Habitat

See Figure 2 . See also: Food Habits: feeding. C. a. arcticola: in Prudhoe Bay, AK, generally moist-wet tundra, often in areas with ponds, polygons, and strangs (short, sinuous ridges that form perpendicular to the direction of the local hydrologic gradient), commonly found in recently formed landscapes such as drained thaw lakes (D. M. Troy pers. comm., Meehan 1986). In a comparison of 4 habitat types near the Beaufort Sea (Wet, Saline Coastal Tundra dominated by Carex subspathacea and Puccinellia phryganodes; Nonsaline Coastal Tundra; Dry Coastal Tundra; and Inland Tundra), significant differences in use by Dunlin: nests/km2—Inland 8.0, Saline 4.5, Nonsaline 6.0, Dry 0.5; birds/km2 detected in breeding season—Inland 14.5, Saline 8.3, Nonsaline 8.6, Dry 0.4; birds/km2 detected in postbreeding—Inland 9.8, Saline 34.3, Nonsaline 20.8, Dry 1.8; overall, a significant lack of use of coastal dune areas (TERA 1993). In n. Alaska, shoreline silt barrens important habitat for postbreeding Dunlin (Andres 1989).

C. a. hudsonia: in n. Ontario, wet tussock and peat-hummock tundra (Cadman et al. 1987). In Manitoba, wet tundra, wet sedge marshes (Jehl and Smith 1970).

C. a. pacifica: on Yukon-Kuskokwim Delta, AK, coastal sedge graminoid meadow dominated by Carex ramenskii, C. deschampsioides, and C. rariflora and having numerous shallow ponds and tidal distributaries (Holmes 1970, REG). Highest postbreeding densities of Dunlin on central Yukon-Kuskokwim Delta found on unvegetated intertidal flats, average >900 birds/km2, but densities exceeding 1,800 birds/km²recorded on major portions of the area (Gill and Handel 1990).

See also Food Habits: feeding. Common on coastal estuaries, bays, interior seasonal wetlands, flooded fields, and other agricultural lands. At Bolinas Lagoon, CA, foraging radio-marked birds located 94% of time on mudflats, 6% on outer coastal reef (NDW). In upper Mad River estuary, CA, 85% of birds observed in water, 14% on sand, 0.4% on cobble, and 0.1% on mud (Colwell 1993). In Central Valley, CA, 50% of 132,663 birds located in agricultural croplands, 38% in managed wetlands, 6% in evaporation ponds, 5% in sewage ponds, and 1% in other habitat (Shuford et al. 1993). Also feed in interior seasonal wetlands, flooded rice fields, flooded pastures, and grazed pastures (Warnock et al. 1995). Rice-growing regions in s. U.S. apparently important winter sites for C. a. hudsonia (Remsen et al. 1991, S. Skagen pers. comm.). In U.K., numbers on coast negatively correlated with presence of Spartina grass (Goss-Custard and Moser 1988); this deserves further attention in North America, where Spartina is expanding on the West and East coasts.