|Intra- and inter-specific interactions of foraging American oystercatchers on an oyster bed|
Tuckwell, J.; Nol, E. (1997). Intra- and inter-specific interactions of foraging American oystercatchers on an oyster bed. Can. J. Zool. 75(2): 182-187
In: Canadian Journal of Zoology = Revue canadienne de zoologie. National Research Council: Ottawa. ISSN 0008-4301, more
Abundance; Aquatic birds; Food preferences; Foraging behaviour; Interspecific interactions; Intraspecific relationships; Marine birds; Marine molluscs; Oyster beds; Parasitism; Predation; Crassostrea virginica (Gmelin, 1791) [WoRMS]; Geukensia demissa (Dillwyn, 1817) [WoRMS]; Haematopus ostralegus Linnaeus, 1758 [WoRMS]; Larus argentatus Pontoppidan, 1763 [WoRMS]; Larus marinus Linnaeus, 1758 [WoRMS]; Mytilus edulis Linnaeus, 1758 [WoRMS]; Marine
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We compared the rates of intraspecific and interspecific kleptoparasitism of foraging American oystercatchers (Haematopus palliatus) on a commercial oyster () bed during two seasons and between 1979 and 1995. In 1979 most conspecific kleptoparasites were immature oystercatchers and victims were adults. Both intra- and inter-specific parasitism were more common in 1979 than in 1994 or 1995. Kleptoparasitism by conspecifics was more common than by gulls (Larus argentatus, L. marinus) but was not density dependent, Gulls primarily kleptoparasitized oystercatchers foraging on mussels (Geukensia demissa), with their longer handling times. Kleptoparasitism by gulls increased as the number of gulls on the oyster bed increased, and the presence of gulls significantly depressed intake rates and sizes of mussels taken by oystercatchers during autumn. Oystercatchers ate smaller oysters in autumn than in winter in both the presence and absence of gulls. The presence of conspecific and gull kleptoparasites changed the oystercatchers' relative preference for oysters over mussels in their diet. The presence of gulls only partly explained the oystercatchers' lower rates of intake of oysters in autumn than in winter.