MARION COUNTY, Tenn. (WKRN) – Nickajack Cave is one of Tennessee’s most fascinating hidden gems. From saltpeter mining during the Civil War to Johnny Cash’s spiritual experience inside its caverns, there’s a lot of history that happened in this cavern. The cave is also home to many bats, particularly the federally-endangered gray bat.

Elizabeth Hamrick, a Terrestrial Zoologist for the Tennessee Valley Authority (TVA), spends a lot of time learning about the gray bat colony inhabiting Nickajack Cave.

The cave partially flooded when TVA finished the Nickajack Dam in 1967, changing this scenic spot forever. “Most of the cave is now inaccessible, at least to humans. So there’s we haven’t figured out exactly what’s still underwater and what’s above water yet,” says Hamrick.

Gray bats, however, still have easy access to the cave, and it’s the home of a maternity colony during the summer months. They come in droves to roost, “the front part of the cave has this beautiful high dome in it, and that is what our federally endangered grey bats love for the summertime when they’re having their babies. They are attracted to warm caves with this high dome area where they can have their babies keep them at the right temperature, right humidity, and where they can cluster together.”

During the summer, these mother gray bats emerge from the mouth of the cave to forage and then return to feed their young. “There’s just this mass emergence, which is really beautiful to watch,” said Hamrick.

According to Hamrick, mother gray bats can find their pups out of thousands, “They’ll come back in several hours later and find their pups amongst, you know, amongst 1000s of other pups, they’ll find that one, and then they’ll be able to feed that one out of all the all the 1000s that are hanging right there in the dark.”

Once severely threatened by human development and white-nose syndrome, the gray bat population has rebounded in recent years. “If you take time to protect the species, you can help with the recovery of a species. And you can provide a safe place for you know, birthing 50,000 pups annually.”

Having a healthy population of bats at Nickajack has wide-reaching, positive impacts. “They have been documented to provide billions of dollars in ecosystem services for farmers by eating agricultural pests that otherwise farmers would have to use pesticides and other means to get rid of,” said Hamrick.

Each summer TVA hosts its annual bat count to help raise awareness about gray bats and keep tabs on their population. So if you’re looking for a summertime activity, you might want to consider participating.