Prey Dynamics and the Breeding Phenology of Common Terns (Sterna hirundo)

We examined fish dynamics within the temporal framework of the reproductive cycle of Common Terns from 1982-1985. The hypothesis that the breeding season of terns is timed to overlap with a seasonal increase in food abundance was supported by the data. Prey fish were more available during breeding than postfledging. However, the further hypothesis that the timing of tern breeding is adapted to exploit peak prey availability while feeding growing chicks was not generally supported over the course of the study. Food for terns peaked and began to decline before the period of peak demand of food by chicks.