Ruffner study one of many seeking solutions for fatal bat disease
by Sydney Cromwell
Three species of bats call the iron mines at Ruffner Mountain Nature Preserve home, but they have an unwelcome houseguest.
Pseudogymnoascus destructans, a fungus that grows on cave walls, has been spreading across North America for about 14 years. The fungus is responsible for the fatal White Nose Syndrome (WNS), which has caused a loss of more than 6 million hibernating bats since its discovery.
The disease is especially hard on already endangered species. The rapid and deadly spread has scientists and conservation groups rushing to find a solution before these threatened bat colonies are lost.
The threat of WNS
White Nose Syndrome was first identified in North America in New York in winter 2006, according to Bat Conservation International (BCI) Chief Scientist Dr. Winifred Frick.
Now, it can be found in more than 35 states and seven Canadian provinces, according to whitenosesyndrome.org, a website run by the U.S. Fish and Wildlife Service. The syndrome has also appeared in bats in Europe and Asia, but it appears to be less fatal among those species.
“The fungus likes to be in cold, damp places,” Frick said, which makes bat hibernation spots particularly susceptible to its growth.
The disease is named for the white fuzz that appears on a bat’s nose, ears and wings after contact with the fungus, which is often called “Pd.” The fungus also causes damage to the bats’ skin.
When bats are hibernating within their cave roosts, their bodies must burn stored fat as energy to keep them alive until spring. Bats infected with White Nose Syndrome, however, awaken more frequently from that state of torpor, each time burning valuable energy as their metabolisms become fully active again.
After being woken repeatedly with no chance to replenish their energy stores, many bats with WNS simply don’t have enough stored fat to survive the winter and starve to death. Bats with WNS have also been observed leaving their caves during winter to seek additional food, spending more energy and sometimes dying of exposure to the cold.
In addition to their vital roles within their own ecosystems, many bat species provide unseen pest control from agricultural fields to suburban backyards, eating millions of pounds of insects. The Washington Department of Fish and Wildlife estimates that American farmers would have to spend an additional $3 billion annually in pest control without bats.
“There’s a real sense of urgency to get solutions implemented and deliver them to the bats because bats are dying in such large numbers,” Frick said.
The staff at Ruffner Mountain have been conducting winter bat surveys since 2017 as part of a statewide survey by the Alabama Department of Conservation and Natural Resources.
Ruffner Conservation Director Jamie Nobles said they have found tricolored bats, big brown bats and evening bats living within the preserve’s cave system, as well as Eastern red bats and other tree-dwelling species that are not as affected by WNS.
The bat survey focuses on a single cave system. Nobles said there were 515 bats found there during the 2017 survey, 490 in 2018 and only 340 in the February 2020 survey.
Nobles said they first spotted signs of the Pd fungus in the caves in 2017 and did swabs to verify it was present. They did not see the white fuzz of WNS during this year’s survey and did not do swabs to test more thoroughly, Nobles said, but they believe the fungus is still in the caves.
Ruffner’s bat survey data is too recent at this point to say whether WNS is causing the population decline, or even if that decline is indicative of a larger trend.
“We might have had thousands at one time dwelling in the caves and the mines,” Nobles said.
Still, the signs are enough to cause concern.
Nobles said Ruffner had been interested in learning more about how WNS might be affecting the preserve’s bat populations. After installing a bat gate—which allows bats to travel freely but blocks human access—to the entrance of Mine #3 with the help of the state’s Abandoned Mine Reclamation program, Nobles said the mine became the perfect test site to “take the various treatment methods into the field in a fairly stable environment.”
“We were trying to not only protect these mines for bat hibernacula, but also making this a safer place,” Nobles said.
In November 2018, Ruffner was one of three sites chosen by Frick and her research team for a study on two possible methods of controlling the Pd fungus.
Frick said Ruffner was a good site for the study because it has an existing population of tricolored bats, one of the species that has seen the greatest population declines, and the caves were not accessible to the public. The other two sites were in Arkansas and Winnipeg, Manitoba.
In addition to the trails, nature center and events like the Native Plant Sale that draw the general public to the preserve, Nobles said being a resource for studies like this is part of Ruffner’s mission.
