Cane toads wouldnt be able to survive in Southern Australia due to cold temps

August 27th, 2008 - 2:04 pm ICT by ANI  

Washington, August 27 (ANI): A new research has suggested that the cane toad would be unable to survive in Southern Australia because its march will grind to a halt once it is physically too cold for the animal to hop.

The research was carried out by Dr Michael Kearney, from the Department of Zoology at the University of Melbourne, and collaborators from Australia and the USA.

The cane toads cannot survive in much of Southern Australia because they would be too cold to move about and forage or spawn, said Dr Kearney.

Their study is unique in that it is based on an understanding of the capabilities of the toad itself whereas many other studies some predicting that Melbourne would be invaded by the toads are based on correlations between climate and the places the toads are living at now, which can lead to errors.

Since their introduction to Australia in the 1930s, cane toads have been steadily advancing across Australia and have already invaded Brisbane and Darwin.

Once used as pest control, the toads are now a devastating pest themselves; so an accurate prediction of their final range and rate of movement is essential.

For the research, Dr Kearney and his colleagues, including Dr. Ben Phillips from the University of Sydney and Dr. Chris Tracy from Charles Darwin University, set up a 2 m sprint event for toads at a range of different temperatures to see what temperatures would slow toads down the most.

The team used field-collected toads from four populations across the invasion front.

We found that cane toads can barely hop once they get below about 15 degrees Celsius, said Dr. Tracy. Their range would also be constrained by the limited availability of water for their tadpoles in some parts of Australia, he added.

After racing their toads, Kearney and his colleagues used sophisticated computer models developed by Dr Warren Porter at the University of Wisconsin, Madison USA, to predict how cold toads would get at different times of the year across Australia.

They found that it is so warm and wet around Darwin that toads there can hop more than 50 kms per year.

However, the cooler, drier conditions around Sydney or Perth mean that toads can barely manage 1 km per year, and they couldnt move at all under typical weather conditions in Adelaide, Melbourne and Hobart.

They found that toads have particular difficulties in parts of southern Australia with what are known as Mediterranean climates places with cold wet winters and warm dry summers.

Our study is particularly helpful in predicting where cane toads could live under climate change because we have identified a cause-and-effect way that climate limits the toads, said Dr. Kearney. (ANI)

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