The choice of foraging methods of the Brown Dipper, Cinclus pallasii (Aves: Cinclidae)

Abstract

The Brown Dipper, Cinclus pallasii, forages for large prey by diving deeply among submerged rocks, and for small prey in shallow water by wading and pecking on the bottom. Foraging by diving entailed a higher energy cost but resulted in taking larger prey than foraging by wading-and-pecking. Foraging by diving was seldom observed from May to October, but increased from December to April, when the dippers came into breeding condition and the proportion of large prey in the benthic fauna increased. During the breeding season, adult dippers fed themselves mainly by foraging by wading-and-pecking, whereas those feeding nestlings and fledglings foraged by diving. The foraging methods employed was determined by the individuals being fed and the abundance of the large prey. Foraging by diving may be advantageous for individuals provisioning their young because of the high gross intake rate, but may be less advantageous for the foragers themselves because of the high energy cost. © 1990 Japan Ethological Society.