DEVELOPING METHODS TO MONITOR SEABIRD RESPONSE TO DISTURBANCE ON A COASTAL MAINE ISLAND

DEVELOPING METHODS TO MONITOR SEABIRD RESPONSE TO DISTURBANCE ON A COASTAL MAINE ISLAND

By Monika Parsons

Thesis Co-Advisors: Dr. Cynthia Loftin and Dr. Frederick Servello

An Abstract of the Thesis Presented

in Partial Fulfillment of the Requirements for the

Degree of Master of Science

(in Wildlife Ecology)

May, 2011

Understanding responses of breeding seabirds to the introduction of new source of disturbance is important for effectively managing breeding colonies. In Maine, coastal areas where birds nest are subject to a variety of potential disturbances including the establishment of new aquaculture facilities.  I examined activity of four seabird species nesting on Jordan’s Delight Island, Washington County, Maine: common eiders (Somateria mollissima), black guillemots (Cepphus grylle), great black-backed gulls (Larus marinus) and herring gulls (Larus argentatus).

During May-August 2008 and 2009 I positioned five time-lapse cameras recording one image per minute facing the water to record boat activity. Researchers recorded their own activity and spent 180 hours in 2008 and 310 hours in 2009 observing for avian predators. Incubation constancy of common eiders, herring gulls and great black-backed gulls was monitored by recording nest temperature with loggers installed in nests. Colony attendance was measured with time-lapse cameras overlooking four gull nesting areas and two guillemot nesting areas.

Eiders recessed longer in 2008 than 2009 and more often during daylight hours in both years. Multiple incubating eiders simultaneously left their nests in response to researcher activity on the bluffs above the eider nesting area on two of four occasions and these recesses were longer (61 min) than recesses in the absence of disturbance (34 min). Eiders did not simultaneously leave their nests in response to other monitored disturbances.

 Herring and great black-backed gulls were indistinguishable from one another in time-lapse images and therefore were pooled.  Gulls exhibited a flight response to eagles and humans but not to ravens and boats.  Incubating gulls left their nests for 2-3 minutes when an eagle flew directly overhead.  Colony attendance did not change in response to disturbances other than human activity.

Raven presence was the most frequent and longest duration disturbance to guillemots, preventing them from visiting nesting areas for up to four hours at a time. Boats occasionally elicited responses from guillemots; however, it was not clear why guillemot response to boats was inconsistent.

            These methods will inform studies intended to document behavior of these species before and after aquaculture facility construction.