Conspecific nest parasitism is associated with inequality in nest predation risk in the common goldeneye (Bucephala clangula)

Abstract

Previous studies of the role of nest predation in conspecific nest parasitism have not taken into account the possibility that predation risk may not be randomly distributed among nest sites and that breeding individuals may use different cues to assess the risk and adjust their reproductive tactic between years accordingly. Especially in cavity-nesting species, the role of nest predation in conspecific nest parasitism has been downplayed, while the role of nest site limitation has been highlighted. Using both observational and experimental data, I show that in the common goldeneye (Bucephala clangula), a cavity-nesting species in which conspecific nest parasitism is common, predation risk varies considerably between nest sites and does not follow a random expectation. The inequality in predation risk between nest sites also showed up in the occurrence of parasitized nests in an experimental setup. Nests parasitized in year t were more frequent in those nest sites that were not depredated during the previous nesting attempt in year t - n than in nest sites that were depredated and in control nest sites that had not been used for nesting before. A nest site addition experiment revealed that conspecific nest parasitism was not associated with nest site limitation. My findings give support for the hypothesis that nest predation is an important ecological factor explaining conspecific nest parasitism in goldeneyes.