A model for the evolution of creching behaviour in gulls

摘要

A creche is an aggregation of chicks outside nesting territories, within chicks continue to be fed only by their own parents. Several adaptive functions of creching have been proposed, the most frequent being a reduction in predator pressure. Using an evolutionary stable strategy approach based on the computation of individuals' fecundity, we examined which regime of aerial and terrestrial predation is likely to favour the evolution and stability of the creching strategy (CS) in gulls. Our results confirm the hypothesis that habitat instability associated with high levels of terrestrial predation favours the evolution and maintenance of creching behaviour. Moreover, our results suggest that a low aggressiveness against predators may be a pre-adaptation to a CS. In contrast, the high synchronisation often observed in creching species does not favour the evolution of a creching behaviour and is thus probably under selection pressures different from those modelled here.