Indiana Bats in the Midwest: The Importance of Hydric Habitats

Abstract

The endangered Indiana bat (Myotis sodalis) requires very specific habitats to provide necessary day-roosting and foraging resources during the spring and summer months throughout its distribution in the eastern United States. Maternity colonies of Indiana bats are almost always found under the exfoliating bark of dead or dying trees. Furthermore, they switch frequently among multiple roosts within large but still somewhat local areas. Therefore, habitats with large numbers of snags or decadent trees are needed to support Indiana bat maternity colonies. These habitats arise naturally and anthropogenically in a variety of ways. However, these conditions often are rare relative to other forest conditions. In the Midwest, such as southern and central Illinois, USA, maternity colonies are more commonly associated with bottomland, riparian, wetland, or other hydric forest types. It is unclear if this occurs because areas with large numbers of snags are more common in these habitats, if maternity colonies prefer these habitats for their foraging resources, or if decades of intensive agriculture have restricted colonies to these habitats. Because many large maternity colonies have been observed in hydric habitats of the Midwest, I hypothesize that these are preferred maternity habitats. Moreover, very few large maternity colonies have been located using upland forest habitats within the region. Elsewhere, such as in the central and southern Appalachians, maternity colonies have been located in upland areas where bottomland habitats are less extensive. However, these colonies are usually characterized by small numbers of bats and ephemeral persistence. Future conservation efforts for the Indiana bat should focus on protecting and regenerating bottomland habitats along the major river systems of the midwestern United States. It is within these bottomland and riparian habitats that future large and long-term maternity colonies will be established.