Delineating Breeding Populations and Tracking Night-time Movements of Long-tailed Ducks Wintering in Nantucket Sound

Massachusetts Audubon Society staff in partnership with U.S. Geological Survey staff will radio tag 25 Long-tailed Ducks (LTDUs) in order to gather information on nighttime roosting locations for this species, especially with respect to Horseshoe Shoal, the proposed site of a 130-turbine wind farm.  Hundreds of thousands of LTDUs overwinter in Nantucket Sound.  Each day at dawn, these ducks exit the Sound traveling to feeding sites, returning to the Sound at dusk.  Massachusetts Audubon Society and the applicant for the Cape Wind project have conducted extensive aerial surveys of Nantucket during daylight hours when the vast majority of LTDUs are absent from the Sound.  We have, therefore, no information on the nighttime roosting locations of this species.  In particular, we need to know whether Horseshoe Shoal is used by significant numbers of LTDUs as a nighttime roosting site or staging area as they exit or return to Nantucket Sound.  If the answer to this question is yes, then the LTDUs are potentially at risk to collision with the wind turbines when they enter, exit, or otherwise move within the project area.

Twenty-five LTDUs will be captured from a high-speed boat and will be implanted with VHF radio transmitters.  Aerial tracking of radio-tagged ducks will occur between February 1 and mid-April.  Each tagged bird will be relocated from the air approximately ten times.  In addition, five LTDUs will be instrumented with satellite transmitters.  Maps of individual birds from each flight will be created from GPS points using the plane’s onboard GPS system and dLog software.  Trial boat trips will be used to test different methods of assessing abundance and dispersion of LTDUs in association with tagged birds or Horseshoe Shoal.  Results will be used to address several questions regarding nighttime use of the Sound by LTDUs.  Specifically, do individual LTDUs roost in the same general area of Nantucket Sound or do they range widely within the Sound over time?  Other questions or hypotheses regarding LTDU nighttime distribution on Nantucket Sound will depend on the nature of the data collected, but should provide important information that currently does not exist.

Contact Matthew C. Perry, Taber D. Allison, or Simon Perkins for more information.

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