Bioacoustic Monitoring Reveals Patterns of Landscape Use by Migrating Birds at a Great Lakes Barrier Crossing

Understanding how highly mobile animals use landscapes at broad geographic scales remains a major challenge in ecology. Traditional monitoring approaches often lack the spatial and temporal resolution to monitor how migratory species use heterogeneous landscapes, contend with movement barriers, and interact with urban and developed landscapes. Here, we use a passive acoustic monitoring network to characterize landscape use of migrating songbirds in the Keweenaw peninsula, a major barrier crossing point along the south shore of Lake Superior. Using nearly 3 million acoustic detections of migrants from 18 sites spanning 328 km², we demonstrate that landscape use is shaped strongly by local geography and wind conditions during reoriented movements associated with barrier crossing. Generally, more songbirds used the peninsula during wind conditions favorable for migration. Following winds unfavorable for crossing in spring, birds concentrated in coastal and ridge landscapes oriented along an east-west axis. Geographic gradients and coastline orientation both played important additional roles in shaping migrants' landscape use. Together, our results illustrate the complex role of large water barriers in shaping landscape use in highly mobile animals. More broadly, our findings demonstrate the value of acoustic monitoring as a novel technique for studying migratory animals' landscape use. This approach offers a powerful, scalable tool that can be deployed across complex landscapes and inform conservation priorities of hard-to-monitor species.