Plants and Animals
Myotis sodalis Indiana bat
The Indiana bat is a small bat (average length 3.3 in/8.3 cm) with grayish brown fur, dark wing membranes, pinkish undersides, and short, rounded ears. It can be distinguished from similar Myotis species by a distinct elevated ridge or keel on the calcar (i.e., structure extending from the heel to support the back margin of the tail) and hind toe hairs that are shorter than the length of the toenail.
Status and Rank
US Status: LE - Listed Endangered
State Status: E - Endangered (legally protected)
Global Rank: G2 - Imperiled
State Rank: S1 - Critically imperiled
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Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Indiana bats roost and form maternity colonies under loose bark or in hollows and cavities of mature trees in the floodplain forest. In Michigan, savanna habitats adjacent to riparian corridors may have been historically important for roost sites, as the bats are thought to prefer sun-exposed trees for maximum warmth at the northern limit of their range. In winter, Indiana bats primarily hibernate in caves in Kentucky, Indiana, and Missouri, although a new hibernacula site has been found in northern Michigan at a hydroelectric facility.
Specific Habitat Needs
Snag/cavity needed in: Bur oak plains; Floodplain forest; Oak openings; Southern hardwood swamp.
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Floods, cave ceiling collapses, mortality during severe winters, and human disturbances (e.g. vandalism, caving, and indiscriminant collecting) have severely disrupted local populations at their hibernacula. The Indiana bat requires large blocks of mature floodplain forest, including standing snags and other suitable living roost sites. A primary limiting factor in their summer range has been the deforestation of riparian habitats, which usually occurs from the cutting of large, dead trees for firewood. Stream channelization, bank modification, and agricultural development along stream banks also have contributed to habitat destruction. Riparian habitat can be maintained by protecting mature, wooded areas, leaving large, dead trees standing, and maintaining wide vegetation buffer strips. Cutting of snags, canopy removal, and general land clearing activities along streams and rivers for development, agriculture, utility corridors, river or drain dredging and other purposes should be avoided. The species would likely benefit from restoration of floodplain forests and adjacent savannas through tree planting efforts.
Active from fourth week of March to fourth week of November
Breeding from first week of October to second week of October
Migration from fourth week of April to fourth week of May
Parturition from first week of June to first week of July
Mist nets should be set perpendicular to travel corridors such as streams, rivers, and logging trails. A typical net setup is 23-30 feet (7-9 meters) high and up to 66 feet (20 meters) wide. Surveys should consist of a minimum of 1 net site per 0.6 mile (1 kilometer) of habitat corridor and 2 sites per 247 acres (1 square kilometer) of habitat. Mist netting at a site should be conducted for four nights and in at least two different locations within a site. Nets should be checked every 20 minutes from sunset to sunrise. The species is most active 25 minutes after sundown to four hours after sundown.
Survey Period: From second week of May to second week of August
Time of Day: Evening
Time of Day: Night
- Kunz, T.H., ed. 1988. Ecological and Behavioral Methods for the Study of Bats. Smithsonian Institution Press, Washington D.C. 533pp.
- Kurta, A. 1980. Status of the Indiana bat, Myotis sodalis, in Michigan. Michigan Academy of Science 13:31-36.
- Wilson, D.E., F.R. Cole, J.D. 1996. Measuring and Monitoring Biological Diversity - Standard Methods for Mammals. Smithsonian Institution Press, Washington D.C.
- Baker, R.H. 1983. Michigan Mammals. Michigan State University Press, East Lansing.
- Evers, D.C. 1994. Endangered and Threatened Wildlife of Michigan. The University of Michigan Press, Ann Arbor. 412pp.
- Kurta, A. 1995. Mammals of the Great Lakes Region. The University of Michigan Press, Ann Arbor.