National Park Service takes unprecedented step in Smoky Mountains to save endangered bats

Vincent Gabrielle | Knoxville

Show Caption Hide Caption See snowy Smoky Mountains in video Take a journey into a snow-covered Smoky Mountain National Park on Dec. 2, 2019.

In the summer of 2019, the near-silence of a secluded, mossy hollow in Great Smoky Mountains National Park was disturbed by the sound of rock drills and hammers.

Half inside a cave, a team of wildlife technicians and trail crew members were moving a pile of debris that blocked the entrance. For eight hours the six-person crew shoveled “a dump truck of rocks” and boulders by hand to clear out a narrow passage to a massive cave.

Ordinarily, the National Park Service would not do something like this. Natural processes, like erosion, are supposed to occur within the parks to maintain their wilderness character.

But in this case, wildlife conservation officials decided to do something unprecedented.

They decided to reopen the cave after it had been sealed for a year.

Reopening the cave is a gambit in an otherwise dire situation. Over a dozen bat species nationwide have been devastated by white nose syndrome, an invasive, infectious fungal disease. Pseudogymnoascus destructans, the cold-loving fungus responsible for the white nose syndrome, infects bats only while they hibernate.

“It’s sort of like a terrible case of athlete’s foot,” said Winifred Frick, chief scientist of Bat Conservation International, “It eats through their skin and causes them to wake up while they’re trying to hibernate.”

The bats, wakened time and again during hibernation, starve to death before spring or die of exposure. Millions of bats have died since the disease was discovered in 2006. The situation has become so dire that scientists are trying to develop treatments for bats in the wild.

“If it hadn’t been at this cave, it probably wouldn’t have been done,” said Ryan Williamson, the wildlife technician who led the cave clearance team. The cave is a hibernation site (or hibernacula) for the endangered Indiana bat, little brown bat and tri-colored bat.

Parks officials have asked Knox News to not identify the cave to avoid drawing curious explorers to a sensitive habitat in America's most-visited national park.

“There are few hibernacula that are actually known — preserving the few we know is pretty crucial for the population” Williamson said.

This approach had never been tried before.

"That sounds like a first to me," said Scott Pruitt, field supervisor of the Indiana Field Office. Pruitt works extensively on bat conservation in Indiana. "I do not know of a (cave) that was completely closed and reopened."

'A lot of people don't appreciate bats ...'

Bill Stiver, the supervisory wildlife biologist for the Smokies, told Knox News that the park’s three types of bat — the Indiana bat, the little brown and the tri-color — have lost 91% to 95% of their populations.

The little brown bat until recently was the most common bat in North America with a population in the millions. It is now listed as endangered by the International Union for Conservation of Nature, Canada and several U.S. states.

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Those declines could disrupt whole ecosystems.

“A lot of people don’t appreciate bats for what they are,” Stiver said.

Bats are crucial for insect population control, pollinating nocturnal flowers and for keeping some cave ecosystems alive. In some caves, bats (and guano) are the only external food source for unseen underground ecosystems.

Parks officials were alerted to the closed cave in the autumn of 2018.

“I’ve been there every fall monitoring bat activity,” said Mallory Tate, a graduate researcher from the University of Tennessee, Knoxville. Tate has been studying bat ecology and behavior at the site for the past three years and was the first to sound the alarm.

“We stopped capturing bats there by September, which is very unusual,” she said.

Autumn is when bats are most active. They spend the last months before winter frantically stocking up on food to survive the long winter. Swarms of bats gather together on fall nights to find mates and socialize. Researchers hypothesize that swarming also helps young bats find safe places to hibernate.

Will the bats return?

For bats to disappear from a safe hibernation site was very unusual. Tate investigated and discovered that a boulder and other debris had washed into the narrow entrance, sealing the bats out.

The bats had lost their winter home.

When circumstances become difficult for animals, National Park Service policy is to let nature take its course. Many national parks, including much of the Great Smoky Mountains National Park, are managed as “wilderness areas” where natural processes are supposed to be free from human control or manipulation.

This case was special.

“The prudent thing to do was restore this critical winter habitat for bats,” Stiver said. Considering the epidemic, conservation officials could not afford inaction. “When there’s a human-caused exotic disease we do have the authority to do something about it."

Even with the urgent need, it still was not clear that this was the correct course of action. Nothing like this had happened before. Nobody was sure the bats would return.

Caves are incredibly sensitive habitats. The closure could have had a permanent impact on the environmental conditions inside, rendering it unfit for bats or other cave dwelling life.

Because of this it took a year of deliberation between federal conservation officials and researchers at the University of Tennessee to come to the decision. “Hopefully if this happens again, it’s not going to take a year to reopen the cave,” Tate said.

The reopening of the cave seems to have had the intended effect. Shortly after the cave was reopened two bat species returned to the cave for autumn swarming.

Whether the other bats will return in future years remains to be seen.

“It’s really promising to see the little browns and tri-colors return just a month after it was reopened,” said Tate, “especially when it’s usually so doom and gloom.”

The return of the bats has the potential to set precedent for conservationists and cave managers nationally and internationally. If the gambit works, cave environments can potentially be restored for threatened species.

Editor's note: Bill Stiver's name was originally misspelled. It has been updated to the correct spelling.