Bringing Back the Bats

Several species of bats are flying onto the threatened and endangered species lists at alarming speed. That’s why TVA has installed artificial roost habitats intended to boost bat populations in the Valley.

Bats get a bad rap. After all, they’re often portrayed as spooky, freaky or downright nasty, when in truth they’re our helpful neighbors. Unless seriously molested, bats are peaceful and quiet, and bats in our area eat bugs, not blood—feasting on moths, flies, beetles and mosquitos. In fact, the more you understand about bats, the more you want them around.

Which is a bit unfortunate, as several species of bats in the Tennessee Valley have recently made their way onto the endangered and threatened species lists (or will be evaluated for listing in the near future), including the Indiana, the northern long-eared, the tricolored and the little brown bat.

Going Batty

“White nose syndrome [see sidebar] is taking a toll on these bats,” explains Heather Hart, senior specialist in Natural Resource Conservation at TVA who’s managing a project to install artificial roosting habitat to improve bat populations throughout the Valley. “At the same time, because they roost in exfoliated bark on dead or dying trees, they’re losing summer habitat to storms and to human development.” These are, by their nature, the very trees most likely to fall or to be cleared out in the name of progress.

Hart explains that these dwindling bat populations are a cause worth championing. “Not only do the bats help control insect populations, their guano provides key nutrients to the soil,” she says. “There are also other species—insects and other little critters—that use their guano for fuel. They are a link in the natural chain in the Tennessee Valley. We can’t afford to have them wiped out.”

There is no easy solution; nor is there a quick fix. Female bats typically bear only one young in May or June each year, and though avoidance is always preferable, it’s not always in alignment with the overarching human need for development. TVA itself has bumped up against bat populations in the installation of its transmission lines, which require tree removal.

What to Do?

Hart has identified an alternative: the installation of artificial bat roost structures designed for safe and secure long-term habitation by one of the most at-risk species, the Indiana bat. Far from the more familiar—and largely ineffective—bat houses, these structures include untreated utility poles covered with a layer of tough synthetic bark (called Brandenbark) installed over a grid-like surface designed to help bats cling with their feet and “hang in there.”

The overall effect is to recreate all the visual cues bats need when searching for a new home, and make it versatile enough to be installed in the locations bats love best—namely floodplains and upland forests. “You want to put these at the edge of the woods, near water and decent solar exposure—hopefully in areas where bats were known to have once inhabited,” Hart explains. “If you get the conditions right, they can start to inhabit one of these roosts in just a few months; in some rare cases, a few days.”

Starter Homes

Since May of 2016, Hart has worked with Liz Hamrick, terrestrial zoologist in TVA Biological Permitting and Compliance, and with Copperhead Consulting Services to oversee the installation of roosts on TVA sites throughout the Valley. They chose four locations to put 25 roosts: a transmission right of way at Big Sandy in Benton County, Tenn.; the Cave Mountain Small Wild Area on Guntersville Reservoir; Loyston Point on Norris Reservoir; and Marbut Bend Trail in Limestone County, Ala.

“Each of these roosts could host anywhere from 70 to 100 bats,” Hart explains. “The thought is that they would come back to the area and inhabit these, and that these would give the bats an opportunity to be sustained and continue to exist.”

The current program is a pilot, in observation phase now. “If these work, we will expand on the program—they are a simple, cost-effective way to provide instant habitat, and we can certainly use them to be proactive in our own activities,” Hart says. TVA will also be proactive in sharing findings with other government agencies and private entities in the interest of saving the species.

Holy Bat Count, Batman!

Each year, TVA employees do a bat count at certain caves to keep track of the numbers. This year, our Nickajack Cave gray bat count near South Pittsburgh, Tennessee, had a grand total of 72,068 bats. That’s up about 2,000 from 2017. Check out our night-vision video here!

What is White Nose Syndrome?

White nose syndrome (WNS) is a fungal disease that can decimate bat populations and has killed millions of bats in North America. WNS is cause by Pseudogymnoascus destructans, which invades the skin of hibernating bats, covering their muzzles, compromising their immune systems and disrupting their hibernation cycles. WNS causes them to wake repeatedly when they should be hibernating, which in turn causes them to expend energy and burn up their fat reserves. They end up leaving their hibernation areas looking for food—which isn’t available because it is winter—and starving or freezing to death. To see if WNS has been found in your county and for information about you can help stop the spread of the disease, visit