Egg viability, nest predation, and the adaptive significance of clutch size in prairie ducks.

Waterfowl begin incubating their eggs before the clutch is completed. Egg viability declines during the period of egg laying if eggs remain unincubated. Early nest attendance may slow the rate of decline in viability. Declining egg viability associated with delayed incubation may play an important role in determining the most productive clutch size in temperature-breeding waterfowl. The benefit of laying additional eggs is offset by the reduced value of the first-laid eggs, which suffer lowered viability and greater risk of predation.-from Authors