The team reports that in the early 20th century prior to regular firearm use, people would sneak up upon the bats and catch them with nets or thorny branches used to snag wing membranes. Due to the inefficiency of the method, this probably had little impact on population numbers. Flying foxes were so abundant a hundred years ago, that farmers fed them to pigs during hard times.
By extrapolating the density of bat populations in the forests of nearby uninhabited islands to the forested area of Guam a hundred years ago, the team have predicted that island could easily have supported more than 60,000 flying foxes.
However with the arrival of firearms the Chamorro were able to catch the animals in unprecedented numbers. "When disturbed, the bat colonies fly out of the roost [tree] and circle around," said Banack, "[and] hunters could easily shoot hundreds at a time."
The persecution of flying foxes continued throughout the last century and even after the species was listed as endangered by the IUCN and its hunting and trade became prohibited. "Flying foxes are still now frozen and shipped in from other places, and their trade can be very lucrative" despite frequent fines, said Banack.
The researchers document the close correlation between an increase in the consumption of bat from the 1920s and rapidly increasing prevalence of lytico-bodig disease. They also document the decline in the illness, which has gone hand-in-hand with plummeting bat numbers. "The disease is petering out, which is wonderful for the people, but frustrating for the scientists trying to work out exactly what causes it," said Banack.
"It's a very interesting idea" that bat-eating is linked to the illness, comments Michael Heinrich, ethnobotanist at the University of London School of Pharmacy in England. Other studies have also linked plant chemical consumption by indigenous people to diseases, he said. However there needs to be more evidence that bats accumulate toxins in high enough quantities, and that Chamorrans gorge on enough of them to get a nasty dose of neurotoxins, said Heinrich.
Time may be running out for the flying foxes of Guam, however. The last remaining colony of fewer than 200 individuals is found on the grounds of the U.S. Anderson Air Force Base, said Banack. The future doesn't look goodan introduced species of brown snake has been eating baby bats, meaning that virtually none have made it to adulthood since 1982.
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