Coastal and offshore counts of migratory sparrows and warblers as revealed by recordings of nocturnal flight calls along the Ohio coast of Lake Erie

Abstract

ABSTRACT The identification of migratory pathways is critical to understanding potential risks affecting migratory birds. The Great Lakes are an important stopover area along the migratory pathway of millions of nocturnally migrating songbirds. However, large expanses of open water can act as a geographic barrier to migrating songbirds resulting in flight “detours” and increased mortality. We recorded nocturnal flight calls (NFCs) of migratory warblers (one species and one species group) and sparrows (three species) at four sites along the Ohio coastline of Lake Erie during two spring migratory seasons. One pair of coastal and offshore sites was located in the central basin, another pair of coastal and offshore sites was located in the western basin with its associated island archipelago connecting Ohio with Ontario. Acoustic monitoring of NFCs suggested that (1) fewer birds were recorded aloft over offshore, open water sites compared to closely associated coastal sites; (2) sparrows apparently were more ...