THE RELATIONSHIP BETWEEN EGG SIZE AND POSTHATCHING DEVELOPMENT IN THE THICK-BILLED MURRE

Abstract

Many nonexperimental studies have reported positive relationships between egg size and posthatching survival or growth in birds. However, these results might be confounded by underlying correlations between egg size and parental attributes. At Coats Island (Northwest Territories, Canada), in 1994 and 1995, we examined the effects of egg size and parental quality on posthatching growth in mass and wing length in the Thick-billed Murre, a colonial, cliff-nesting, Arctic seabird in which the single chick leaves the nest at a young age and at a preliminary stage of development. The relationship between egg size and parental quality was randomized by switching eggs among pairs. The size of the egg originally laid by the experimental females was used as a putative measure of their quality. The size of the egg from which the fostered chicks hatched had little effect on the rate at which they gained mass. Conversely, the rate of wing growth increased with egg size, the main difference occurring at 6–10 d of age, ...