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When Bourget's results are compared with those of Choate (1966) and Clark (1968), the higher nesting success in 1969 was caused by two things. First, in Bourget's study 54% of nests were in the open, with 46% located under nesting shelters which afforded better protection against avian predators. Secondly, human interference in the 1969 study did not involve long periods of disturbance while searching for nests, as performed by Choate and Clark. The present research primarily involved observations from a blind which resulted in much shorter periods of disturbance to the colony. During this study, the observer's interference affected the breeding chronology of herring gulls (Larus argentatus), great black-backed gulls (Larus marinus), and common eider (Somateria mollissima). As a result of human disturbance the breeding cycles of the species concerned were delayed especially on the two major islands. It is probable that human disturbance, gull populations, gull species composition, and nesting cover have much more influence on common eider nesting success than eider nesting density on a given island.