eWestern Birds

Foraging Interactions of the Great Egret in Upland Habitats

Cole J. Caldwell

ABSTRACT: Great Egrets (Ardea alba) foraging in grassy uplands near Arcata, California, used multiple strategies, foraging solitarily or in groups and commensally or noncommensally, in any of the four possible combinations. Egrets foraging commensally with cattle apparently benefited from the association on eight of the 21 observed occasions. Solitary foragers tended to use microhabitats along ditches and fences and were generally less active, made fewer errors, and captured larger prey than did group and commensal foragers. But group foragers, commensal and noncommensal foragers combined, captured more prey. Tidal fluctuations, prey types, and habitat structures likely modified foraging behaviors. There was no clear difference in rate of food intake, handling time, or foraging success by foraging strategy: a higher rate of capture of small prey by egrets foraging in groups compensated for the lower rate of capture of larger prey by solitary birds.

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