Disease continues its fatal sweep of bats

The oars splashed, that slight sound magnified as it echoed off rock walls that led to a distant, black point. With each pull, the tunnel’s illuminated opening got smaller – the darkness, greater.

Pete Pattavina paused in mid-paddle. He saw a cluster of creatures. They hung from the wall as the boat floated past. Each was a bat, folded in winter slumber. One day soon, they’d leave their hibernaculum in the mountains of North Georgia.

But how many would venture out of that hole in the ground, the Black Diamond Tunnel? White-nose syndrome, a fungal disease, has killed millions of bats since its discovery about 10 years ago. Despite the best efforts of scientists, the killer has moved ever farther across the nation.

Three years ago, Pattavina, a biologist with the U.S. Fish and Wildlife Service (the Service), for the first time entered the tunnel, a railroad project abandoned with the advent of the Civil War. What he saw in the 1,400-foot shaft left him stunned: an estimated 5,000 Perimyotis subflavus – tri-colored bats – hung from the tunnel’s rocky ribs.

“You should have seen it,” Pattavina said.

A fuzzy brown bat nestled in the crevice of the roof of a cave.

In this 2016 photo, a healthy tri-colored bat hibernates on the wall of the Black Diamond Tunnel. Photo by Pete Pattavina, USFWS.

He’s not seen those numbers since. The population of hibernating bats has steadily declined. In his 2016 visit, he counted 220.

Now, as Pattavina paddled one recent morning, he watched as fellow biologists quietly counted the tiny, snoozing figures. Would their findings be cause for relief or concern?

Insect-disposal machines

The first documented case of white-nose syndrome turned up in the winter of 2006-2007, in a colony of bats hibernating in a New York cave. Scientists noticed the white fungus on the muzzle of the bats and coined a name that has endured. Since then, white-nose syndrome – WNS  – has moved relentlessly across America. It is no respecter of international borders, either: WNS has turned up in eastern Canada, too.

Recent counts in states indicate that time has not slowed the disease. WNS is breathtakingly lethal; in the Northeastern United States and Canada, its death toll is estimated at 6 million. In some areas, the disease is credited with wiping out 95 percent of bats.

Bats with the fungus act strangely during hibernation season, often going outside during the day – a time when they should be attached to cave walls, awaiting warmer climes. The disruption leaves the bats in a weakened state.

The affliction has implications for other species – notably, human beings. Bats are one of nature’s great insect-disposal machines. Scientists say they are responsible for saving U.S. agriculture billions every year. Those same bats saving farmers money also are helping keep back yards more habitable, cookouts more pleasant.

And, for some, bats are winged wonders. Pattavina is one.

When he saw all those bats three years ago in the heart of a mountain where workers had sweated a more than a century earlier, Pattavina was entranced.

“It was beautiful,” he said.

‘Not easy to see’

Katrina Morris, a biologist with the Georgia Department of Natural Resources, sat just in front of Pattavina as the aluminum craft nosed farther into the darkness. With her were DNR biologist Laci Coleman and Leanne Burns, a state bat conservation technician.

A biologist wearing a head lamp swabs a hibernating bat.

Bat specialist Leanne Burns checks out a tri-colored bat clinging to the wall of the Black Diamond Tunnel, an abandoned railroad project in the North Georgia mountains. Photo by Mark Davis, USFWS.

With Morris and Coleman holding lights, Pattavina periodically stopped the boat, grasping outcroppings on the tunnel’s cold ceiling. Burns took swabs from some sleeping bats to review in laboratories. She also took samples from the rock walls around selected bats. Annual surveillance at Black Diamond and caves across the U.S. and Canada give researchers an ideal of how prevalent the fungus is. It also helps assess certain amounts of fungus – “fungal load” – translates to effects on different bat species.

Pattavina lowered his paddle, pointed “There,” he said. “There’s one.”

The lights showed a brown figure, no larger than a computer thumb drive. Across its muzzle was a splash of white – proof that the infection had returned for another year to the unfinished tunnel.

Burns got busy – swab, measure. She moved quickly, murmuring findings to her colleagues.  Pattavina reached for his paddle. The boat moved on.

The recent survey was but one of scores Service biologists conduct. Pattavina recently was in Alabama, where volunteers hung from ropes 200 feet into the earth and counted bats. He also planned to visit an abandoned Georgia mine and do another bat inventory the day after his trip into the tunnel.

The count from the tunnel? When they returned from their trip into the darkness, the scientists totaled their findings: 152. A year earlier, they had counted 220.

Pattavina and Morris tried not to look dejected – tried, and failed.

“I guess we’re not too surprised,” Pattavina said.

Morris nodded. “Seeing about 30 more (bats) would make me feel better,” she said.  “It’s not easy to see this, year after year.”

Contact

Mark Davis  404-679-7291
Public Affairs Specialist