Some bats facing the grim threat of White-nose Syndrome (WNS) may find an unusual refuge in Maine this winter: an old military bunker that housed nuclear weapons during the Cold War. One of 43 bunkers on the Aroostook National Wildlife Refuge is being refurbished as a potentially safer hibernation site for bats, the Portland Press Herald reports.
|This old Cold War-era military bunker was refurbished into a home for bats. Photo courtesy of U.S. Fish & Wildlife Service/Steve Agius
Actually, the U.S. Fish and Wildlife Service is turning two abandoned bunkers into artificial caves. The newspaper says one bunker was refurbished to meet the bats’ needs and then sterilized in hopes of eliminating the P. destructans fungus (formerly called Geomyces destructans) that causes WNS. The other will be left unchanged to serve as a control to determine the impact of the test bunker’s “manipulated environment,” assistant refuge manager Steve Agius told the Press Herald.
White-nose Syndrome has spread across eastern North America, killing more than 6 million bats since it was discovered in a New York cave in February 2006. The Aroostook Refuge experiment is aimed especially at little brown myotis. Once among the most common American bats, the species now faces the likelihood of regional extinctions because of WNS. The refuge was created in 1998 on part of the former Loring Air Force Base.
WNS is killing bats of seven species in 23 U.S. states and 5 Canadian provinces. It’s named for the cold-loving white fungus that’s typically found on the faces and wings of infected bats. The wildlife disease causes bats to awaken during hibernation and use up the stored fat reserves that are needed to get them through the winter. Mortality rates approaching 100 percent are reported at some sites.
The bunker project “is like the Noah’s Ark strategy,” Agius told reporter North Cairn. The impact of WNS is so severe, he said, that we must protect these animals or they could disappear completely.
A major goal is to provide usable hibernation sites that can be decontaminated each year before bats return for their winter hibernation. Fungicides or other toxins can kill the P. destructans fungus, but they would also destroy the complex ecosystems that thrive within natural caves, especially those used by bats.
The first bunker already has been retrofitted with temperature and humidity controls, insulated doors, a thermal blanket and a layer of soil over its rounded top, Cairn wrote. The next step is a thorough cleaning to remove the fungus.
In hopes of attracting bats to the bunkers this fall, as hibernation season approaches, the team plans to broadcast recordings of bats’ swarming calls. Hibernating bats typically gather by the hundreds or even thousands at “swarming sites,” which are usually near hibernation caves.
If all goes according to plan, Agius told the newspaper, some little brown myotis might flock to the artificial cave and perhaps avoid, or at least reduce, exposure to the fungus.
Scientists have confirmed that the WNS pathogen is “essentially an invasive fungus from Europe,” Scott Darling, a Vermont state biologist who’s participating in the experiment, told the newspaper. Although the fungus is found in Europe, the disease itself is not, which suggests European bats may have developed resistance. The Press Herald reported that biologists theorize that if U.S. bats can survive their exposure to the fungus, they “might possibly adapt and evolve resistance, too.”
The artificial-cave project began earlier this year, when 30 male bats, all infected with WNS, were brought from Vermont and New York, Agius told the newspaper. They were placed in the sealed bunker to see if they would accept the artificial cave, in which a pool of water and some roosting structures were added. Temperature and humidity were kept close to the conditions found in natural hibernation caves, the Press Herald said, and the bats were monitored through the winter.
The bats seemed to accept the artificial cave, although a number of them died of WNS. Now the real test begins this winter.
“It's really a race against time,” Darling said. “We make these bold steps and we learn something.”