Monitoring Surveys of the Parakeet Auklet (Aethia psittacula, Charadriiformes, Alcidae): Daily and Seasonal Attendance Patterns in North Pacific Colonies

Resumo

The daily and seasonal patterns of colony attendance for the parakeet auklet were examined on Buldir and St. Paul islands, where fieldwork was conducted in 2001, 2002, and 2004, respectively. The timing of breeding events for the parakeet auklet was measured by monitoring the productivity plots on Buldir Island, and the timing of chick hatching was determined by observing birds that carried food to chicks on St. Paul Island. On Buldir Island, direct observations of birds on water were used to collect data on parakeet auklet attendance as it was impossible to count the birds directly on land because of lush vegetation covering the slope of the colony. The birds were counted on a designated plot on water below the colony. On St. Paul Island, observations of birds on both the water and the cliffs were used to collect data on parakeet auklet attendance patterns. On each count day, the birds present at the plot were counted every 15 min. Parakeet auklets have two peaks in their attendance pattern on the water near the colony on Buldir Island. As the breeding season progressed, the peak timing of birds moved slightly toward the afternoon. On St. Paul Island, prior to egg-laying, the numbers of parakeet auklets attending the breeding colony peaked in the morning. As the breeding season progressed, the peak of bird attendance at the colony broadened and shifted toward the evening. During the chick-rearing period, birds arrived at the land plot throughout the day, but there was a peak in the numbers attending in the evening. The observations showed that the weather conditions strongly influenced the numbers of birds present at the plot. Strong winds decreased the number of parakeet auklets in the nearshore area. On windy days, the birds left the plot earlier than usual.