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Indiana bat

Myotis sodalis

What do they look like?

Indiana bats are small, weighing about 7 g and with a forearm of 35 to 41 mm. They are dark grey or brown with soft fur. They look very similar to little brown bats, but have softer fur that is less shiny. However, they are so similar that only experts can really tell them apart. Male and females look very similar, but females are a little bit larger. (Barbour and Davis, 1969; Whitaker and Hamilton, 1998)

  • Sexual Dimorphism
  • female larger
  • Range mass
    5 to 11 g
    0.18 to 0.39 oz
  • Range length
    70.8 to 90.6 mm
    2.79 to 3.57 in
  • Average length
    81.7 mm
    3.22 in
  • Range wingspan
    240 to 267 mm
    9.45 to 10.51 in

Where do they live?

Indiana bats only live in North America. They are found in Iowa, Missouri, and northern Arkansas, east to western Virginia and North Carolina, and north into New York, Vermont, New Hampshire, and Massachusetts. These states include both their winter hibernation locations and summer homes. Indiana bats spend the winter hibernating in caves in the northern parts of these areas. In the summer and fall, they travel to and from summer roosting locations. (Kurta, et al., 2002; Thomson, 1982)

What kind of habitat do they need?

Indiana bats mostly in limestone caves, though some hibernate under the bark of dead trees. During the summer, Indiana bats roost during the day under the bark of large trees, under bridges, and sometimes in buildings. Trees in which Indiana bats are known to roost include bitternut hickory, oaks, elms, pines, American sycamore, and eastern cottonwoods. In summer, they roost at elevations from 0 to 1,746 m above sea level. The average summer elevation is 1,047 m. (Barclay and Kurta, 2007; Brack, et al., 2002; Butchkoski and Hassinger, 2002; Gardner and Cook, 2002; Tuttle and Kennedy, 2002)

  • Other Habitat Features
  • caves
  • Range elevation
    0 to 1,746 m
    0.00 to ft
  • Average elevation
    1,047 m
    ft

How do they reproduce?

Male Indiana bats mate with multiple females. They wait for females at the entrance to their winter hibernation location during their big gathering in October or November, which is called a fall swarm. (Whitaker and Hamilton, 1998)

Indiana bats breed in the fall, usually in late October right before they begin to hibernate. Females don't get pregnant until spring, and the young are born in the summer. Females give birth to only one pup per year, but in rare cases can have twins. Most pups are born between late June and early July and drink their mother's milk for about 31 days. This can be as few as 25 and as many as 37 days. The first born pup of the season can fly as early as the middle of July. (Barbour and Davis, 1969; Barnard, 2009; Fenton, 1985; Whitaker and Hamilton, 1998)

  • How often does reproduction occur?
    Indiana bats breed once yearly.
  • Breeding season
    Copulation generally occurs in October, before hibernation.
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    68 (high) days
  • Range weaning age
    25 to 37 days
  • Range time to independence
    2 to 3 months

Females care for pups after they are born at summer roosting sites. They often form maternity colonies, which are groups of almost only mothers and their pups. Females feed the pups milk from their bodies for about 31 days. After 2 to 3 months, pups are fully independent from their mothers. (Whitaker and Hamilton, 1998)

  • Parental Investment
  • altricial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

How long do they live?

Indiana bats have lived as long as 20 years in the wild. Their expected lifespan in the wild is 15 years. (Miller and Allen, 1928)

  • Range lifespan
    Status: wild
    20 (high) years
  • Typical lifespan
    Status: wild
    15 (high) years

How do they behave?

Indiana bats are social, which explains their other common name, "social myotis." They don't have social hierarchies, however. Males and females hibernate together in the winter, but adults separate in the summer months when females and their young join maternity colonies. Indiana bats migrate from winter hibernation location to summer roosts, traveling up to thousands of kilometers. They forage over a wide area during the summer months. (Gardner and Cook, 2002; Pierson, 1998; Whitaker and Hamilton, 1998)

  • Range territory size
    2 to 8 m^2

Home Range

The area Indiana bats travel and feed in changes depending on the bat and the time of year. Home ranges are about 625 hectares during the fall, and 255 hectares in the spring. They don't defend their home ranges, but mothers may defend a maternity colony from potential threats that come within 5 sq m. (Romme, et al., 2002; Whitaker and Hamilton, 1998)

How do they communicate with each other?

Like other insect-eating bats, Indiana bats find their way through their habitats using echolocation. This means that they listen to echoes to figure out where insects and obstacles are. Indiana bats have good eyesight which helps them migrate between summer and winter locations. They don't seem to communicate with each other by sound, but do use chemicals to communicate for reproduction. (Linzey, 2001)

What do they eat?

