Differential distribution of Oystercatchers Haematopus ostralegus overwintering on the Wash, east England

Abstract

Capsule: Distribution varied with age, sex and feeding method. Aims: To investigate how shorebirds are differentially distributed on their overwintering grounds. Methods: We analysed age and bill measurements of Oystercatchers captured on the Wash in the 1990s. Results: Oystercatchers caught on the southwest shores were more likely to be young birds and females. Birds caught on the east shore were more likely to be adults and males. Shellfish-stabbers were more common on the south and east shores and shellfish-hammerers more common on the west shore. Most mudflat-feeding birds were caught on the south shore. Conclusions: Phenotypic differences mean that juvenile and female Oystercatchers tend to specialize in different diets and feeding methods than adults and males. This results in age and sex differences in distribution. Understanding differences in distribution can be critical when trying to predict the effect of environmental change on a given population.