ABSTRACT
Abstract. We reviewed reproductive life histories and associated nutritional requirements of egg production and incubation for 18 species and subspecies of sea ducks that breed in North America. We also refer to life histories of some European subspecies. We found that basic information for several species remains unavailable for egg composition, egg-laying rates, follicular growth rates and estimates of incubation constancy. Relationships among various life-history traits associated with egg production and incubation by sea ducks revealed that phylogeny and body mass both affect daily and total energetic costs. For example, regression of some lifehistory traits associated with egg production that were related to body mass across all species or subspecies under consideration showed different patterns when compared between Somatereae (eiders) and Mergeae (non-eiders). Also missing for most species were estimates of the proportion of egg nutrients supplied by endogenous stores. Inferences about nutrient
supply to eggs were highly variable, regardless of whether estimation relied on analysis of stable isotopes or the regression of cumulative nutrient production on somatic nutrient reserves. The proportion of egg nutrient supplied by endogenous reserves showed no clear pattern, judging from the lack of relationship to other life history traits. There is a general lack of understanding of whether endogenous nutrient reserves used in reproduction are acquired by sea ducks from wintering habitat, distant staging or those areas proximal to nesting sites. The geographic sourcing of nutrients used in sea duck reproduction should receive additional study because such areas may inuence population-level recruitment. Reported incubation constancy in sea ducks ranged from 81% to 99%, and reected the range of strategies to source nutrients for reproduction. Based on differences in body mass before and after incubation, we estimated that between 8% and 94% of energy requirements during incubation by
different species or subspecies were met with endogenous reserves. The gradient in reliance on endogenous nutrients during incubation across species was a strong function of body mass (r2 = 0.84). We also discuss the potential interplay of contaminants, nutrition and reproduction, and suggest that determination of
nutrient reserve thresholds for breeding are an important research goal.
