Experimental evidence for density-dependent survival in mallard (Anas platyrhynchos) ducklings

摘要: It is unresolved to what extent waterfowl populations are regulated by density-dependent processes. By doing a 2-year crossover perturbation experiment on ten oligotrophic boreal lakes we addressed the hypothesis that breeding output density dependent. Wing-clipped mallard (Anas platyrhynchos) hens were introduced with their own brood and then monitored for 24 days. Predicted responses per capita duckling hen survival would be lower in high-density than low-density treatments. Survival was evaluated model fitting program MARK. Density, year, lake used as main effects, while day after introduction, weather harshness index, presence of covariates. Daily ducklings treatment, but this effect year The highest-ranking also included positive age hens, negative harsh weather. Density did not affect female although there prominent effect. effects introduction This first study report experimentally natural setting. Implications population dynamics management harvested far-reaching if such regulation occurs some years, others.