Courtesy Kenn Kaufman
Several subspecies of Dunlin breed in North America. Western populations breed coastally from western Alaska north through the Arctic National Wildlife Refuge to Canada’s Northwest Territories. Eastern populations breed from the peninsulas of Canada’s Nunavut Territory, southward along the western shores of Hudson Bay. Along the Pacific coast, Dunlin winter from Alaska to the state of Nayarit, Mexico, and along the Atlantic and Gulf coasts from Massachusetts to Northern Veracruz, Mexico.
A legend for the range map to the right can be found here
During the breeding season, Dunlin inhabit a variety of landscapes: tundra, shallow marshes, melt water edges, wet meadows, and mud flats. Wintering and migrating Dunlin frequent shorelines and estuaries. Inland meadows, farmland, and conservation lands provide vital alternative habitats, particularly when coastal habitats are unproductive.
Outside the breeding season, Dunlin probe in sand or mud for marine worms like the pile worm, crustaceans like beach hoppers, and mollusks like the Baltic macoma clam. Migrating Dunlin often feed at night. On the breeding grounds, this shorebird forages by sight, capturing larval midges, adult flies, and beetles.
Throughout May, male Dunlin arrive on their breeding grounds and usually establish territories in advance of their mates’ arrival. Pairs often re-form in successive years and are monogamous for the season. Males perform aerial displays to maintain pair bonds and create one or more scrapes for the female to inspect. The cup is first compacted with the feet, then widened with the breast, and lined with a loose collection of leaves and grasses.
Females lay four buff, blue-green, or olive eggs, splotched and scrawled with warm browns. Both sexes incubate the eggs for about three weeks, at which time the chicks emerge, ready to walk, preen, forage, and hide. Within a few days, they can keep themselves warm. Females tend the brood for about six days, but males usually remain until the young can fly. Juvenile Dunlin form flocks and move to interior locations before joining adults on coastal staging areas prior to fall migration.
Dunlin migrate in large, sometimes enormous, flocks that baffle predators with rapid, synchronized maneuvers. The Dunlin’s short to medium-range migration begins in March and follows traditional routes along both coasts and interior flyways, depending on the subspecies. North American Dunlin molt in September before migrating south from staging areas near their breeding grounds. As a result, Dunlin are one of the last shorebirds to arrive on the shores of the United States in the late fall.