Migration and Habitat Use by Seabirds in the Atlantic Flyway: Evaluation of Potential Impacts of Proposed Wind Farms

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Overall, this study tracked movements of over 400 individuals of three species over the course of five years; one of the most comprehensive satellite tracking studies of marine birds ever conducted in Atlantic North America. Results provide a better understanding of how diving birds use offshore areas of the mid-Atlantic U.S. and beyond, and, in combination with results from other types of research (e.g., surveys, other tracking work), can be used to inform placement and pre- and post-construction impact assessments of offshore energy infrastructure. Additional work is needed to put the extensive quantity of information collected on birds in the offshore environment into a common analytical framework for undertaking the most informed management decisions.

The Challenge: Demands for alternative energy are increasing and offshore wind projects are slated for several areas used by seabirds in coastal areas of the Atlantic flyway and in the Great Lakes. There is a need to identify the most important habitats for seabirds related to the construction of turbines to evaluate and minimize potential adverse effects on seabirds and their habitats. This will be a large scale, multi-year, collaborative project that will use satellite telemetry to document annual migration patterns and to assess risk to seabirds in specific areas in eastern North America where offshore wind projects are planned. Target species include black scoter, surf scoter, white-winged scoter, long-tailed duck, red throated loons and northern gannets.

The Science: Using surgically implanted satellite transmitters we will fulfill the following objectives: 1) Estimate average length-of-stay during winter in areas of highest concern relative to wind farm developments; 2) Map local movements of individual radio-marked birds in areas slated for placement of wind turbines; 3) Fully describe the annual migration patterns for four species of seaducks: surf scoter, black scoter, white-winged scoter, long-tailed duck and two seabird species: red-throated loon and northern gannet in the Atlantic flyway; 4) Quantify the proportion of the flyway population of each of the species that winters within the Great Lakes, north Atlantic, mid-Atlantic, and south Atlantic regions; 5) Estimate rates of annual site fidelity to wintering areas, breeding areas, and molting areas for all species in the Atlantic flyway. 

The Future: All species used Federal offshore waters substantially more during migratory periods than in winter. Offshore use during migration was particularly extensive for Northern Gannets, with WEAs and Lease Areas overlapping their fall and spring distributions more than the other species. Red-throated Loons and Surf Scoters exhibited more coastal use than Northern Gannets during migration, and WEAs and Lease Areas generally overlapped with their distributions less extensively. The greatest overlap of WEAs and Lease Areas with Red-throated Loon and Surf Scoter distributions occurred during spring migration, and was concentrated in the northern half (MD–NJ) of our study area, and the area immediately to the north (e.g., Cape Cod and Islands), with some additional overlap of Red-throated Loon distribution further south along the North Carolina coast. Red-throated Loons and Surf Scoters often migrated overland in fall resulting in less overlap with WEAs and Lease Areas during this period. Despite the increased use of Federal waters and consequent increased potential for exposure to future offshore wind development in WEAs and Lease Areas during migratory periods, the overall area of overlap and potential exposure generally made up a very small percentage of the overall distributions of our study species during this period (< 5%), and occurred during a brief portion of the annual cycle.