To the Bat Cave
Over 60 eager and curious bat watchers recently took a short drive west of Chattanooga with Reflection Riding Arboretum and Nature Center educators to the edge of a historical, biological, and ecological treasure trove. The Nickajack Reservoir has played an important part throughout time, being a water highway for the Native Americans and Civil War soldiers, as well as an essential home to a diverse array of wildlife.
In particular, Nickajack Cave is a shelter for the endangered Gray Bat. Gray Bats are native to the southeastern United States and are the largest bat within their genus. Being picky about where to roost can make life difficult for these special mammals. These bats will not roost in barns or attics, instead picking only limestone caves near water. In Tennessee, there are only 8 caves that the Gray Bat inhabits. Such caves provide the perfect temperature to raise pups. Mating occurs in the fall and females enter hibernation soon after breeding. Females store sperm throughout the winter and become pregnant after emerging from hibernation. Pregnant females each deliver one young, usually in May or June. The young begin to fly after about 3 weeks and are weaned in July or August.
Gray bats are endangered largely because of their habit of living in very large numbers in only a few caves. As a result, they are extremely vulnerable to disturbance. Arousing bats while they are hibernating can cause them to use up a lot of energy, which lowers their energy reserves. If a bat runs out of reserves, it may leave the cave too soon and die. In June and July, when flightless young are present, human disturbance can lead to mortality as frightened females drop their young in the panic to flee from the intruder.
With Nickajack Cave right on the water, there are plenty of insects for a bat colony to eat (up to 3,000 per bat, per night!). Gray Bats feed on a variety of insects, but are partial to mayflies and stone flies. They will also eat mosquitoes, caddis flies, beetles, moths, flies, and other aquatic insects. Being in the limestone-rich area of south Tennessee on the Nickajack Reservoir, it’s no surprise that a colony of estimated 100,000 Gray Bats have chosen Nickajack Cave as their home.
The caves that Gray Bats inhabit are also coveted by others. Nickajack Cave provided shelter for Native Americans whose fires would smoke up the cave and disrupt the Gray Bats, causing them to leave or die. During the Civil War, soldiers discovered that Nickajack Cave had an abundance of saltpeter and guano, which they mined to make gunpowder. Disturbances to Gray Bat habitat occurring in caves across the United States has made it difficult for this unique species to survive keeping Gray Bats on the endangered list since 1976.
Nickajack Cave provides a unique and exciting opportunity for people to experience the beauty of the Gray Bats without causing them harm by walking out on a boardwalk to observe their emergence and flight. It’s always a treat to view an endangered species, learn about them and what can be done to help save them and it all happens right in our own backyard! That’s environmental education at its best!