Territory Type in Relation to Onset of Breeding in the Herring Gull (Larus argentatus): Does the Early Bird Get the Worm?

Abstract

The structure of a Herring Gull (Larus argentatus) colony off Hanko, southwestern-Finland, was studied in 1983-86. Breeders were grouped into early, peak and late layers. Center nests had more neighbors than edge nests. Nearest- and second-nearest neighbor distances were also smaller for center nests in most cases. Center and edge territories were evenly distributed between early, peak and late layers in all years. There was no consistent pattern with respect to number of neighbors, and distances to nearest- and second-nearest neighbors among the laying groups. I suggest that individual pairs are unable to predict their neighbors when at least some asynchrony occurs, and that it may be impossible to optimize territory acquisition by early breeding. The possible mechanism enabling late breeders to obtain center territories is decreasing levels of aggression in earlier breeders already incubating.