- Parson, Monika
University of Maine Graduate School
Understanding responses of breeding seabirds to the introduction of new sources 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. The response of nearby nesting birds has not been studied in the context of finfish aquaculture in Maine. I examined the effectiveness of methods for remotely monitoring nesting seabird behavior and documenting the behavioral responses of four species of nesting seabirds to disturbance events.
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). Given their widespread nesting distribution, these species are likely to be affected by aquaculture operations established near nesting islands along the Maine coast.
This study was conducted during May-August 2008 and 2009. I positioned five time-lapse cameras (Reconyx, Inc.) facing the water to record boat activity and recording one image per minute. 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; however, multiple eiders did not simultaneously leave their nests in response to other monitored disturbances. Recesses in response to researcher activity on the bluffs were longer (61 min) than recesses in the absence of a researcher (34 min).
Herring and great black-backed gulls were indistinguishable from one another in time-lapse photographs, and therefore their photo data 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. Guillemots also responded to eagles; however, eagle visits were brief (<5 min) and infrequent and did not keep birds off the colony for extended periods. Boats occasionally elicited responses from guillemots; however, it was not clear why guillemot response to boats was inconsistent.
The methods presented herein are effective for monitoring episodic disturbances similar to the boat, avian predator, and human activity recorded on Jordan's Delight, and, combined with the knowledge of bird behavior in response to these disturbances, will inform studies intended to document behavior of these species before and after aquaculture facility construction.