Risk of Predation on Waterfowl Nests in the Canadian Prairies: Effects of Habitat Edges and Agricultural Practices

Abstract

Habitat fragmentation has been postulated as a cause of lower nest success in many species of birds, potentially due to creation of additional edges. In this study we tested the hypothesis that predation on artificial waterfowl nests was influenced by habitat edges. Data from dense nesting cover supported the ecological trap hypothesis, while predation risk was not related to distance (0-150 m) from habitat edge in idle pasture or delayed hay fields. Nest survival was heterogeneous within the 4-week sampling period with nests exhibiting increased survival with time of exposure. Nest survival also differed among habitat types. Daily survival rate was highest in dense nesting cover and delayed hay, while idle pasture and rights-of-way exhibited similar but lower nest success. These results suggest that agricultural practices have profound effects on waterfowl nesting success in upland environments. Nest survival was higher in spring than in summer in one out of three years. In all years and habitats, significantly more mammals than birds depredated waterfowl nests. The relative importance of the two classes of predators was similar among delayed hay, dense nesting cover and rights-of-ways, but differed from idle pasture where avian predation was higher.