Several species of ducks defecate when flushed from their nests, but it is unclear why. Possibly, this behavior reflects manipulation by parasites to facilitate transmission. We analyzed feces of 32 incubating Somateria mollissima (Common Eider) for evidence of parasite transmission stages. We found a total of only 11 parasite transmission stages (identified as digenean and nematode eggs) in feces of 3 different hens, suggesting that defecation around the nest has a low probability of leading to parasite transmission. Other hypotheses for defecation behavior in this and other duck species (repulsion of egg predators, weight loss to increase hen maneuverability to escape predators) appear insufficient to explain its persistence.