The Ecology of Morecambe Bay. III. The Food and Feeding Habits of Knot (Calidris canutus L.) in Morecambe Bay

Why knot Calidris canutus take medium-sized Macoma balthica when six prey species are available

“…5A), this is presumably the largest prey that is normally ingested. The same upper size limit was also found by Prater (1972), GossCustard et al (1977b), Nehls (1992) and Piersma (pers. comm.).…”

“…The average searching time per prey captured, whether ingested or not, was 43 S, which means that on average, 1.6 probes were made per second of searching. Why did knot ignore Peringia ulvae, which occurred at such a high density, while in other areas and at other times of the year this prey is the only food taken (Ehlert 1964, Lange 1968, Hofmann & Hoerschelmann 1969, Goss-Custard 1970, Prater 1972, Piersma 1989, unpubl., Nehls 1992 , Fig 3 in present study)? Why did knot refuse small Cerastoderma edule, even though -,.…”

“…Oystercatchers take the larger bivalves, which they open by stabbing or forcing the bill between the valves, or by hammering a hole in the shell (Hulscher 1976, 1982, Goss-Custard & Durell 1988, Cayford & Goss-Custard 1990. In contrast, knot swallow bivalves and snails whole (Ehlert 1964, Davidson 1971, Prater 1972, Goss-Custard et al 1977b). …”

Diet of the DunlinCalidris alpinain the Severn Estuary

“…The minimum thickness of the ridge of the shell closest to the hinge is correlated with the total shell height (cf. Prater 1972, who used shell length rather than height), so that the thickness of these ridge pieces was used to determine the sizes of the individuals swallowed by the birds.…”

Reconstructing diet composition on the basis of faeces in a mollusc-eating wader, the KnotCalidris canutus

“…[8][9][10][11][12][13] Although the prey organisms of Knots are sometimes too small to be observed when ingested, 14 hard-shelled molluscs usually dominate their diet. Such molluscs are ingested whole, their crushed remains ending up in droppings and regurgitates.…”