Spatial and species-specific variation in lake-crossing behavior in the Great Lakes region influences collision risk with offshore wind development

Abstract Millions of migratory birds are funneled through the Great Lakes region annually and depend on shoreline habitats for stopover and refueling, often crossing over open water in their movement north. Contrary to single species studies, an environmental assessment for proposed offshore wind development in Lake Erie found low frequencies of crossing and therefore low collision risk to migratory birds. Given the region’s high potential for offshore wind development, this discrepancy highlights the need to understand the frequency of lake crossing by migratory birds to assess collision risk for migrating birds. Using automated radio telemetry and the Motus Wildlife Tracking System, we followed individuals from a suite of study species, deploying tags at inland stopover locations spanning longitudinally from western Ohio to western Pennsylvania. Analysis of these movements showed regional differences in lake crossing frequency and regional movements, with birds tagged in central Ohio exhibiting the highest frequency of crossing Lake Erie. We observed additional patterns of movement between species, with Zonotrichia albicollis (White-throated Sparrow) and Catharus ustulatus (Swainson’s Thrush) showing a predominately northern movement that increased their frequency of crossing, while Leiothlypis peregrina (Tennessee Warbler) and Setophaga magnolia (Magnolia Warbler) exhibited a northeasterly movement that navigated them away from the shoreline. The observed differences indicate uneven risk of collision with offshore wind experienced by different populations of migratory birds, highlighting the need to identify spatial patterns to inform siting of new wind energy installations and mitigate collision risk.