American Dipper Life History

Habitat

The American Dipper is found on fast-flowing mountain streams and cold coastal streams of western North America and Central America. They forage in cascades, riffles and waterfalls along unpolluted waterways. Streambeds with cobblestones or coarse gravel are good habitat for their aquatic prey. Midstream or streamside boulders and large woody debris are necessary for perches. In winter, they often move downstream to use larger and deeper rivers, or even ponds and lakes provided the water remains ice-free.

Food

The American Dipper eats mostly aquatic insects and insect larvae but will occasionally take other invertebrates, as well as small fish or fish eggs. Its unique foraging style consists of diving beneath the water and walking along the streambed, often with wings outstretched to give traction against the rushing current. Main prey include larvae of caddisflies, mayflies, stoneflies, midges, and mosquitoes.Back to top

Nesting

Nest Placement

American Dippers nest in inaccessible, nearly vertical surfaces, often over rushing water. They typically place nests on large boulders, cliff ledges, on fallen logs, under an overhanging dirt bank, or underneath a bridge or culvert. They may use nest boxes when provided. They have even been known to place their nests behind waterfalls, so the birds must fly straight through falling water to access them. The female chooses the nest site.

Nest Description

The American Dipper’s nest is a two-part domed or ball-like structure with an entrance that always faces the water. The outer shell is primarily made of streamside mosses, though it may also contain leaves and bark from streamside trees. The inner portion of the nest is a pad of dry grasses and leaves. Both sexes build the nest and care for the young.

Nesting Facts

Behavior

The American Dipper spends much of its time foraging for aquatic invertebrates underwater, walking along the streambed and staying submerged for up to 15 seconds at a time. From a rock or log, they enter the water head first, propelled by partly opened wings. Underwater, the bird uses its wings to propel itself and move among foraging sites at the bottom of the stream. They are good swimmers, and can maintain their position on the surface of the water by paddling with the feet and wings. On land, the American Dipper nearly constantly dips its tail, flexing its legs and bobbing its entire body up and down, up to once per second—most rapidly when the bird is excited or disturbed. Some scientists think that this conspicuous movement helps the birds communicate despite the high background noise in the species’ turbulent environment. Male American Dippers maintain a territory year-round, often in the same place, leaving only in winter if ice cover becomes too great. Both sexes sing vigorously, beginning in late winter, from rock perches close to the water. Pairs are socially monogamous, and individuals with productive territories will pair up in consecutive years. Back to top

Conservation

Though American Dipper populations are difficult to count, numbers appear to have been stable since 1968, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 160,000 individuals and assigns the species a 12 out of 20 on the Continental Concern Score, indicating a species of relatively low conservation concern. Road construction and bridge-building along mountain streams has created good nesting sites for American Dippers. On the other hand, damming rivers can eliminate dipper habitat, and land uses such as logging and mining can affect water quality and reduce the availability of aquatic insect prey. Dippers are also susceptible to pollution including organic pollutants such as PCBs and heavy metals, and will abandon streams polluted with mining waste or sawdust from logging operations.

Credits

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Wilson, Mary F. and Hugh E. Kingery. (2011). American Dipper (Cinclus mexicanus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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