Long‐term monitoring of Indiana bats on the Fort Knox military base in Kentucky

Abstract Military installations are important refuges for sensitive species and are charged with conducting conservation measures for species’ habitat protection. The federally endangered Indiana bat Myotis sodalis was first documented at Fort Knox in northcentral Kentucky in 1998. We monitored this first documented colony and additional colonies on base from 2005–2021. By conducting multiple simultaneous emergence counts and banding bats at both natural and artificial roosts (e.g., BrandenBark®), we documented the two largest Indiana bat maternity colonies in the range of the species and two additional colonies that require additional study. An average of 102.5 ± 5.2 bats emerged per roost during 449 counts of 104 roosts. Emergence counts from BrandenBark® ( = 122.7 ± 8.0 bats per roost) were significantly greater than those from natural roosts ( = 71.6 ± 9.3 bats per roost), and 16 emergence events exceeded the published maximum emergence count of 384 bats. We tracked bats to 190 natural and artificial roosts. Most of the 158 natural roosts were green ash Fraxinus pennsylvanica or silver maple Acer saccharinum trees. There were no significant differences in roost tree diameter at breast height (dbh) or height compared to the dbh and height of trees in the plot around the roost, and there were no differences in roost dbh or height among reproductive periods. Home range sizes between the two main colonies were similar: 5,003.8 ha at the Cundiff Lake colony and 4,501.8 ha at the HA6 colony. We found that federal bounding dates for reproductive periods did not align with actual dates of reproduction at Fort Knox for pregnancy or post‐lactation, but there was no difference for the lactation period. The contiguous managed deciduous forest, abundant water sources, and proximity to large hibernacula make the roosting and foraging habitat at Fort Knox ideal for supporting large colonies of bats.