A DOUBLE-OBSERVER APPROACH FOR ESTIMATING DETECTION PROBABILITY AND ABUNDANCE FROM POINT COUNTS

Abstract

Although point counts are frequently used in ornithological studies, basic assumptions about detection probabilities often are untested. We apply a double-observer approach developed to estimate detection probabilities for aerial surveys (Cook and Jacobson 1979) to avian point counts. At each point count, a designated ''primary'' observer indicates to another (''secondary'') observer all birds detected. The secondary observer records all detections of the primary observer as well as any birds not detected by the primary observer.