American Dippers Wintering Near Juneau, Alaska

Abstract

American Dippers (Cinclus mexicanus) in winter often foraged in habitats not used for nesting, including deltas of coastal creeks, and occasionally ponds, tiny streams, and ditches. The birds migrated altitudinally, at least 12 crossed a saltwater channel, and some apparently made wider, regional movements (5 to 50% of banded birds, with annual variation). In 2 relatively severe winters, we resighted fewer banded birds (<40% versus >65%) and annual survival was lower (<40% versus >50%), compared to 2 relatively mild winters. Birds foraging in the intertidal zone on deltas preyed on amphipods (low fat content) and fish, but this habitat was unavailable at high tide.