Relationship between egg size and post-hatching chick mortality in the herring gull (Larus argentatus).

Abstract

IN many gull species, the third laid egg of the typical three egg clutch is distinctly smaller than the first two1,2. In the herring gull (Larus argentatus), the chick hatching from this third egg suffers a much higher mortality than either of its siblings3, although the hatching success is the same for all three eggs. In a series of egg transfer experiments carried out on the Isle of May, Scotland, it has been possible to demonstrate at least two factors contributing to this differential mortality, namely the size disadvantage and the sequence of hatching, because third laid eggs normally hatch last. Although the survival of chicks from third eggs increased when they were the first to hatch, it was still lower than that of its siblings.