Habitat

Mostly high- and low-arctic rocky coasts and tundra areas throughout Holarctic, extending south into boreal regions along Baltic and Scandinavian coasts. North American high-arctic population ranges from marshy slopes and flats in lowlands and foothills to well-drained clay and Dryas integrifolia (arctic mountain aven)-hummocked tundra slopes and flats, almost always close to moist areas such as wet marshes, streams, and ponds (Manniche 1910, Bird and Bird 1941, Salomonsen 1950, Parmelee and MacDonald 1960, Nettleship 1967, 1973; Meltofte 1985). Low-arctic habitat similar, with some concentration on sparsely vegetated habitats along mainland and island coasts with nearby ponds, streams, or tidal flats and beaches (Manning et al. 1956, Parmelee et al. 1967, Johnson and Herter 1989, Kessel 1989). All breeding habitat influenced strongly by availability of food nearby during incubation and early chick-rearing (see Food habits and Breeding: nest site, below).

In migration, largely coastal on rocky shores, but also sand, pebble beaches, and mudflats with seaweed/kelp debris and beds of mussels or cockles (Pelecypoda); some shorelines and beaches of inland freshwater lakes where they occur only during migration. Habitats frequented food-rich, usually crustaceans (Crustacea) or mollusks (Mollusca: mussels, cockles), sometimes forming critical staging sites (see Morrison and Harrington 1979): e.g., spring, Delaware Bay (New Jersey and Delaware) in second half of May to exploit horseshoe crab (Limulus polyphemus) egg-laying (Clark et al. 1993, Botton et al. 1994, Harrington and Flowers 1996); fall, Pribilof Is. (Bering Sea) in Aug for blowfly larvae (Calli-phora vomitora) associated with northern fur-seal (Callorhinus ursinus) carrion (Thompson 1973).

Almost exclusively coastal, mostly shorelines that are stony and rocky, with seaweed growth, but also common on mudflats, sandflats, and deltas (Stout et al. 1967). Generally, preferred habitats are ocean beaches and firm mudbanks along indented and sheltered coastlines, also sand or gravel beaches with estuaries, pools, wetlands, sometimes near inlets with large intertidal flats (Stout et al. 1967, Thompson 1973, Cramp and Simmons 1983, Morrison and Ross 1989, Barrantes and Pereira 1992).