“It’s what Ruffner has been built or established as. We’re definitely not able to conduct this type of research on our own,” he said.
At those three sites, Frick and her research team decided to try out two methods of killing or slowing the growth of Pd fungus on cave walls.
They built “exclosures” to keep bats from roosting in certain areas, then applied either a UV light treatment or a coating of polyethylene glycol to the cave walls in 30 different test spots. Frick said they also applied isopropyl alcohol, which kills the fungus but can’t be used to treat an entire cave, to a section of the walls to compare the effectiveness.
Frick said UV light and polyethylene glycol have both shown some success in killing or limiting the growth of Pd fungus, but this study was an opportunity to see if they were still effective in real world conditions across three different environments.
After the initial application, Nobles served as a de facto field technician for the study in 2019, swabbing the test sites every three months and documenting temperature, humidity and other data to send back to BCI, which is based in California.
This study was funded by a grant from the Bats for the Future Fund, which the National Fish and Wildlife Foundation awards every year to research on White Nose Syndrome.
Frick said some researchers are focusing on possible solutions that involve treating the bats themselves, like vaccines. However, she has focused on ways to control the habitat around the bats instead.
These techniques, if successful, could be done anytime rather than waiting for the bats to return to their roosts, which she believes would make it easier to create “scalable solutions” for local governments, park management or conservation groups to implement.
But changing the cave environment comes with its own set of difficulties, including the challenge of effectively applying a treatment in the twists and tunnels of a cave, or if a product should even be applied in the first place.
“Caves are really sensitive ecosystems, and it’s not going to be appropriate to spray them with something that’s going to kill the natural biota of the caves,” Frick said.
No silver bullet
While the data collection at Ruffner and the other two sites is complete, Frick said a graduate student at the University of Winnipeg who was part of the research team is writing up the results of the study, as part of obtaining her master’s degree.
Until that report is formally published, Frick said she did not want to share details of the study’s data and results. However, she did say that neither the UV light nor the polyethylene glycol treatment was a miracle cure for management of White Nose Syndrome and Pd fungus.
Nobles said the results brought “more questions than answers.”
“It showed that these treatments are effective, but the complexity of caves and mines makes it a little harder to treat an area as well as it needs to be to eradicate or slow the fungal growth,” he said.
That doesn’t mean Frick’s done trying, though.
“I still think that some of the ideas behind an environmental cleaning approach have merit,” she said.
She has already started testing a “fat bat” program in Tennessee, Oklahoma and the Northeast, using UV lights to draw more insects near the entrance of caves where bats roost, creating a “bug buffet.”
The hope is that bats can forage more efficiently “to pack on the pounds, or really grams,” before hibernation, giving them extra energy to survive the effects of WNS through hibernation. Frick said the program has seemed promising in testing so far.
“Bats that put on more fat reserves in the fall have a higher likelihood of surviving the winter even if they’re exposed to Pd,” Frick said.
Frick said there are also many studies across the U.S. trying out other ideas for combating White Nose Syndrome. The North American Bat Monitoring Program is a comprehensive effort by scientists from governmental agencies, academia and private foundations to share data and track trends on the spread of White Nose Syndrome and other threats to bat populations.
“Having worked on this issue for 10 years, I don’t think there’s going to be a silver bullet, but I think there’s a lot of attention and energy around making sure that these bat populations that are still hanging on, how can we give them the best chance of surviving?” Frick said.
What can you do?
Whitenosesyndrome.org provides information on building bat houses
and creating bat-friendly environments in your own backyard.
Avoid entering gated or closed caves or mines. If you do enter a cave,
thoroughly decontaminate your clothes and gear before and after,
to avoid spreading Pseudogymnoascus destructans fungus
through accidental contact on a cave wall.
Frick said the greatest impact an individual can make for bat populations is
to donate to groups researching White Nose Syndrome, like Bat Conservation International,
or to nonprofits focused on overall environmental protection.
“Everyone wants to take an action individually, but sometimes the best action is
to support the organizations that are doing the more specialized work to implement
conservation actions,” she said. “… Bats are dependent on healthy forests and clean water.”