have now overstayed their welcome as they pose a threat to the country's native wildlife [BBC News].
Even since the poisonous toads were introduced to the continent in the 1930s, they have played havoc with the ecosystem both by competing with native species for food, and by poisoning snakes, lizards, and birds that try to feed on them. The new study, published in the journal Ecography, will allow residents of the Australian cities Melbourne and Adelaide to relax for now, but researchers do note that the future is uncertain:
The toads’ only hope is global warming, which could allow them to move [60 miles] farther south than their present limit by 2050 [The Times].
Image: flickr/Stephen Barnett
