• Behavioral responses of Herring Gulls, Larus argentatus, to lobster fishing in the eastern Gulf of Maine

    by: Yoko Bowen

    Lobster fishing is an iconic element of communities in Downeast Maine. Lobster traps are typically baited with herring, Clupea harengus, which is discarded when traps are pulled. Some lobstermen toss bait immediately overboard, while others bucket the bait for later disposal. Prior studies show that a significant portion of food fed to young gulls in Maine consists of lobster bait discards. During the summer of 2008, I observed gulls responding to lobster boats fishing in the vicinity of Great Duck Island, an off-shore island in the western Gulf of Maine. Over the course of 6 weeks I was able to observe gull behavior around 30 boats, with repeat observations of vessels concentrating their activity in the immediate vicinity of the island. I also analyzed 20 samples of food boli regurgitated by young gulls during banding procedures. Flock sizes around boats were recorded for fishing vessel behaviors that included rapid transit, slow, stop, turn, hauling trap, trap up, toss lobster and bait over. Gull numbers in the vicinity of lobster boats increased in apparent response to visual cues from gulls already over boats and also to lobster boat activity. Peak numbers of gulls (Max = 57) were observed over boats that were actively tossing bait. Some gulls persisted in following boats that were not throwing bait, although flock size never exceeded 12. Eight out of 20 sample food boli contained lobster bait. Bait was found in samples collected on both clear and extremely foggy days, suggesting that gulls may also use aural cues to locate fishing vessels.

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  • Burrow Distribution and Habitat Parameters in Leach’s Storm Petrel

    by: Anna Caroline Perry
    Leach's Storm Petrel

    Historically, efforts to estimate nesting populations of Leach’s Storm Petrel (Oceanodroma leucorhoa) have produced variable results. On Great Duck Island (GDI), census numbers for this species have ranged from 800 to 16,000 breeding pairs (Ambagis 2002). In the most recent census for GDI, Ambagis (2002) calculated that the island supports 9,300 + 6,500 pairs. The high degree of variation in these population estimates may reflect the patchy distribution of this species’ inconspicuous nesting sites, or burrows. To increase the accuracy of future census efforts on GDI, this study sought to refine a model that would account for the distribution of petrel burrows on the island.

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  • Colony collapse in Herring and Great Black-backed Gulls: an assessment of possible causes and consequences.

    by: John Anderson
    Great Duck Island, home to COA's Alice Eno Field Research Station.

    Islands in the Gulf of Maine currently provide nesting sites to as much as 50% of seabirds nesting in the contiguous United States east of the Mississippi. Species include Herring and Black-backed Gulls, Black Guillemots, Double-crested and Great Cormorants, several species of terns, and Leach’s Storm Petrels. Herring and Black-backed Gull (Larus argentatus and L. marinus) populations in parts of the northeastern United States have declined significantly over the past quarter century. Aerial surveys conducted by the U.S. Fish and Wildlife Service in Maine in 1995-6 and 2008 suggest that this decline is non-uniform, with some colonies increasing while others decrease or are eliminated entirely. In general a pattern of near-shore losses is only partially compensated for by off-shore increases. Boat and nest counts of 8 colonies in mid-coast Maine indicate that this trend is continuing. Colonies recorded as healthy or even increasing in 2008 had been abandoned by 2012, or showed few or no fledglings. In some cases colonies that had persisted for decades were completely abandoned during the course of a single season, while others declined more gradually.

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  • Great Black Back Gull Predation on Common Eider Ducklings on Great Duck Island, Maine, USA

    by: Mikus Abolins-Abols

    The increasing number of Great Black-Back Gulls (Larus marinus) in the North-eastern United States has led to concern about their impact on other species of seabirds. Great Black-Back Gulls are more aggressive predators than the more common Herring Gulls (Larus argentatus), and there is particular concern about their impact on Common Eider (Somateria mollissima) ducklings. Great Duck Island supports a mixed colony of Herring Gulls (1200 nests), Great Black-Back Gulls (55 nests) and Common Eiders (19 nests). In addition, the island serves as a nursery for Eider crèches from nearby Little Duck Island. Most of the research was focused on a single Common Eider nursery in the southern intertidal zone of Great Duck Island that adjoins a major gull colony.

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  • Living on the Edge: Gulls and Humans in Off-shore Colonies

    by: Lindsey Nielsen and Annie Hart

    This presentation looks at the effects on nesting gull behavior that results from increased interaction between nesting birds and people. The study sites are Mount Desert Rock (MDR) and Great Duck Island (GDI). We find that flush distance increases with distance to nearest neighbor and that Gulls on GDI flush earlier when approached than Gulls on MDR.

