Correlation Between Nest and Duckling Survival of Mallards Breeding in Saskatchewan

Few studies have estimated reproductive and survival parameters of breeding ducks simultaneously, although such efforts can reveal relationships among vital rates. We estimated survival of mallard (Anas platyrhynchos) nests and ducklings on 8 study sites in south-central Saskatchewan during spring and summer 2000 and 2001. We observed a strong positive correlation between these parameters (r = 0.914) and through analysis of residual values found 14% of the relationship was explained by a predator-removal treatment, 26% by year effects, 44% by spatial variation, and 16% unexplained. Potential mechanisms include similar environmental factors influencing both parameters (e.g., predators) and positive density dependence. Information regarding covariation among vital rates is important in construction and interpretation of population growth models describing population dynamics of mallards and other upland-nesting ducks.