Master of Science, The Ohio State University, 2017, Environment and Natural Resources

Each spring and fall, hundreds of species of North American birds migrate between breeding and wintering grounds. Many migrant songbirds are in steep decline, and understanding the movement behavior and habitat use of these birds during migration is crucial to developing effective conservation action. One of the most rapidly declining songbirds in North America is the Rusty Blackbird, which has declined more than 85% over the last 50 years. Very little is known about their behavior and habitat requirements during migration, so we studied the species during spring and fall migration at a high-traffic stopover (refueling) site in northern Ohio. We utilized an automated telemetry array in the western Lake Erie basin and across Ontario to track landscape-scale movements of radio-tagged birds during and after migratory stopover events. We found that stopover duration of Rusty Blackbirds was unusually long for a songbird (25 days), and that nearly all captured birds (98%) were molting body feathers in the spring, which may partly explain the long stopover. Many individuals also made landscape-scale (10-35km) movements during their stopover event. These behaviors describe a migration strategy that closely resembles shorebird migration, where birds congregate to forage for several weeks at key staging areas. This indicates that high-quality staging habitat may be critically important to Rusty Blackbird populations. In addition to movement behavior, we investigated their fine-scale habitat preferences on stopover. We found that Rusty Blackbirds selected microhabitat with shallow water and leaf litter, often avoiding dense herbaceous cover. They also preferred areas close to habitat edges with some canopy cover, and with a mixture of habitat types. Our description of Rusty Blackbird stopover habitat use and behavior will help inform conservation and management practices across the species' migratory range.

Committee: Christopher Tonra PhD (Advisor) Subjects: Wildlife Conservation