Great Lakes avian radar technical report Huron and Oceana Counties, Michigan

Global wind patterns help to move millions of migrating birds and bats through the Great Lakes region, where shorelines provide important stopover habitat. Shorelines are thought to concentrate migrants, as they offer a last refuge near a geographic barrier and are, most likely, used for navigation. Shorelines also offer attractive areas for wind energy development. With this potential for conflicting interests, more information is needed on the aeroecology of the Great Lakes shorelines. We used two avian radar systems to monitor migration that occurred along shorelines on opposite sides of Michigan in Oceana and Huron Counties. Our automated systems tracked and recorded target (bird and bat) movements continuously from mid-August to mid-November, 2011. We calculated the direction of movement, target passage rates, and altitude profiles for the air space above our study areas. We also developed a model of our vertical sample volume that allowed us to report an estimate of target density by altitude band. Migration appeared strong along the studied shorelines in Michigan and our results highlight the potential role of radar in implementing the Land-Based Wind Energy Guidelines.