ABSTRACT
Key Words: abundance, conservation, densitydependence, life-history traits, population model, vital rates.
Sea ducks differ from other waterfowl, and other birds, in their unique combinations of life-history traits, habitats used, and conservation concerns (Introduction, this volume). Many of these attributes have been highlighted in the preceding chapters of our volume and provide the rst major compilation of ecological data for tribe Mergini. Among waterfowl, sea ducks are a diverse group (Chapter 2, this volume). Eiders and other species have life-history characteristics similar to geese in terms of high survival rates and low levels of fecundity, whereas mergansers are more similar to dabbling ducks with high fecundity and
lower survival (Chapter 3, this volume). Sea ducks have goose-like life histories, but mating systems are similar to other ducks, with females providing all direct parental care. Further, some species of sea ducks are among the best examples of capital breeders where most nutrients and energy for egg laying and incubation come from stored reserves (Korschgen 1977). Other aspects of reproductive behavior, especially pre-and posthatch brood amalgamation (Chapter 11, this volume), and the high proportion of species that are cavity nesters, are unusual and the sea duck tribe has been an important study system for understanding
these phenomena. As highlighted throughout this volume of Studies in Avian Biology, the ecology of sea ducks is a fascinating and important eld of inquiry that has grown substantially in recent years. For the purposes of this concluding chapter, we emphasize assimilation of the information presented in our volume as it pertains to understanding variation in demographic attributes and subsequently population dynamics, which provides a contextual structure for considering the various aspects of sea duck ecology throughout the annual cycle and is directly relevant for conservation of sea duck populations.
