Posted on behalf of Amber Dance
Cane toads – big, poisonous hoppers up to a kilogram in weight – have been marching steadily across Australia since they were invited over in 1935, but no-one knows quite how far they could go. Now scientists at the University of Melbourne say south Australians can heave a collective sigh of relief at a toadless life – for the time being.
The toads were inported to eat the beetles plaguing the sugar cane crops; instead they gobbled up everything else, in the process evolving longer legs to expand their territory across the eastern and northern coast of the continent at a rate of 1.8 kilometers a night, and inspired one of the most hilarious science documentaries of all time. The residents of Darwin await their inevitable approach with automobiles and cricket bats at the ready, planning to squish as many as possible.
But the cold may slow them down.
In a study in the current issue of Ecography the Melbourne scientists suggest that some parts of Australia may be too chilly for the cold-blooded amphibians.
Previous theoretical studies compared the climate in the toads’ current range to the rest of Australia, to predict the toads could make a happy home across the continent in Perth and Adelaide. Michael Kearney and colleagues, instead, went straight to the toads to determine their potential range. They raced toads at different temperatures, and found the animals are so sluggish they can barely hop below 15 degrees Celsius. “The toads cannot survive in much of South Australia because they would be too cold to move about and forage or spawn,” Kearney said in a University press release.
The weather should slow the toads in Sydney and Perth, and stop them in their tracks before they reach Adelaide, Melbourne or Hobart. Global warming, however, could allow the toads to progress into Sydney and Perth by 2050.
Of the Australian press only The Age seems to have picked this up at the moment: ‘Melbourne’s cool reception to stop cane toad’.
Image: cane toad by Burning Image / Nam Nguyen via Flickr.