Breeding dispersal of Northern Flickers Colaptes auratus in relation to natural nest predation and experimentally increased perception of predation risk

摘要

After nest predation, breeding dispersal can be an effective strategy to avoid local nest predators. Furthermore, encounters with predators at a nest during the pre-laying stage may be used by parents to judge future risk, such that they may abandon a nest when a nest predator has been encountered. We studied whether the between- and within-year breeding dispersal of Northern Flickers Colaptes auratus was dependent upon the outcome of the previous nesting attempt. We also tested whether pairs presented with a model predator prior to egg-laying were more likely to abandon their nests than were pairs presented with a control model. Between years, males moved significantly further after having their nest depredated than did successful males, and females showed the same trend. However, these movements did not result in greater reproductive success. More pairs switched sites within years after having their nest depredated, but those that remained and those that moved had equal subsequent nest success. Stressful encounters with predators involving nest defence may trigger dispersal both between and within years, although reproductive benefits are unclear. The proportion of pairs abandoning nests did not differ between parents presented with control or predator models, suggesting that a single encounter with a predator is not a sufficient deterrent against continued use of a particular nest.