Importance of individual species of predators on nesting success of ducks in the Canadian prairie pothole region

We followed 3094 upland nests of several species of ducks. Clutches in most nests were lost to predation. We related daily nest predation rates to indices of activity of eight egg-eating predators, precipitation during the nesting season, and measures of wetland conditions. Activity indices of red fox (Vulpes vulpes), striped skunk (Mephitis mephitis), and raccoon (Procyon lotor) activity were positively correlated, as were activity indices of coyote (Canis latrans), Franklin's ground squirrel (Spermophilus franklinii), and black-billed magpie (Pica pica). Indices of fox and coyote activity were strongly negatively correlated (r = -0.51), as were those of badger (Taxidea taxus) and skunk (r = -0.46). Nest predation rates in the early part of the breeding season were positively related to indices of fox, American crow (Corvus brachyrhynchos), and badger activity. Predation rates in the latter part of the season were positively related to indices of fox and skunk activity. Predation rates on early-season nests were lower in areas and years in which larger fractions of seasonal wetlands contained water. For late-season nests, a similar relationship held involving semipermanent wetlands. We suspect that the wetland measures, which reflect precipitation during some previous period, also indicate vegetation growth and the abundance of buffer prey, factors that may influence nest predation rates.