Patterns of Colony Attendance and Censusing of Auklets at Buldir Island, Alaska

Daily and seasonal colony attendance patterns and census techniques for Crested (Aethia cristatella), Least (A. pusilla), and Whiskered (A. pygmaea) auklets were examined at Buldir Island, Alaska. Two daily peaks in colony activity were found throughout the breeding season: the first in the morning and early afternoon and the second just before dark. A new technique for estimating auklet populations was developed, based on the net movement of birds to and from the talus nesting area during the two peaks of activity. The new "Net Movement" technique yielded considerably higher estimates than those obtained using Bédard's (1969) method of estimating auklet populations by observation. Both techniques have advantages and disadvantages for censusing auklets, depending on circumstances.