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.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.102971 |
| Date | January 2006 |
| Creators | Donehower, Christina E. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Natural Resource Sciences.) |
| Rights | © Christina E. Donehower, 2006 |
| Relation | alephsysno: 002615247, proquestno: AAINR32172, Theses scanned by UMI/ProQuest. |
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