Oyster Predation by the Black Oystercatcher in British Columbia

Abstract

Some authors (Jewett et al. 1953, Guiguet 1955) have claimed that Black Oystercatchers Haematopus bachmani do not, in fact, eat oysters, but there is one recent report of the event (Campbell 1966). Campbell's (1966) description of the technique used by the Black Oystercatcher to open Pacific oysters (Crassostrea gigas) is similar to that described for the European Oystercatcher (H. ostralegus) to open native oysters (Ostrea edulis; Dewar 1922) and that for the American Oystercatcher (H. palliatus) to open Atlantic oysters (C. virginica; Tomkins 1947). This technique involves forcing the bill between the gaping valves of submerged oysters and prying them apart. We observed Black Oystercatchers using a different method of opening Pacific oysters. The purpose of our study was to determine the size of Pacific oysters selected and the method used by the Black Oystercatcher to open them.