Visual and olfactory concealment of duck nests: in uence on nest site selection and success

Selecting a nest site is an important decision for waterfowl. Because most nest failure is due to depredation, the primary selective pressure in choosing a nest site should be to reduce depredation risk. This task is dif cult, however, because predators use differing tactics to locate nests, such as olfactory or visual cues. The purpose of this research was to evaluate both the olfactory and visual components of waterfowl nest site selection and nest depredation in North Dakota. We located waterfowl nests, monitored them until termination (hatched or depredated), and collected both visual and olfactory concealment characteristics of nest sites and paired random sites in 2006 and 2007. Waterfowl nest sites and random sites did not differ in their olfactory concealment characteristics. However, waterfowl did select nesting sites with greater lateral concealment than random sites, a visual characteristic. The only difference found between successful and depredated nests consisted of lateral dispersion, an olfactory concealment characteristic. These results indicate that while waterfowl may select nest sites based on visual concealment characteristics, those characteristics were not predictive of nest success. Olfactory concealment characteristics may be more important for nest success in our study area because the dominant nest predators, including raccoons (Procyon lotor) and striped skunks (Mephitis mephitis), primarily utilize olfactory cues to locate nest sites.