Racing cane toads reveals they get cold feet on Southern Australi...(aid Dr. Tracy. Their range would also b...)

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 couldn't 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.

"These are perfect conditions for growing wine, but you are unlikely to meet a toad at a winery" said Dr Kearney. In many of these places the air temperature at night the active period for toads - is often above 15 degrees Celsius, but this only happens during summer, and evaporation in the dry summer air cools them down too much.

"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". Dr. Kearney said.

"In one way it is obvious why dry conditions are bad for frogs they lose too much water" explained Dr. Kearney. "But having wet skin also provides frogs with a thermal challenge because the evaporating water takes heat away from their bodies and often makes them colder than the air."

They found that a moderate global warming could allow toads to move 100 km further south than their present limit by 2050. This would make conditions in Sydney slightly better for toads, and the only other city at risk of toad invasion
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