Hebron Elementary

Indiana Bat

Estimated Remaining Population:
Experts say that in the past, the population of the Gray Bat exceeded 7 million specimens. In 1980, the total population was estimated at 1,575,000 bats.

Reasons For Endangerment:
The main causes of the Gray Bat's decline are the disturbance of its habitat be amateur speleologists and the killing of bats be vandals. Also contributing to its endangerment is the drop in the number of mayflies, the bat's main food source, due to pollution of the waters and deforestation near the openings to caves. Other threats to the bat include the use of pesticides and collisions with gates at the entrances to caves. The gates were put up to keep people out.

Conservation Measures:
In 1976, the U.S. Department of the Interior considered the Gray Bat in danger of extinction, and laws were enacted to protect it. Measures were taken to protect all of the major caves used by the bats during the winter as well as the important sites where the famales give birth. The Gray Bat's future is still uncertain.

The Indiana Bat has a soft, fine, chestnut-colored coat on its back and a pinkish color under the belly.

*Length: 1.5 to 2 inches
*Weight: about .25 oz.
*Wingspan: 9 to 10 inches

The Indiana Bat lives in the eastern United States. Its general territory extends from New Hampshire in the northeast, to Alabama in the south, and as far west as Oklahoma. Some small colonies also are found in northwestern Florida. Members of this species gather in enormous colonies during the winter for hibernation.

This bat's favorite food is moths, but other insects also are an important part of its diet. It usually hunts for insects in foliage found along weterways and in forests.

Breeding Habits:
In the summer, pregnant female bats gather in small colonies in cavities of dead trees to give birth. Colonies usually are made up of about 25 females. Each gives birth to only one lffspring. Births occur at the end of June or the beginning of July.

Interesting Facts:
*The Indiana Bat travels distances of 22 to 300 miles to reach hibernation sites.
*It hibernates in the coldest parts of caves, where the temparature is between 36 and 46 F.
*If the bat wakes up during hibernation, it uses large amounts of stored body fat and jeopardizes its chance of survival.

Estimated Remaining Population:
In 1960, the Indiana Bat population consisted of about 640,000 specimens. In 1975, the population dropped 28% to about 460,000. The reduction was particularly evident in Kentucky, where the population decreased from 209,800 to 55,800. The total population grew to about 509,000 in 1978. In the winter of 1985-1986, three new colonies were found.

Reasons For Endangerment:
The primary reasons for this species' endangerment are human disturbance and inadequate protection of the caves where the bat resides.

Conservation Measures:
The Indiana Bat is protected by the 1973 United States Endangered Species Act in all of the states where it lives. A few of its caves and mines have gained the legal status of Critical Habitat. Others have become state or federal property, and now enjoy partial protection from the government.


Endangered throughout its range, Federal Register, March 11, 1967

The Indiana bat is a medium-sized myotis, closely resembling the little brown bay (Myotis lucifugus) but differing in coloration. Its fur is a dull grayfish chestnut rather than bronze, with the basal portion of the hairs of the back dull lead colored. This bat's underparts are pinkish to cinnamon, and its hind feet smaller and more delicate than in M. Lucufugus. The calcar (heel of the foot) is strongly keeled.

The Indiana bat occurs in the midwest and eastern United States from the western edge of the Ozark region in Oklahoma, to southern Wisconsin, east to Vermont, and as far south as northern Florida. In summer it is apparently absent south of Tennessee; in winter it is apparently absent from Michigan, Ohio, and northern Indiana where suitable caves and mines are unknown. About 500,000 individuals of this species still exist.

This bat has a definite breeding period that usually occurs during the first 10 days of October. Mating takes place at night on the ceilings of large rooms near cave intrances. Limited mating may also occur in the spring before the hibernating colonies disperse. Hibernating colonies disperse in late March and most of the bats migrate to more northern habitat for the summer. However, some males remain in the hibernating area during this period and form active bands which wander from cave to cave. Limited observations indicate that birth and development occur in vary small, widely scattered colonies consisting of 25 or so famales and their young. Birth usually takes place during June with each female bearing a single offspring. About 25 to 37 days are required for development to the flying stage and the beginning of independent feeding. Migration to the wintering caves usually begins in August. Fat reserves depleted during migration are replenished largely during the month of September. Feeding continues at a diminishing rate until by late November the population has entered a definite state of hibernation. The hibernating bats characteristically form large, tight, compact clusters. Each individual hangs by its feet from the ceiling. Every 8 to 10 days hibernating individuals awaken to spend an hour or more flying to join a small cluster of active bats elsewhere in the cave before returning to hibernation.

