Dunlin
Dunlins are chunky, medium-sized sandpipers, commonly sighted across North America during migration between their wintering areas on the Atlantic and Pacific coasts and their breeding grounds in Alaska and extreme northern Canada. Distinctive in plumage, bill shape, and voice, they are also among the most variable of shorebird species, with significant differences in morphology and size across their range.

Dunlins breed on the coastal tundra of Alaska and the Northwest Territories, as well as the western margins of Hudson Bay and James Bay. They also breed in polar and subpolar coastal areas on Iceland, Greenland, and Britain, and across Scandinavia and northern Russia to the Chukchi Peninsula. North American Dunlins migrate across the entire continent, stopping in various wetland areas en route to their wintering grounds along both coasts from British Columbia to Baja California, and from Massachusetts to the Yucatan Peninsula. Dunlins breeding in the Old World winter in temperate regions of Europe, Asia, and West Africa.
Dunlin Range Map

Dunlins show wide regional variation in bill and wing length as well as overall plumage and body mass. Size differences vary clinally across breeding longitudes, with the smallest races in northeast Greenland, increasing gradually across northern Europe and Russia, with the largest races in Alaska and Canada. Bill length in the largest Dunlin races may be about 30 percent greater than in the smallest. At present, taxonomists have not reached widespread consensus on recognition of subspecies.

Dunlins feed on coastal and intertidal invertebrates, often in mudflats. They locate prey by feel, probing or jabbing with their long bills. Dunlins often forage with their bills open. Prey vary by season and location; preferred items include clams, worms, insect larvae, and small crustaceans.

Dunlins generally leave their breeding grounds later than most other shorebird species, after fattening up and completing their molt into winter plumage. (Dunlins may weigh up to fifty percent more at the end of summer than they do upon arrival on their wintering grounds.) They initiate migration in apparent response to favorable weather conditions, moving in large flocks of more than 1,000 birds.

In contrast to their gregarious and generally unaggressive nature in winter, Dunlins are territorial during the breeding season, nesting in isolation from other pairs. The species is generally monogamous. Nests are cup-shaped, built on the ground out of grass and willow leaves. Clutches generally consist of four eggs; both sexes incubate, with females apparently bearing primary responsibility soon after laying, and males incubating more as hatching draws near.

Immediately upon hatching, young Dunlins can walk. They leave the nest within a few hours after hatching. Parents assist young in finding areas of abundant food supply, but young feed themselves. They remain close to their parents for three to four weeks, until they are able to fly.

Description: Dunlins are medium-sized sandpipers, measuring approximately 7 inches in length. Members of the Dunlin's genus (Calidris) can be extremely difficult to identify. A key distinguishing feature of the Dunlin is its long, slightly decurved bill. Black legs and various subtleties of plumage may help birders further in clinching the Dunlin's identity in the field.

During the breeding season (April to August), adult Dunlins have a distinctive solid black patch on their bellies, with relatively bright rufous upperparts, and a rufous cap. (The Rock Sandpiper is the only other Calidris sandpiper with a black belly, but its black patch does not extend far behind the legs, as the Dunlin's does.) During fall and winter, adult Dunlins are quite drab, with pale bellies and dull brown on their heads, breasts, and upperparts. In all seasons, Dunlins show a brown central wedge through the center of their rumps and tails. Sexes are similar.

Juveniles have distinctive plumage, seen only on the species' breeding grounds. Feathers on back are black, edged in light orange-brown. Breast is finely streaked; some black is present on belly, but not as a bold, solid patch.

Voice: Call is a distinctive rasping chrrrree. Vocalization in display flight is a series of pulsing trills.


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