Evaluation of a mallard productivity model

A stochastic model of mallard (Anas platyrhynchos) productivity has been developed over a 10-year period and successfully applied to several management questions. Here we review the model and describe some recent uses and improvements that increase its realism and applicability, including naturally occurring changes in wetland habitat, catastrophic weather events, and the migrational homing of mallards. The amount of wetland habitat influenced productivity primarily by affecting the renesting rate. Late snowstorms severely reduced productivity, whereas the loss of nests due to flooding was largely compensated for by increased renesting, often in habitats where hatching rates were better. Migrational homing was shown to be an important phenomenon in population modeling and should be considered when evaluating management plans.