Habitat

Subarctic and alpine tundra and taiga, variable, ranging from dry heath uplands to poorly drained hummocky, grass-sedge, dwarf shrub, and mossy lowlands. In Manitoba, nests in wet, hummocky taiga bogs characterized by numerous dry lichen (Cladonia spp.)- and heath-topped hummocks and mounds (usually 30–75 cm high); sparsely scattered, stunted black spruce (Picea mariana) and tamarack (Larix laricina); and abundant dwarf shrubs (e.g., dwarf birch [Betula glandulosa] and lapland rosebay [Rhododendron lapponicum]). Also nests in low-lying wet, flat sedge (Carex spp.) tundra with widely distributed shrubs and small hummocks (usually 10–20 cm high); and in upland dry flat heath tundra characterized by dense, prostrate lichen associations (Skeel 1976a, 1983). In Mackenzie River Delta, Northwest Territories, nests in various habitats: in one study exclusively in lowlands with well-developed, low-centered polygonal ground, distinguished by water depth >0.5 m and presence of prominent margins and central mounds, selecting areas with 15–40% standing water and a vegetation cover of mixed dwarf shrub (<35%) and grass or sedge (>15%; Dickson et al. 1989); in another study, in same habitat and also in wet sedge tundra, with no birds nesting on upland tundra (Gratto-Trevor 1994); in a third study, primarily in dwarf shrub-heath and high-centered polygon upland habitats, also in willow (Salix)-sedge and low-centered polygon lowland habitats (Slaney and Co. 1974). In w. Alaska, nests in wet, flat, dwarf-shrub tundra, also on dry dwarf-shrub ridges and steep slopes, all characterized by abundant berry-producing shrubs (B. McCaffery pers. comm.); at Denali (formerly Mt. McKinley), AK, in rolling, open, usually moist tundra among sedge hummocks (Murie 1963). In Churchill, Manitoba (EPM), and w. Alaska (B. McCaffery pers. comm.), feeds on nearby ericaceous heaths and intertidal flats.

On fall migration, uses a variety of terrestrial and coastal habitats: ericaceous heaths in e. Canada (Todd 1963); coastal tundra in Alaska (Handel and Dau 1988); also meadows, fields, intertidal flats, oyster banks (Sprunt and Chamberlain 1949), sandy beaches, rocky shores, river mouths and estuaries, salt marshes, lagoons, and upper beaches and dunes.

Mostly tidal flats (mud preferred over sand); also hard mudbanks in South America. To a lesser extent, coral reefs, lagoons, marshes, swamps, estuaries, sandy beaches, and rocky shores. Also mangroves (from Florida south and on Galapagos Is.), where birds forage in surrounding mud, roosting in trees at high tide. Also (especially at high tide) terrestrial habitats, including dunes, meadows, short grass, fields, and highland and alpine meadows.