This document is one in a series of U.S. Army Engineer Research and Development Center (ERDC) technical notes produced under the Ecosystem Management and Restoration Research Program (EMRRP). The technical notes identify sensitive species potentially impacted by U.S. Army Corps of Engineers (Corps) reservoir operations and are products of the EMRRP work unit entitled "Reservoir Operations - Impacts on Habitats of Target Species" (Dickerson, Martin, and Allen 1999; Kasul, Martin, and Allen 2000). This technical note provides information on selected bat species that have the potential to occur on Corps projects in the eastern United States and be impacted by Corps activities. It is linked to another technical note (ERDC TN-EMRRP-SI-24) that presents an overview of general habitat requirements, impacts, and management needs for these species. Although Townsend's big-eared bat (Corynorhinus townsendii) consists of five subspecies, this document focuses on the Ozark (C t. ingens) and Virginia (C. t. virginianus) big-eared bats because of their federally endangered status. The ecology, legal status, potential impacts, and management guidelines are described primarily for these eastern subspecies.