Dunlin

Like many other New Jersey shorebirds, dunlin are migrants, breeding in the northern Arctic. In North America, their breeding range stretches from southwestern Alaska and the Aleutians north and east to James Bay. Unlike their more particular cousin, the red knot, dunlin inhabit a variety of habitats on their breeding grounds, including tundra, wetlands, melt water edges, wet meadows, shallow marshes, and mudflats.

In winter, the Atlantic population of dunlin ranges from Massachusetts in the north to Northern Veracruz, Mexico in the south. While migrating and wintering, dunlin tend to prefer beaches and coastal mudflats, but they are adaptable here as well. If these coastal habitats are unproductive, they will utilize alternative habitats inland such as farmland, meadows or other conservation lands. Additionally, substantial numbers of dunlin will regularly winter inland along the Gulf of Mexico, the central valley of California, and other areas.

Dunlin forage mainly by sight on their breeding grounds, capturing insect prey such as larval midges, beetles, and other larval and adult flies. Outside the breeding season, they forage mainly by touch, probing the sand or mud with their long bills for marine worms, crustaceans, and mollusks.

Male dunlin arrive on the breeding grounds throughout May and begin to establish territories prior to the arrival of the females. Once a mate has been found, dunlin are monogamous during the season, and they will often re-form pairs in subsequent years on the same territory.

Nests are constructed on small hummocks on the ground and are little more than a compacted scrape lined with grass and other vegetation. The female lays four spotted green to olive-buff eggs, and both sexes incubate for about three weeks. The chicks are able to walk within hours and regulate their own body temperature within days. Females tend the brood for about a week, while the male will remain with the chicks until they fledge at about three weeks of age. Juvenile dunlin often form flocks of their own at interior locations before joining the adults at coastal staging areas prior to fall migration. During this time, both juvenile and adult dunlin molt into their winter plumage before heading south. For this reason, they are usually one of the last shorebirds to arrive at southern beaches in the fall.

Due to their wide geographic distribution and stable numbers overall, dunlin are not considered threatened by any major conservation authority. However, some populations (notably the Pacific subspecies) are in decline. It is suspected that habitat loss due to contamination and continued coastal development may be a factor in this drop. Similarly, global climate change could have as-yet unseen effects on dunlin, whose far-northern breeding territories make them especially vulnerable.

Additionally, dunlin frequently stage in and utilize areas adjacent to protected shorebird reserves. This highlights the need for the protection of migratory flyways and not just isolated pockets of protected habitat.