ABSTRACT
Abstract. Sea ducks spend the majority of their life in a cold, marine environment where they must dive, often to great depths, consuming enough food to maintain energy balance. The food consumed is hard shelled, cold, and of low energetic value; yet sea ducks excel when faced with many energetic and thermoregulatory challenges, especially for a relatively small-bodied marine endotherm. The energy cost of thermoregulation and intensive work required to collect daily rations are especially high for sea ducks at high latitudes where they must cope with limited daylight for foraging under harsh winter conditions. To offset these high energetic demands, sea ducks must optimize their decisions about habitat choice, foraging behavior, and prey selection. Foraging behavior strives to maximize gross energy gain and minimize costs to reach energy balance, sometimes under the most extreme of conditions such as the polynyas of the Belcher
Islands and St. Lawrence Island. Studying sea ducks under these conditions is equally challenging but through the combined research effort of agencies, organizations, academics, and individuals, we have made great strides in gaining information on the foraging ecology of sea ducks. In this chapter, we review the general aspects of sea duck foraging ecology and diving behavior, foraging energetics, and modeling of energy balance. Each of these topics is discussed in detail, but it is not our intention to review all of the literature available, but rather to highlight the particular discoveries and developments that have greatly increased our understanding of the foraging ecology of sea ducks.
