Activity Patterns of Marbled Murrelets in Old-Growth Forest in the Queen Charlotte Islands, British Columbia

Abstract

Activity patterns of Marbled Murrelets (Brachyramphus marmoratus) in old-growth forest were compared at two sites in the Queen Charlotte Islands, British Columbia. Number of detections peaked in late July at both sites. More activity was recorded on cloudy mornings than on clear mornings and the duration of activity was greater on cloudy days than on clear days. Number of detections, number of calls and duration of the activity period per survey were highly variable and were correlated on a coarse scale (seasonally) but not always on a fine scale (weekly). Activity levels at the two stations were correlated over the entire season but not on a monthly or weekly basis. Detections were always more numerous in the morning than in the evening. Most detections were auditory only, but birds were seen in 20 and 26% of detections at the two sites. Approximately half of visual detections were of silent birds. Most birds sighted were either singles or in pairs and the majority of single birds were silent and tended to fly at lower altitudes than grouped birds. Knowledge of the behavior of Marbled Murrelets at inland locations is essential for the design of survey methodology and interpretation of survey results.