Mysterious attendance cycles in Cory’s shearwater, Calonectris diomedea: An exploration of patterns and hypotheses

摘要: Several species of seabirds show cyclic patterns attendance at their nesting colonies. We examined the variation in numbers Cory's shearwater three colonies (two oceanic and one located on continental shelf), including world's largest, Selvagem Grande, Madeira, Portugal considered several hypotheses concerning causal mechanisms. At cycles were exceptionally marked regular, with a periodicity ranging from 7.8 to 11 days, involved both breeders nonbreeders. In contrast, was aperiodic nearby much smaller colony (Selvagem Pequena), also off Portuguese coast (Berlenga Island). found no relationships between number birds ashore environmental variables such as wind direction speed or lunar cycle. Cycles did not seem be driven by oscillations food availability accessibility, given that they correlate daily chick growth rates (which acyclic) diet. Despite regularity, slightly out phase different sectors which suggests social interactions could act an entrainment agent for endogenous rhythm, so are probably more likely occur large dense Observations consistent hypothesis facilitate maximizing probability encounters colony. However, exact mechanisms through these remarkable controlled still completely unknown, clearly further research is needed.