Using Passive Acoustic Monitoring to Determine Temporal Patters and Mixed Species Flocking Associations of Migrating North American Warblers in the Gulf of Maine

Recent development of plans for offshore and land-based wind energy projects has created the need for a better understanding of migration in the Gulf of Maine region, an important flyway for countless migrant birds each year. To better understand migration in this region, the University of Maine’s Lab of Avian Biology, working in collaboration with the U.S. Fish and Wildlife Service, deployed acoustic recording units at various sites throughout the Gulf of Maine to detect and quantify flight calls of nocturnally migrating songbirds. Using these data from selected nights, the detected flight call temporal patterns of American Redstarts (Setophaga ruticilla), Myrtle Warblers (S. coronata coronata), Black-and-white Warblers (Mniotilta varia), Common Yellowthroats (Geothlypis trichas), and Ovenbirds (Seiurus aurocapilla) were shown to be bunched non-uniformly throughout given nights. To show evidence of birds flying in aggregations or flocks a five second window of time was established around each selected warbler’s detected flight calls and the presence of a corresponding flight call within that call window was treated as evidence of a possible flock or aggregation of birds. Approximately 50% of the detected flight calls of all five species showed evidence of potential conspecific and heterospecific flock associations with other songbirds during nocturnal migration.