Habitat-patch occupancy in the common goldeneye (Bucephala clangula) at different stages of the breeding cycle: implications to ecological processes in patchy environments

Abstract

We studied the pattern of habitat-patch occupancy of radio-tagged common goldeneye ( Bucephala clangula (L., 1758)) females in two sequential stages of the breeding season, the nest stage and the brood stage, and whether the resources needed in nesting and brood-rearing are spatially inter-related as revealed by patch occupation rate of goldeneye females in these stages. We also studied patch-specific factors potentially explaining the rate of patch occupation separately during the nest stage and the brood stage. There was no association in patch occupation rate between the nest stage and the brood stage, indicating that all the critical resources needed to complete a successful breeding cycle were not met within the same habitat patch. At the nest stage, patch occupation rate increased with nest-site availability and decreased with nest predation rate but was not affected by vegetation luxuriance or patch size. Vegetation luxuriance had a positive effect on patch occupation rate at the brood stage, whereas nesting success of the focal patch had no effect. Results suggest that nest-site selection and brood-stage habitat selection are governed by different ecological factors. We conclude that breeding-stage-specific resource requirements redistributed individuals among habitat patches across the landscape, implying dynamic distribution of ducks between nesting and brooding stage.