Bat studies in Indiana between 1961 and 1993 recorded bat roost locations. All of the roosts of evening bats were in buildings. Consequently, the fact that all evening bats radio-tracked since 1993 have roosted in trees was notable. The building roosts may have been the result of spillover from large populations of evening bats in the woods along rivers, where, prior to 1993, scientific data were not collected. The building roosts may also indicate that this species had adapted well to human structures. However, the disappearance after 1993 of previously known roosts in buildings suggests that this adaptation became less successful. Big brown bat populations have been increasing in Indiana, and perhaps evening bats do not compete successfully with them for roosts in buildings.