The Night Shift

Biologists Survey Forest-Loving Bats

It was 1 a.m. The sticky air had cooled to the 70s and the darkness vibrated with the deafening whir of katydid song.

“Where's your booty, sir?” Emily Doub, Tennessee Valley Authority terrestrial biologist, asked the bat.

She aimed her headlamp on the animal and delicately maneuvered it backward through the fine threads of the survey net.

Tyler Pesce, field technician for Borealis Biological, one of TVA’s conservation partners worked next to her.

“You want to take the net off almost like a T-shirt,” Pesce said. “Off their bottom, off their tail, then over their elbows.”

Gently, Doub untangled bony bat knuckles while the animal gnawed her gloved fingers with razor-sharp teeth. Once freed, each bat went into a bag for quick measuring and release back into the trees.

This night bat survey, near Chatuge Dam in southwestern North Carolina, is one of many across TVA’s seven-state service area. It helps biologists protect habitat for bats and other wildlife living near TVA’s dams, transmission lines, power generation sites and other lands.

“As a federal entity, we comply with the Endangered Species Act,” Laura Vining, TVA biologist, explained.

“And we go above and beyond,” Doub said. “We actively want to better understand species so we can avoid impacts to them. (Partners) help with that. Every person who works on these projects is a passionate biologist."

Michelle Gilley, Ph.D., president and co-founder of Borealis Biological, and Tyler Pesce, field technician for Borealis Biological, untangle a bat from a mist net.

Meticulous Measurements

It takes passion – as well as certifications, rabies vaccinations and a lot of caffeine – to monitor bats through the night.

Hours earlier, at sundown, the biologists had stretched a pair of 20-by-15-foot mist nets – woven of the finest black threads – like a spiderweb between maple and pine trees.

Then they waited.

Every 10 minutes, wearing headlamps, face masks and latex gloves over leather ones, they checked for hamster-size bats cradled in the net’s pocket folds.

“Red bat, male,” Doub called.

“Big brown, female,” Vining said.

They slipped the bats into small bags and transported them to the measuring station.

“Every bat we catch, we determine sex, age, and reproductive status,” Dr. Michelle Gilley, president and co-founder of Borealis Biological, said.

The feisty bats bit and chirped as the biologists crooned, cradling them "burrito-style," Pesce explained, as they took measurements.

Gilley shone a light through each bat’s joints to assess its age. Juveniles have open knuckles like the eye of a needle, while adult knuckles are fused. She measured each bat’s right forearm, checked to see if it was male or female and, when female, if she was still nursing pups.

“We also do a wing index score based on the amount of blotchiness or scar tissue,” Gilley explained, bending over one bat.

The fungus that causes white-nose syndrome damages a bat's tender skin while it hibernates in winter. Scars from a healed infection trace across the delicate wings and nose in the summertime.

On this night, most bats showed signs of a past infection.

So Gilley took a final step to protect each one. She scanned a black light across the stretchy wings and tail and across the downy fur of its face. That helps kill the fungus.

Finally, the biologist stepped toward the forest and opened her hands – and the bat, chattering, swooped away.

Gilley measures bat wings and checks their health.

Bat Backpacks

Bat survey work has never been so important.

Since 2006, white-nose syndrome has decimated bat populations across the U.S., pushing some species onto the Fish and Wildlife Service’s endangered species list for the first time.

Even though their work eating bugs, pollinating and spreading seeds happens invisibly, in the veil of night, bats play a key role in ecosystems.

On this visit, the biologists found large insect-eating Eastern red and big brown bats, but they had the potential to catch several other species that have become less common, too – tiny tricolored (formerly known as pipistrelles or ‘pips’), hoary, little brown and the endangered Indiana bat.

Finding threatened or endangered species would trigger another step: tracking.

That involves fitting bats with a small, temporary transmitter that’s only a tiny percentage of the bat’s body weight, Vining explained.

“(It goes) right between their shoulder blades on their back,” Gilley said. “They end up looking like remote-control bats because they have a little antenna.”

The human-grade surgical glue biologists use dissolves in about a week.

“It just naturally falls off,” Gilley said. “(And) these are all social bats, so sometimes their friends will groom it off for them.”

Antenna receivers allow researchers to plug in a bat’s frequency – like tuning in a radio station – to listen for increasingly loud beeps and find its exact location.

When they find the bat, they’ve found the roost tree where mothers raise their pups. This helps TVA know which trees to protect for the future, Gilley explained.

“TVA does a great job serving as an environmental steward of its properties,” Gilley said. “It's great to collaborate with agencies like TVA and the U.S. Fish and Wildlife Service that are passionate about wildlife conservation.”

“When you put all the pieces of the puzzle together, the consulting firm, the state agencies, the Fish and Wildlife Service and the client can all work together to come up with the best management plan,” Gilley continued. “What's good for the bats?”

Doub explained that TVA works to protect other species, as well.

TVA maintains a buffer distance around bald eagle and osprey nests, for example. They work with partners to build road crossings for four-toed salamanders and time their projects to minimize impact on animals.

“We’re defending the species we care about,” Vining said.

Doub agreed.

“We want to be able to provide power to the Valley with growing demand (and) … still maintain our environmental integrity,” she said.

The team uses a black light to kill fungus that causes white-nose syndrome on the bat’s skin.

A Conservation Mindset

By 1:50 a.m., the crew lowered the nets. Borealis Biological’s biologists carefully folded them into color-coded bags for easy unfurling the next night.

Ten bats total had flown into the mist nets. A good number, but not as many – and not the species – as they would have caught in the past.

“Before white-nose, if you were in a good spot like this where you’re connecting a river to a lake, we’d catch 30 bats,” Gilley said. “White-nose syndrome has put a damper on population numbers and diversity.”

“We barely ever see little browns anymore,” Doub said.

Gilley nodded.

“It used to be one of the most common bats that I caught,” she said. “Now it’s (mostly) reds or big browns.”

Across the Southeast and TVA’s seven-state service area, biologists doing forest surveys in summer and cave surveys in winter have noticed the same trend. Some species, such as big brown bats, are more likely to survive white-nose syndrome. Yet some smaller bats are disappearing, edging closer to extinction.

“You can't ever say, ‘I’m tired of seeing this bat,’” Vining said. “You never know when it’s going to disappear.”

Photo Gallery

The land below Chatuge Dam offers ideal habitat for bats, with access to water, trees and open areas where the animals can forage for insects.

The bat team checks the nets every 10 minutes and carefully removes each bat to check their health and take measurements. Then the bats fly free again.

Pesce readies a bag to safely transport a bat from the net to the measurement station.

Gilley weighs each bat in its bag before gently removing them to measure wingspan and assess health.

TVA terrestrial zoologist Laura Vining measures a bat.

Bat wings are a different version of "hands," with delicate skin stretched between the finger bones. They’re the only true flying mammal in the world.

PHOTO AT TOP OF PAGE: TVA terrestrial biologist Emily Doub evaluates bat wing health as part of a mist net survey at Chatuge Dam.