Indiana bats eat lots of insects. They mostly eat beetles, flies, bees and wasps, butterflies and moths, and caddisflies. Females eat different kinds of insects depending on whether they are pregnant or nursing. In the south, they eat more insects on land, and northern Indiana bats eat more insects from wetlands. (Linzey, 2001; Murray and Kurta, 2002)

  • Animal Foods
  • insects

What eats them and how do they avoid being eaten?

Predators that eat Indiana bats include snakes, owls, raccoons, and other medium-sized mammals. Indiana bats avoid predators by roosting in caves and tree crevices. They are also active at night and quick in flight. Their camouflage coloration also helps to protect them from predators. (Hart, 2010; Mohr, 1976; Whitaker and Brack, 2002; Whitaker and Hamilton, 1998)

Humans don't eat Indiana bats, but sometimes kill them. For example, at Carter Caves State park in Kentucky, two men clubbed 105 Indiana bats to death. Humans also unintentionally kill bats by destroying or cutting down trees they roost in or disturbing hibernation sites. (Hart, 2010; Mohr, 1976; Whitaker and Brack, 2002; Whitaker and Hamilton, 1998)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Indiana bats help control insect populations and are prey for bat predators. Some kinds of mites (Steatonyssus occidentalis and Macronyssus crosbyi) live on their bodies, but they don't seem to get parasites inside their intestines. They add nutrients to their cave environments, including their body waste and the nutrients from their bodies when they die. (LaRoe, et al., 1995; Whitaker and Mumford, 1971; Whitaker, 1973)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • mites (Steatonyssus occidentalis)
  • mites (Macronyssus crosbyi)

Do they cause problems?

Indiana bats can become a nuisance if their summer roosting location is destroyed and they move into homes or attics. Like most mammals in the United States, Indiana bats also may be carriers of rabies. However, rabies infection in Indiana bats is rare, and usually humans wouldn't be close enough to them to get it anyway. (Butchkoski and Hassinger, 2002)

  • Ways that these animals might be a problem for humans
  • injures humans
    • carries human disease

How do they interact with us?

Indiana bats may impact humans by helping to control pest insect populations. (Whitaker and Hamilton, 1998)

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

Indiana bats are endangered according to the IUCN Red List and the U.S. federal list. They are mostly threatened by habitat loss, so their numbers are monitored. Any organization wanting to change a section of their habitat has to accommodate them specially. Humans also disturb Indiana bats through exploring caves for fun, so many of the caves where they hibernate are now closed off to humans. ("Indiana Bat (Myotis sodalis) Draft Recovery Plan: First Revision", 2007; Gargas, et al., 2009)

Like many North American bats, Indiana bats are threatened by a disease called “white-nose syndrome,” where a fungus grows on their noses while they are hibernating. This causes the bats wake up from hibernation and use up all of their energy resources. It has killed many bat populations since it was discovered in 2007. At some hibernation locations, as many as 90% of bats have died from the fungus. ("Indiana Bat (Myotis sodalis) Draft Recovery Plan: First Revision", 2007; Cryan, 2010; Gargas, et al., 2009)

Contributors

Anna Burgess (author), Radford University, Gail McCormick (editor), Animal Diversity Web Staff, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor, Catherine Kent (editor), Special Projects.

References

U.S. Fish and Wildlife Service. Indiana Bat (Myotis sodalis) Draft Recovery Plan: First Revision. Fort Snelling: Fort Snelling. 2007.

Barbour, R., W. Davis. 1969. Bats of America. Lexington, Kentucky: The University Press of Kentucky.

Barclay, R., A. Kurta. 2007. Ecology and Behavior of Bats Roosting in Tree Cavities and Under Bark. Pp. 17-50 in M Lacki, J Hayes, A Kurta, eds. Bats in Forests: Conservation and Management. Baltimore: The Johns Hopkins University Press.

Barnard, S. 2009. Maintaining Bats for Captive Study. Pp. 351 in T Kunz, S Parsons, eds. Ecological and Behavioral Methods for the Study of Bats. Baltimore: The Johns Hopkins University Press.

Brack, V., C. Stihler, R. Reynolds, C. Butchkoski, C. Hobson. 2002. Effect of Climate and Elevation on Distribution and Abundance in the Midestern United States. Pp. 21-28 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Butchkoski, C., J. Hassinger. 2002. Ecology of a Maternity Colony Roosting in a Building. Pp. 130-142 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Clawson, R. 2002. Trends in Population Size and Current Status. Pp. 2-8 in A Kutra, J Kennedy, eds. The Indiand Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Cryan, P. 2010. "White-nose syndrome threatens the survival of hibernating bats in North America" (On-line). U.S. Geological Survey, Fort Collins Science Center. Accessed September 20, 2012 at http://www.fort.usgs.gov/WNS.

