Feeding Ecology of Knots at Schiermonnikoog during Autumn 1990: Deep 'Macoma'Force Knots' Foraging Effort to Great Heights

摘要

Knots of the subspecies Calidris canutus islandica were studied while staging onthe intertidal mudflats near Schiermonnikoog in the autumn of 1990. The question of the survey was whether Knots of the subspecies C. c. islandica wintering in the eastern part of the Dutch Wadden Sea are influenced in their foraging behavior or even occurrence by the seasonally induced burying depth of their main prey Macoma balthica in the course of autumn. Do they have problems keeping a balance between energy intake (food) and expenditure (thermoregulation, activity) as a result of the deeper burying depth of Macoma balthica. Budgets and energy intake were determined. Moreover, prey sampling (both depth and density) took place at those places where Knots had been seen foraging. In this way food availability was estimated.