Effects of parental quality and egg size on growth and survival of herring gull chicks
T. S. Risch and F. C. Rohwer
Environmental Laboratory, Center for Environmental and Estuarine Studies,
Abstract: We performed a clutch-transfer experiment with herring gulls (Larus argentatus) to quantify how parental attributes and egg size affect chick growth and survival. The quality of parents was assessed by their average egg mass. There was no association between hatching success and egg mass in either unmanipulated or experimental nests. Among experimental treatments, the high-quality parents had a significantly higher chick survival rate than low-quality parents in 1991 and when data from 1990 and 1991 were pooled. A positive effect of egg size on chick survival was apparent only when data from both years were pooled. Chicks raised by high-quality parents had higher structural growth rates (tarsus) than chicks raised by low-quality parents. We discount the likelihood for selection of larger eggs because egg size has trade-offs with other life-history traits that have a strong influence on fitness. Despite the correlation between parental quality and chick survival, we doubt that there is character displacement for greater parental quality. Parental quality is probably affected by nutrition and is expected to have low heritability.
SREL Reprint #2460
Risch, T. S. and F. C. Rohwer. 2000. Effects of parental quality and egg size on growth and survival of herring gull chicks. Canadian Journal of Zoology 78:967-973.