Migratory Tree Bat Roost-Site Use and Movements

Silver-haired (Lasionycteris noctivagans) and hoary (Lasiurus cinereus) bats are migratory, tree-roosting bats frequently encountered during post-construction fatality searches at wind energy facilities. Basic biological... [ view full abstract ]

Silver-haired (Lasionycteris noctivagans) and hoary (Lasiurus cinereus) bats are migratory, tree-roosting bats frequently encountered during post-construction fatality searches at wind energy facilities. Basic biological information such as tree characteristics associated with their roost sites, and local and migratory movements are poorly understood. Understanding the tree and landscape characteristics associated with migratory tree bat roosts and movements during the summer season could help inform the siting of wind energy development. Furthermore, access to migratory bat species during the summer residency period and recent advances in GPS tag technology provides an opportunity to examine migratory movements of these species. We captured and placed VHF transmitters on migratory tree bats in the Rocky Mountains of western Montana during the summer to identify day roosts, characterize the vegetation associated with these roosts, and assess daily fidelity to day roost locations. We also marked individual bats with PIT tags to provide the foundation for understanding inter-annual fidelity to summer habitats, and possibly migration pathways through studies in subsequent years. This project provided the first documented roost locations and descriptions for this species in Montana and one of the first known efforts to quantify roost-site fidelity within the summer season. The preliminary results presented here represent the first year of a three-year study. The second year of this study will include attaching GPS transmitters onto bats to determine migratory movements between summer residency periods. Subsequent recoveries of individually marked individuals in mist nets or at wind energy facilities, may also help to piece together movements of these species.