The Indiana bat resembles the little brown bat, but has a pinkish cast to its fur, giving it a light purple-brown coloration. Length, 2.9 - 3.7 inches; wingspread, 9.4 - 10.3 inches; weight, 0.18 - 0.28 ounces. Sexes are equal in size.
Indiana bats roost in trees in summer; and they do not commonly roost in buildings. In winter, some 97 percent of the total species population hibernates in certain large caves in Missouri, Kentucky, Indiana and Illinois. Pennsylvania is on the fringe of the species’ range. Indiana bats have been found wintering in 12 sites (caves, as well as abandoned mines and railroad tunnels), and are monitored regularly by the Game Commission. The Indiana bat is on the federal endangered species list.
The Indiana bat hibernates in clusters of bats on the ceilings and side walls of caves. In this formation, it is vulnerable to disturbance by cave explorers: when a bat on the edge of the cluster is awakened, it moves about, starting a ripple of activity that spreads throughout the group. A winter of repeated disturbances causes bats to burn vital fat stores, and they may run out of energy before spring.
Females of this species are believed to bear a single young in late June.