Limestone caves are used for winter hibernation. The preferred caves have a temperature averaging 37 degrees fahrenheit in midwinter, and a relative humidity averaging 87 percent. Some records are rather scarce. A few individuals have been found under bridges and in old buildings, and females and juveniles is limited to riparian and floodplain areas. Creeks are apparently not used if riparian trees have been removed. Males forage over floodplain ridges and hillside forests and usually roost in caves. Foraging areas average 11.2 acres per animal in midsummer.

Indiana bats are found over most of the eastern hald of the United States. However, large hibernating populations are found only in Indiana, Missouri, and Kentucky. Smaller populations of Indiana bats at either winter hibernation sites or at summer roost and maternity sites have been recorded from Alabama, Arkansas, Connicticut, Florida, Georgia, Illinois, Iowa, Maryland, Massachusetts, Michigan, Mississippi, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Vermont, Virginia, and West Virginia.




Bats, including Indiana bats, seem to play an important role in the ecosystems where they live. They may be important in controlling numbers of insects as this is their food soource. One of their prey species is the gypsy moth, an important forest pest. As sicj. they are biological insecticides that do not have the adverse affects caused by poisonous insecticides.



Managing for Indiana bats, particularly management for summer habitat, benefits the forest community and many wilodlife and aquatic animals and plants in that community. Management for IOndiana baty summer habitat includes ensuring that forested arteas along waterways remains forested. This helps aquatic species because forested stream and river banks filter sediments(and associated contaminants) during heavy rains which helps to maintain or improve water quality.

The Value of Dead and Dying


Management of summere habitat also includes ensuring that dead and dying trees are available, rather than harvesting all trees as they begin to die. This is very important for the forest community. Many wildlifespecies, other than Indiana bats, use dead and dying trees. Animals that use dead and dying trees include most woodpeckers, nuthatches, chickadees, screech owls, squirrels,and raccoons. Dead and dying trees are used by these animals as a food source (critters eat the bugs, fungi,and other organisms that cause decay) and as shelter(cavities). Also, as trees die and decompose, the logs provide food and shelteer for many animals and their decomposition adds nutrients to the forest soils. Forests that are harvested for commercial timber with trees being removed as soon as they begin dying, often require heavy doses of fertilizer to compensate for the nutrients that those soils are not getting from decomposing trees. Indiana bats are unattractive but fascinating creatures that have an important role in their ecosystems, benefit humans by eating nuisance and pest insects, and add to our biological diversity. Management for their habitat results in good forest management that benefits many aquatic and forest creatures.

Humphrey, Stephen R. A.R. Ritcher, and J.B. Coper. 1977. Summer Habitat and Ecology of the Endangered Indiana Bat, Myotis sodalis. J. Mammal. 58:334-346.
LaVal, R. K., R.L. Clawson, W. Caire. 1977. Foraging Behavior and Nocturnal Activity Patterns of Missouri Bats, With Emphasis on the Endangered Species Myotis grisecens and Myotis sodalis. J. Mammal.5800:592-599
LaVal,R.K., R.L. Clawsonl, W. Caire, L.R. Wingate, and M.L LaVal. 1976. An evaluatio of the status of Myotime Bats in the Proposed Meramec Park and Union Lake Project Areas , Missouri School of Forestry, Fisheries and Wildlife, University of Missouri, Columbia 136pp.
U.S. Department of Agriculture. 1975. Endangered, Threatened and Unique Mammals of the Southern National Forests. U.S. Forest Service, Atlanta, Georgia. 121pp.
U.S. Department of Interior. 1978. Species Accounts for Sensitive Wildlife Information System(SWIS). Fish


Written by: students

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Copyright August 1997 - Joan Goble and René de Vries

Last modified: May 10, 1998