Currie, R. 2002. Response to Gates at Hibernacula. Pp. 86-99 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Fenton, M. 1985. Communication in the Chiroptera. Bloomington: Indiana University Press.

Gardner, J., E. Cook. 2002. Seasonal and Geographic Distribution and Quantification of Potential Summer Habitat. Pp. 9-20 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Gargas, A., M. Trest, M. Christensen, T. Volk, D. Blehert. 2009. Geomyces destructans sp. no. associated with bat white-nose syndrome. Mycotaxon, 108: 147-154.

Hallam, T., P. Federico. 2009. Application of Dynamic Population Models to Bats. Pp. 184 in T Kunz, S Parsons, eds. Ecological and behavioral methods for the study of bats. Baltimore: The Johns Hopkins University Press.

Handley Jr., C. 1991. Virginia's Endangered Species. Blacksburg, Virginia: The McDonald and Woodward Publishing Company.

Hart, K. 2010. "Bat killers sentenced in federal court" (On-line). Accessed December 01, 2010 at http://dailyindependent.com/local/x434655806/Bat-killers-sentenced-in-federal-court.

Kiser, J., J. MacGregor, H. Bryan, A. Howard. 2002. Use of Concrete Bridges as Nightroosts. Pp. 208-215 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Kurta, A., S. Murray, D. Miller. 2002. Roost Selection and Movements Across the Summer Landscape. Pp. 118-129 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

LaRoe, E., G. Farris, C. Puckett, P. Doran, M. Mac. 1995. Our Living Resources: a report to the nation on the distribution, abundance, and health of U.S. plants, animals, and ecosystems. Washington DC: U.S. Department of the Interior, National Biological Service.

Linzey, D. 2001. Vertebrate Biology. New York: McGraw-Hill.

Miller, , Allen. 1928. Indiana Myotis: Myotis Sodalis. Pp. 205-211 in M Trani, W Ford, B Chapman, eds. The Land Manager's Guide to Mammals of the South. Durham, NC: USDA Forest Service, Southern Region and The Nature Conservancy.

Mohr, C. 1976. The World of the Bat. Philadelphia and New York: J. B. Lippincott Company.

Murray, S., A. Kurta. 2002. Spatial and Temporal Variation in Diet. Pp. 182-192 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Pierson, E. 1998. Tall Trees, Deep Holes, and Scarred Landscapes: Conservation Biology of North American Bats. Pp. 312-313 in T Kunz, P Racey, eds. Bat Biology and Conservation. Washington and London: Smithsonian Institution Press.

Romme, R., A. Henry, R. King, T. Glueck, K. Tyrell. 2002. Home Range Near Hibernacula in Spring and Autumn. Pp. 153-164 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Thomson, C. 1982. Myotis sodalis. Mammalian Species, 163: 1-5.

Tuttle, M., J. Kennedy. 2002. Thermal Requirements During Hibernation. Pp. 68-78 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Viele, D., A. Kurta, J. Kath. 2002. Timing of Nightly Emergence. Pp. 199-207 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Whitaker, J. 1973. External Parasites of Bats of Indiana. The Journal of Parasitology, 59/6: 1148-1150.

Whitaker, J., V. Brack. 2002. Distribution and Summer Ecology in Indiana. Pp. 48-54 in A Kurta, J Kennedy, eds. The Indiana Bat: Biology and Management of an Endangered Species. Austin, Texas: Bat Conservation International.

Whitaker, J., W. Hamilton. 1998. Mammals of the Eastern United States. Cornell University Press: Comstock Publishing Associates.

Whitaker, J., R. Mumford. 1971. Notes on a COllection of Bats Taken by Mis-Netting at an Indiana Cave. American Midlans Naturalist, 85/1: 277-279.

Whitaker, J., C. Ritzi, C. Dick. 2009. Collecting and Preserving Bat Ectoparasites for Ecological Study. Pp. 813 in T Kunz, S Parsons, eds. Ecological and Behavioral Methods for the Study of Bats. Baltimore: The Johns Hopkins University Press.

 
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Burgess, A. 2012. "Myotis sodalis" (On-line), Animal Diversity Web. Accessed September 02, 2014 at http://www.biokids.umich.edu/accounts/Myotis_sodalis/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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