Colony attendance by the Atlantic Puffin (Fratercula arctica) was examined to investigate daily and seasonal patterns of variation, and to determine the biological or environmental factors, if any, which serve as useful predictors of such variation. Observations were made during the pre-laying and incubation stages of the breeding season on a study plot at a colony on Gull Island, Witless Bay Seabird Ecological Reserve, Newfoundland, Canada. The number of birds on the surface of the colony increased through the day, but the peak number differed between consecutive days. Colony attendance showed a possible cyclical trend across days with a periodicity ranging from two to six days. Residency time of individual birds was associated with the extent of colony attendance, suggesting a positive feedback loop between individual short-term turnover and numbers present on the breeding slope. Neither weather nor presence of large gulls was related to puffin attendance. The correlation between residency time and colony attendance suggests that puffins may be more confident on land when surrounded by other conspecifics. With the high variability and no obvious factors that influence attendance, the use of colony surface counts of individuals to infer population parameters is likely limited in this species.