Myotis sodalis
Indiana bat

Indiana bats are found in the cavernous limestone areas of the midwestern, southern, and eastern United States. This range extends from the Ozarks of Oklahoma in the west, north to southern Wisconsin, as far east as Vermont, and as far south as northern Florida. During their winter hibernation, they are found throughout the Ohio Valley but are absent from southern Michigan, northern Indiana, and south of Tennessee (Thomson, 1982). Two hibernacula in Ohio have recently been reported: one in Lawrence County, another in Preble County, numbering upwards of 10,000 wintering bats. (U.S. Fish and Wildlife Service, 1991)

In winters, Indiana bats live in caves and mines that are appropriate for hibernation, with a cool, stable temperature. It is not clear where males are found and roost during the summer. Females and their young roost mainly under the loose bark of large trees (Thompson, 1982).

The body of Indiana bats is about the same size as a mouse (Baker, 1983), ranging in length from 73 to 100 mm and weighing 6 to 11 grams. Their dorsal fur varies from black to light brown, but the overall color is dull gray. Ventral fur has a pinkish-white tint to it (Thomson, 1982). The tragus is short and blunt (Baker, 1983). Females' forearms are, on average, larger than the males' (Thomson, 1982). These bats are similar in appearance to Myotis lucifugus, but differ in possessing a strongly keeled calcar and dorsal fur that is dull, rather than glossy, as in M. lucifugus. (Kurta, 1995; U.S. Fish and Wildlife Service, 1991)

Indiana bats live to be 14 years old in the wild. (Kurta, 1995)

In the early fall, Indiana bats swarm and mate at the hibernation sites. Bats enter the warmer parts of the cave and remain alert. For a while, they leave the cave at night to forage and build up body fat. During hibernation, they gather on a flat surface, either a ceiling or a wall. The groups are smaller in the warmer parts of the cave. These bats are known as "cluster bats" because they form large, dense groups during hibernation. As winter progresses, Indiana bats move to cooler parts of the cave. Those living in the warmer parts of the cave may wake up during hibernation and leave the roost before the winter ends. Normally, they leave the hibernation sites from April to June (Thomson, 1982). In the summer, males and females live apart from each other, with the females forming nursery colonies in hollow trees or under bark. Indiana bats leave their roosts about a half an hour after sunset to forage. They prefer to forage near the canopy in dense forests. (Kurta, 1995)

Home Range

In the summer, female Indiana bats have home ranges of about 52 hectares (128 acres). This range expands to 94 hectares (232 hectares) after the young are born. (Kurta, 1995)

Indiana bats use echolocation to find their way around. They use their vision for long distance homing and navigation. These bats have excellent hearing, and no doubt communicate with each other using sound.

The diet of Indiana bats consists of small, soft-bodied insects but may also include moths and beetles. The end of the summer correlates with the bats changing from eating soft to hard bodied insects (Thomson, 1982).

Indiana bats rarely have to fear predators. Their biggest threat is habitat destruction by humans. (Kurta, 1995)

Indiana bats have an important role in the ecosystem as consumers of large quantities of insects.

Like all bats, Indiana bats are potential reservoirs of diseases such as rabies and histoplasmosis.

Where large numbers are found, these bats help control populations of harmful insects.

Indiana bats are listed by the USESA, the IUCN red list, and the state of Michigan as endangered (Wilson, 1993). While fairly large numbers of individuals remain, they are restricted to very few caves during the winter and are therefore especially vulnerable to disturbance at those sites. The decline in populations over the past few decades is a result of natural disasters, human interference, and a changing microclimate in the hibernation caves. The range of the Indiana bat has decreased as well. Humans are working at increasing the population by protecting the existing roost sites and restoring habitats in the previous range (Thomson, 1982).

The hibernation caves of Indiana bats are popular tourist attractions. This is nice for humans, but the winter disturbance may not be good for the bats (Baker, 1983). You may be able to view a video clip of roosting Myotis sodalis at http://www.cavebiota.com.