December 2007, Volume 5, Issue 12

Climate Change Threatens Bats

Heat waves blamed on global climate change are killing alarming numbers of flying foxes in Australia, according to a study by British and Australian biologists. Researchers documented the deaths of up to six percent of flying foxes in nine colonies in New South Wales on a single day in 2002, when temperatures hit 107.5 degrees F (42 degrees C), reports Agence France-Presse.
The international news service said the Australian bats died when they could not cool themselves by desperately flapping their wings. The study by the United Kingdom’s Royal Society also cited potentially catastrophic mortality rates as high as 50 percent among young flying foxes.
“The effects of temperature extremes on flying foxes highlight complex implications of climate change for behavior, demography and species survival,” the study said. The fruit-eating bats play a critical role in maintaining healthy ecosystems by helping to pollinate wild and cultivated crops and dispersing seeds, AFP reported.
The news service said the two species most affected by heat waves – the black flying fox (Pteropus alecto) and the gray-headed flying fox (Pteropus poliocephalus) – already are listed as “vulnerable” on the New South Wales Threatened Species Conservation Act of 1995. In addition to being battered by the weather, flying foxes are threatened by human encroachment of their habitat and are often killed because of exaggerated fears of damage to fruit crops.
AFP said the researchers, led by Justin Welbergen of Cambridge University, monitored 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,” the news story said.
“First, the animals sought shade and began ‘wing fanning’ to cool themselves. Within a couple of hours, the flying foxes were panting, and soon they were drooling saliva. Finally, the study found, ‘individuals began falling from the trees ... and died within 10 to 20 minutes.”
The researchers estimate that more than 30,000 flying foxes have died due to 19 similar heat waves since 1994.

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