It has been hypothesized that proximity to edges, timing of nesting, nest concealment or inaccessibility, working singly or in concert, may explain variable nesting success of birds, but results have been mixed. I tested these hypotheses by determining fates and measuring nest-site features of 233 Ruddy Duck (Oxyura jamaicensis) nests near Minnedosa, Manitoba, Canada, during summers of 1994-1996. Mayfield nesting success averaged 41%. Discriminant function analysis was unable to segregate successful and destroyed nests. Results suggest that nesting success for this population of Ruddy Ducks is unpredictable, probably because a diversity of predators precluded choice of safe nest sites.