KOOPMAN K (1992) Biometrics, weight change and primary moult of an inland population of the Oystercatcher Haematopus ostralegus. LIMOSA 65 (3): 103-108.

This paper deals with the biometrics, primary moult and changes in body weight of inland breeding Oystercatchers in the provinces of Friesland and Groningen (The Netherlands). Females have a longer wing, bill, head + bill and tarsus + toe than males, but the bill is less high (Table 1). The length of the bill varies during the season (mean variation 1.92 ? 1.63 mm), due to differences between rates of growth and abrasion (Fig. I). The primary moult of the Oystercatchers starts on the breeding grounds in early July. Moulting birds loose primaries 1-3 simultaneously or in succession during a short period (Table 2). Coastal birds moult earlier than inland Oystercathers. Among inland birds, females moult earlier than males (Fig. 2). The body weight of breeding females is higher than that of non-breeding females, but there is no difference in weight of breeding and nonbreeding males (Fig. 3). It is suggested that inland birds face a decrease of the food supply in the course of summer as a result of emergence of leatherjackets and of gradually increasing inaccessibility of earthworms. Therefore, inland breeding Oystercatchers depart from their breeding areas as early as possible, viz., when young are independent, in order to moult and fatten up in the Waddensea. Eurasian Oystercatcher Haematopus ostralegus

[free pdf] [dutch summary]