(Uploaded by Plazi for the Bat Literature Project) Copperhead Cave is an abandoned mine in Vermillion County, Indiana, serving as both a hibernaculum and a swarming area for northern bats (Myotis septentrionalis), little brown bats A (M. lucifugus), and eastern pipistrelles {Pipistrellus subflavus). double-frame harp trap was used to document bat activity at the mouth of the mine on a weekly basis from the fall of 1989 to the spring of 1991. Most of the trapped bats were banded and released. Little brown bats of both sexes emerged gradually from hibernation between 14 March and 19 May 1990 and between 15 March and 1 May 1991. In contrast, northern bats emerged in much larger numbers between 9 March and 27 April 1990 and between 21 February and 22 April 1991. The mine served as a swarming area from the end of July to the end of October for both species of Myotis and through the first week of October for the pipistrelles. The pipistrelles exhibited almost no winter activity (flight). However, the little brown bats and the northern bats were active at the mine entrance throughout the winter. Turnover in the bat populations of this mine is quite high, as indicated by the low number of banded bats recovered: 336 of 1733 (19.4%) individuals of Myotis lucifugus; 174 of 2090 (8.3%) individuals of M. septentrionalis; and 100 of 546 (18.3%) individuals of Pipistrellus subflavus.