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  • Micro and Macro-habitat selection in breeding Leach’s Storm Petrels

    by: John Anderson

    Leach’s Storm Petrel Oceanodroma leucorhoa is an abundant pelagic seabird that nests in large colonies on islands in the northern hemisphere. Due to the species’ habit of nesting in extensive burrow cavities and of only returning to breeding colonies after dark, precise estimates of population sizes or trends are virtually impossible. Increased development pressure on islands at mid-latitudes raises questions about habitat loss and conservation. Rapid assessment of possible breeding islands and/or key habitats within islands will enhance conservation acquisition strategies. Detailed information on environmental conditions within breeding habitat is of particular value if it can be related to broader and more easily assessed indicators of macro-habitat quality. During the summers of 2003-2006 environmental variables including temperature and humidity within and immediately adjacent to petrel burrows were recorded at 15-30 minute intervals over the course of the breeding season, using a variety of electronic tools including wireless sensor motes and commercially available ‘i-buttons”. These data were transferred to a GIS that allowed us to construct detailed thermal topographies of nesting areas that could in turn be overlaid with vegetation map layers. The use of wireless technology and stand-alone recording sensors allowed us to collect a large (over 500,000 readings from 164 sensors in 2003, over 240,000 readings from 104 i-buttons so far in 2006) sample of environmental data with limited human disturbance to nesting birds. Results show both a higher degree of micro-environmental variability with macro-habitat classifications than expected and a remarkably stable environment within actual nesting cavities regardless of macro-habitat classification. This latter result is particularly significant given the long period of chick development in the burrow system exhibited by this species.

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  • Nest Habitat Overlap Between Large Gulls (Larus sp.) and Black Guillemots (Cepphus grylle)

    by: Adrianna Beaudette and Clare Anderson

    Large gulls such as the Herring Gull (Larus argentatus) and the Greater Black Backed Gull (Larus marinus) have long been considered negative influences on alcids, including the Black Guillemot (Cepphus grylle). Great Duck Island—a seabird nesting island off the coast of Maine—not only provides nesting sites to approximately 50 pairs of Black Backed Gulls and 1200 pairs of Herring Gulls, but also to an estimated 400 pairs of Black Guillemots. Our study compares the nest locations of gulls and guillemots on the island, in order to determine whether the presence of gulls affects the nesting distribution of the Black Guillemot.

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  • Predation on Common Eider Ducklings on Great Duck Island

    by: Sarah E.A. Spruce
    Whale watching takes time.

    Since the 1920s, Great Black-Backed Gulls have increased in frequency in the Gulf of Maine, raising concerns over possible effects on Common Eider populations from over-predation.

    In order to assess whether predation rates on ducklings by Great Black-Backed Gulls are affected by human disturbances, particularly researcher created disturbance, we observed a Common Eider nursery from a vantage point that nullified observer effects.

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  • Preferential Utilization of Rocky Coastline Habitat by Herring Gulls

    by: Aspen Reese
    Herring Gull on rocky habitat

    The Herring Gull (Larus argentatus) has an extensive Holarctic distribution encompassing many habitat types. In order to isolate possible factors contributing to nesting site selection, this study analyzed the effects of territoriality concerns, presence of nesting Great Blackbacked Gulls, and chick survivorship as a function of habitat choice.

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  • The Impact of Bald Eagle Predation on Herring Gull Survivorship in Maine, USA

    by: Katherine Shlepr

    Local Herring Gull (Larus argentatus) populations in Maine declined over 60% between 1996 and 2008, with several in-shore nesting colonies being completely abandoned (Anonymous 2008). In the same time period, Maine’s Bald Eagle (Haliaeetus leucocephalus) population more than doubled to 450 breeding pairs which concentrate along the coast (Todd and Meehan 2010). Bald eagles living on the coast rely primarily on seabirds for food, and take advantage of the chicks of these other species for easy prey (Todd et al. 1982, Anonymous 2008). I assessed the role of Bald Eagle presence and predation in the decline of Herring Gull colonies throughout mid-coast Maine, using one island in particular to observe eagle and gull behavior.

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  • Tracking Derelict Fishing Gear: A Buoy Island Map

    by: Robin Owings
    Derelict fishing gear on Great Duck Island

    An ongoing study of drift patterns of lobster buoys and other marine flotsam in order to determine the distribution and origin of marine debris in the Acadia region. During the summer of 2011, 1517 buoys were photographed and documented on Great Duck Island (GDI). These buoys have subsequently been mapped based on likely points of origin according to ownership patterns.

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  • Use of GPS Tags in Evaluating the Impact of Oyster Farms on Gull Foraging Patterns

    by: John Anderson and Katherine R. Shlepr

    The rapid decline of traditional fin-fisheries in the Gulf of Maine and elsewhere has led to an increasing emphasis on concentrated aquaculture operations, especially in inshore environments including protected bays and coves. This in turn has raised concerns about the possible attraction of gulls and other seabirds to production sites in the vicinity of airports or other sensitive humanized landscapes. In addition, the increasing tendency for once “working waterfronts” to be transformed into summer houses and second homes creates tensions between “locals” and “people from away” both of whom may share a common love for the coast, but may have very different ideas of appropriate uses.

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  • Using Pellet Collection and Chick Regurgitation to Determine the Diet of Herring Gulls (Larus smithsonianus) on Great Duck Island

    by: Caroline Brown
    Great Duck Island, home to COA's Alice Eno Field Research Station.

    Great Duck Island is a nesting seabird island located in the Gulf of Maine occupied by over 1200 pairs of gulls. Its proximity to the mainland, 12 km offshore, provides ample opportunity for Herring gulls (Larus smithsonianus) to feed themselves and their offspring in intertidal and freshwater habitats. Its location is also close to several nearby fisheries, including those for lobster and tuna. During June and July 2016, I collected regurgitate samples from adults and juveniles and prey remains around nests during the prefledging and fledging period. Regurgitation
    samples were collected during handling of chicks for growth and banding studies. I used a protocol developed on the isles of Shoals (2016) which included five categories of prey for the Herring gulls of Great Duck Island, and examined the remains in greater detail.

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