Factors Determining the Number and Size of Eggs Laid by the Herring Gull

Publisher Website
Google Scholar
Abstract
The herring gull (Larus argentatus) can compensate for the early loss of its 1st-laid egg by laying an additional egg, so that the normal clutch size of 3 eggs is incubated. It is not a determinate layer and some individuals are capable of the protracted laying of a series of eggs. The presence of the 1st-laid egg stimulates the onset of incubation and the cessation of laying beyond the normal clutch size. Broodiness appears to result in a significant reduction in the amount of albumen rather than yolk laid down in the 3rd and last-laid egg. This egg is significantly smaller than the first 2 under normal laying conditions, but is not so small when the onset of incubation is delayed by the early loss of the 1st egg. Smallness of the 3rd egg reduces its incubation period and the degree of asynchrony at hatching. Although there is considerable variability in the number and size of eggs laid by herring gulls, the last eggs and yolks laid during protracted laying were similar in size. While normal clutch size is 3 eggs, it appears that a minimal egg size limits the clutch to .ltoreq. 2 in some individuals. This may be an adaptation to prevent the laying of small eggs with little chance of producing fledged young.