The large population of breeding Herring Gulls and Great Black-backed Gulls on South Monomoy Island, Cape Cod, Massachusetts has been thought to negatively affect the breeding success of the threatened Piping Plover. Following the Piping Plover Recovery Plan s call for gull colonies to be removed from Piping Plover breeding sites, in 1996, the USFWS conducted gull removal on part of South Monomoy Island. We determined relative gull abundance on South Monomoy Island from 1998-2000 by counting gulls within 100-m radius plots located on the shoreline. We quantified Piping Plover behavior and habitat use by conducting instantaneous and 5-minute behavioral observations. We quantified characteristics of Piping Plover nesting habitat by measuring characteristics along random transects. We measured gull abundance, beach width, and prey abundance, and then used logistic regression to determine what habitat characteristics influenced Piping Plover nesting area selection. We monitored Piping Plover reproductive success and population fluctuations on South Monomoy Island. Gull abundance in the gull-removal area was lower than gull abundance in the reference area throughout the Piping Plover breeding season. The difference in gull abundance between the areas did not affect Piping Plover behavior, nest success, chick survival, or productivity. We found that gull removal did not result in an increased Piping Plover population on the island. In both management areas, prenesting plovers preferred to forage in moist substrate habitats. Wide backshore and open vegetation habitats characterized nesting areas. Broods spent most of their time foraging and preferred moist substrate habitats when available. Plovers were not prevented from occupying more suitable habitat by large gulls. Fewer large gulls were observed near prenesting plovers, plover nests, and plover broods than near random plots. Fewer large gulls were observed in plover nesting areas than in unused areas when the nesting areas were defined by all area within 100-m or 500-m of a plover nest. We argue that this apparent spatial separation between Piping Plovers and large gulls is due to different habitat preferences among the species. We found that gull removal on South Monomoy Island did not result in increased Piping Plover reproductive success, and large gulls did not affect breeding Piping Plovers on South Monomoy Island from 1998-2000. / Master of Science

In recent years, gull control has become closely tied to seabird restoration in the Gulf of Maine. Herring (Larus argentatus ) and Great Black-backed (L. marinus) gulls are the principal targets of control, yet anecdotal reports suggest that gull predation remains an important source of egg and chick mortality at many managed seabird colonies. The main objective of this study was to examine the impact of gull predation on the reproductive success of several waterbird species nesting at restoration sites in Maine. Particular emphasis was placed on understanding gull foraging behavior, identifying foraging constraints, and applying this knowledge to management of gulls and small seabirds. / Productivity of Common (Sterna hirundo), Arctic ( S. paradisaea), and Roseate (S. dougallii) terns was monitored and daily predation watches were conducted at Eastern Egg Rock, Maine from 2003-2005. In 2004 and 2005 only, attempts were made to shoot gulls preying on terns. Shooting failed to eliminate predation, and tern predation risk was influenced by nest location, but not year. Common and Arctic terns experienced heavy predation in all years, but Roseate Tern nests were seldom depredated, presumably because Roseates selected nest-sites with more cover. Great Black-backed Gull predation was influenced by visibility, tidal state, and year, while Herring Gull predation depended only on the stage of the tern breeding cycle. There was little evidence that gulls preyed selectively on unfit chicks. The limitations of shooting are discussed and non-lethal alternatives suggested. / Common Eider (Somateria mollissima dresseri) nest (hatching) success, habitat use, and duckling survival were studied at Stratton Island, Maine in 2004-2005. Eiders nested in a variety of habitats offering vegetative cover and enjoyed high nest success. Duckling survival was negligible however, because of opportunistic, group attacks by Great Black-backed Gulls. Glossy Ibis (Plegadis falcinellus) also appeared to suffer heavy gull predation, with adults occasionally attacked in flight. In 2006, gull displacement walks, gull nest/egg destruction, and occasional shooting were used on a trial basis and may enhance future eider production.

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