PARIS: Scorching heatwaves linked to climate change have caused thousands of Australian bats to drop dead after flapping their wings in a desperate bid to cool off, scientists say.

On one day alone in 2002, up to six per cent of the flying foxes in nine colonies in New South Wales, southeast Australia, died when temperatures hit 42°C, according to the study. Most alarming, said the biologists, was the mortality rate among young bats, which was as high as 50 per cent.

"The effects of temperature extremes on flying foxes highlight complex implications of climate change for behaviour, demography and species survival," says the study, which is published today by the Royal Society, Britain's de-facto academy of sciences.

The fruit-eating, winged mammals play a critical role in local ecosystems, helping to pollinate wild and cultivated crops and disperse seeds, the researchers point out.