Colony attendance and population monitoring of Least and Crested auklets on St. Lawrence Island, Alaska

Diurnal and seasonal patterns of attendance of Least Auklets (Aethia pusilla) and Crested Auklets (A. cristatella) were studied in 1987 at breeding colonies on St. Lawrence Island, Alaska. Numbers of auklets attending eight 200-m² plots on talus slopes were counted throughout the day by observers on 11 occasions through the breeding season. Numbers attending smaller plots were recorded on time-lapse film on 71 different days. Another 16 200-m² plots were censused for auklets using surface counts. Within-day patterns of attendance were extremely variable over small and large temporal scales. Peaks of attendance occurred in late morning and late evening, with a 7- to 12-hr period of absence in the middle of the day. Attendance varied markedly between days, and numbers were negatively correlated with wind speed and the magnitude of tidal oscillations. Patterns of attendance also varied with stage of breeding, and counts were least variable during incubation and early chick rearing. Whereas Least Auklet numbers peaked during prelaying, Crested Auklet numbers peaked during incubation. Counts indicated that auklets at Kongkok Bay have increased about twofold since studies in the mid-1960s. Recommendations are made for future monitoring of auklet populations.