Canadian bats being decimated by fungal disease, study says


[The New Brunswick Museum is testing frozen brown bats as part of ongoing white-nose syndrome research/CBC]

Bat populations across North America are being decimated by a fungal disease that is among one of the worst wildlife outbreaks ever recorded.

White-nose syndrome (WNS) is believed to be the culprit. It is caused by the fungus Pseudogymnoascus destructans, which grows on the skin of bats while they hibernate in winter.

An estimated 5.7 to 6.7 million bats have died since the disease surfaced in New York State nearly a decade ago. The disease has since spread to 26 U.S. states and five Canadian provinces.

In New Brunswick, for example, the little brown, northern myotis and tri-coloured bats are nearly extirpated.

Only recently, however, have scientists begun to unlock some clues about why North American bats have been perishing in such large quantities.

A team of international scientists, led by David Hayman, a researcher at Massey University in Palmerston North, New Zealand, found that bats are more likely to die when in more humid hibernation sites. They also found that some species of bats are more susceptible to dying from the fungus, depending on their body size and metabolic rate.

Bats survive through winter hibernation because of energy reserves they have stored up. One common belief about the syndrome is that the fungus causes infected bats to “wake up” frequently from hibernation, depleting their energy stores.

The scientists, however, found bats more likely to survive if they are larger in body size and hibernating in drier, colder sites.

These findings paint a bleak picture for the Myotis lucifugus, or the little brown bat, which has been particularly hard hit in North America.

“By knowing which species might be affected wildlife managers and policy makers can begin to think about what they will have to do in the future if the infection arrives,” Hayman says.

“Our work […] suggests that bat communities will remain in many parts of North America, but the species composition will be very different. And I think this is useful.”

The study involved researchers from Massey University, the University of Florida in Gainesville, the NIH/Fogarty International Center in Bethesda, Md., the U.S. Geological Survey and Colorado State University is published in the latest journal of Science Advances, published by the American Association for the Advancement of Science.

Karen Vanderwolf, a research associate at the New Brunswick Museum and a bat conservation specialist for the Canadian Wildlife Federation, says white-nose syndrome continues its deadly spread in North America.

“In Canada, WNS has almost reached the Manitoba border. Hopefully Manitoba will remain WNS-free this coming winter,” she tells Yahoo Canada News.

But the spread is expected to continue “for the foreseeable future,” she adds.

“There is no known cure that can be widely applied in the field. The fact that hibernating bats are still found in areas of North America where WNS has been present the longest, such as New York, offers hope that a small segment of the population has natural resistance to the disease,” Vanderwolf says.

Research into vaccinations and biocontrols for the syndrome are ongoing an a number of labs, she says.

With the urging of scientists, three species of bat - the little brown myotis, the Northern myotis and the tri-coloured bat - were listed as endangered under the federal Species At Risk Act a year ago.