Charles Clover, Telegraph 27 Nov 07;
Scientists say that mass die-offs of Australian flying foxes, among the most dramatic recorded, show how the survival of whole species could be affected by climate change.
On Jan 12 2002, when temperatures exceeded 108ºF (42.9ºC) in New South Wales, 3,500 flying foxes or fruitbats in nine colonies were found dead. Most of these were the tropical black flying fox.
Since 1994 some 30,000 flying foxes have been killed by 19 similar events, with most of these being the temperate grey-headed flying fox, according to Dr Justin Welbergen of Cambridge University.
There was little evidence for die-offs before 1994, the scientists found. Temperatures have risen on average by 0.74ºC on average over the past 100 years.
The higher susceptibility of females and young to higher temperatures can have a serious effect on breeding populations, according to the paper published in the journal, Proceedings of the Royal Society B.
Stefan Klose, co-author of the paper, said: "In a very dramatic way we see the outcome of extreme climate events that are predicted to increase as a result of climate change by the Intergovermental Panel on Climate Change.
"These animals are simply not able to cope with higher temperatures and so they die. They are the seed dispersers for Australia's rainforest so the ecosystem effects could be very considerable."
Climate change makes bats drop dead: study
Yahoo News 28 Nov 07;
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, according to a study published Wednesday.
On one day alone in 2002, up to six percent of the flying foxes in a nine colonies in New South Wales died when temperatures hit 42 degrees Celsius (107.5 degrees Fahrenheit), according to the study.
Most alarming, said the biologists, was the mortality rate among young bats, as high as 50 percent.
"The effects of temperature extremes on flying foxes highlight complex implications of climate change for behaviour, demography and species survival," says the study, published 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.
Besides an increase in extreme weather, flying foxes, are also threatened by human encroachment of their habitat. They are often killed outright as pests.
The two species most affected by heatwaves, Pteropus alecto and Pteropus poliocephalus, are listed as "vulnerable" on the New South Wales Threatened Species Conservation Act, adopted in 1995.
The UN's climate change panel said in an authoritative report on global warming this year that rising average temperatures have already begun to provoke more intense and more frequent heatwaves.
Humans are subject to the effects of such extremes as well: 15,000 deaths were attributed to a month-long hot spell in 2003 in France alone, the panel said.
Exploring the impact of high temperatures on flying foxes, a team of British and Australian researchers led by Justin Welbergen of Cambridge University staked out several mixed-species colonies in Dallis park, in southeast Australia.
On January 12, 2002, in the middle of the Australian summer, the scientists observed how the bats -- hanging from exposed canopy trees -- reacted to the heat.
First the animals sought shade and began "wing fanning" to cool themselves, they reported. Within a couple of hours the flying foxes were panting, and soon they were drooling saliva.
Finally, "individuals began falling from the trees ... and died within 10-20 minutes," the study found.
The researchers estimate that over 30,000 flying foxes have died due to heatwaves since 1994 during 19 similar events.
