In especially cold caves like Schoolhouse, where temperatures rarely exceed 48 degrees in summer, but hover near the freezing point in winter, maternity colonies gather in clusters that can contain 500 or more individuals. In summer, the bats shelter in caves, but range outside to feed on moths and other insects. Using radio telemetry, Stihler and Wallace have tracked the bats as they leave their caves on summer nights to forage. They have been known to travel up to seven miles on their feeding flights. The numbers of the rare bats declined sharply from the 1950s to the early 1980s.
Biologists believe human disturbance was the main cause for the population drop.
The big-eared bats are more sensitive to disturbance than other bat species, and are easily awakened from hibernation. Each time they are rousted from their slumber, they use up a portion of their small reserve of stored fat. Repeated winter disturbances can cause death from starvation. Disturbances during the summer can cause female bats in maternity colonies to drop their pups, which they cannot retrieve from the cave floor. As part of the recovery program for the endangered bat, the DNR, in cooperation with property owners, caving organizations, the U.S. Forest Service and the Fish and Wildlife Service, has installed gates blocking access to caves containing critical Virginia big-eared bat populations.