Seasonal and diel patterns of fall waterbird migration along New Jersey’s Atlantic coast.

Presenter/Co-author: David Mizrahi / David La Puma and Tom Reed (NJ Audubon’s Cape May Bird Observatory, New Jersey)

The mid-Atlantic region is a major thoroughfare for a wide variety of waterbird species during southbound migration. Systematic migration monitoring provides insights into behavior (e.g., seasonal and diel movement patterns, responses to weather) and population trajectories, and can be a valuable tool for threat assessment (e.g., effects of wind power development). Here we provide a summary of waterbird migration data collected by New Jersey Audubon’s Cape May Bird Observatory along southern New Jersey’s Atlantic coast since 1995. Daily counts were conducted between 22 September and 15 December, from sunrise to sunset at a fixed location near the mouth of Townshend’s Inlet, Avalon, Cape May County. To date, we observed nearly 100 waterbird species totally more than 19,000,000 individuals. Five species, Red-throated Loon (Gavia stellata), Northern Gannet (Morus bassanus), Double-crested Cormorant (Phalacrocorax auritus), Surf Scoter (Melanitta perspicillata), and Black Scoter (M. nigra) comprised 84% of all individuals observed. Approximately 50% (median passage) of all birds pass by 30
October. This appears driven primarily by Black and Surf Scoter movements, which comprise 45% of the total flight. In this paper, we will provide additional insight into the seasonal and diel patterns of migration for the five most commonly observed species and discuss differences in their migration behavior.