Effects of investigator disturbance on breeding success of Atlantic puffins Fratercula arctica

Reliable data on the breeding success of Atlantic puffins Fratercula arctica are difficult to obtain because they readily desert their eggs when disturbed. Previous studies on puffins in Britain developed a visiting regime to study sites that caused no reduction in breeding success compared to undisturbed controls. However, reduced success following application of similar methods in other areas suggested that the response of puffins to disturbance may vary geographically and perhaps temporally. We designed a study to test whether that visiting regime reduced breeding success on Great Island, Newfoundland, in 1992. We monitored success in 1993 and 1994 to determine if the effects of our disturbance in 1992 persisted through subsequent breeding seasons. Chick productivity was reduced by 38% in disturbed study plots compared to control plots in 1992. Effects of disturbance persisted one year and were not apparent two years after the disturbance. We recommend that investigations of puffins be confined to the nestling period and that researchers include carefully designed controls to ensure that their study results are unbiased.