Modelling the energy budget and prey choice of eider ducks

We developed an energy and heat budget model for eider ducks. All relevant processes have been quantified. Food processing, diving costs, prey heating, the costs of crushing mussel shells, heat losses during diving as well as during resting, and heat production as a result of muscle activity are distinguished. In the report, blue mussels are regarded as food source, and we computed the profitability of small to large sized mussels for a duck. Finally, the possibility for a duck to survive winter conditions when feeding on a mussel population with a known size frequency distribution is calculated during a simulation run. Conditions for four sites in The Netherlands, France, Denmark and Sweden are regarded and there implications for the foraging behaviour of an eider duck are computed. The implications of the presence of barnacle epibionts are briefly discussed.