Movement Patterns of Migratory Bats during Autumn Migration

Abstract

Migration routes of long-distance migratory tree-roosting bats (Lasiurus cinereus, L. borealis and Lasionycteris noctivagans) in North America are poorly understood. Large numbers of bat fatalities recorded at wind energy facilities are contributing to likely population declines of these species. Most documented migratory bat fatalities at wind energy installations occur during autumn migration. There is some urgency to better understand migration patterns of these bats, because like many other jurisdictions, the Province of Saskatchewan plans to dramatically increase wind power generation capacity. I installed passive acoustic detectors in southern Saskatchewan during the migration period to measure migratory bat activity. I placed one set of detectors in a three-by-three grid pattern across the study area in locations with high wind energy potential and prominent landscape features. I installed a second set of detectors along 5 km transects perpendicular to four of the province’s major rivers. I found higher levels of migratory bat activity in the eastern portion of the province. Activity was also generally higher in riparian areas and decreased with distance from rivers. This pattern is consistent with access to resources such as roosting habitat and water being important in bat migration route selection. Sites located in riparian areas and the southeastern portion of the province contain more forested landscape than other sampling sites located in uplands and grassland ecoregions. These results will inform siting decisions for future wind energy projects.