Merlin

Dunlin Life History

Habitat

Habitat Shorelines

Dunlin nest in subarctic and arctic tundra, usually in wet areas with slight ridges and ponds. They feed on the edges of marshes and hummocks, usually not far from where they nest, as well as in coastal lagoons. In winter, Dunlin roost and forage in large flocks in saltwater areas such as estuaries and lagoons, but many forage in wet or flooded farm fields. When the tide is high, they gather on beaches, islands, or the upper edges of marsh. During migration, Dunlin stop over in sewage treatment ponds, moist harvested agricultural fields, and muddy edges of farm ponds, rivers, and lakes. Typically, they select areas where the water is less than 2 inches deep.

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Food

Food Aquatic invertebrates

Like other small sandpipers, Dunlin eat mostly invertebrates found in mud, fine sand, or soil. They forage by picking organisms they see or by probing into the substrate with their bills. Their sensitive bill tips enable them to detect prey by touch, allowing them to feed at night (which helps them take advantage of tidal cycles). They forage by repeatedly probing the area around them, then walking forward. Unlike similar-sized species such as the Curlew Sandpiper and Stilt Sandpiper, Dunlin normally does not insert the bill deeply into the substrate to find prey—in fact, most probe less than a quarter-inch deep. The prey they consume include earthworms, marine worms, midges, flies, craneflies, beetles, spiders, snails, blue mussels, small clams, and amphipods. Dunlin also eat small amounts of plant matter, mostly seeds. On rare occasions they eat tiny fish. They consume their prey immediately, using rapid bill movements and water tension in the bill to carry prey up to the mouth.

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Nesting

Nest Placement

Nest Ground

Males normally select the nest site. Nests are set in tundra vegetation, often near clumps of grass.

Nest Description

Males make several scrapes (depressions in the tundra vegetation) using their feet and breast, then sometimes line the scrape with willow leaves, sedges, and grasses. Females select the site that will serve as the actual nest. Nests average about 3.9 inches tall, with the interior 3.8 inches across and 2.5 inches deep.

Nesting Facts
Egg Description:

Olive, brown, buff, or blue-green, splotched with light brown to orange-brown.

Condition at Hatching:Active and covered with down.
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Behavior

Behavior Probing

In spring, male Dunlin arrive on the breeding grounds ahead of females and set up nesting territories as the snow and ice melt from the tundra. They mark territories with flights and song, a burry, reverberating, descending trill unlike any other sound of the tundra. In display, they fly over the territory with rapid, fluttering wingbeats, punctuated by short glides on cupped wings. They also sometimes call and sing from the ground, raising one wing. Their territories range from 0.5 to 18 acres in size. Male Dunlin drive other males from their territories, usually by chasing them in flight, but they feed peaceably with other males in ponds outside the territory. Dunlin are largely monogamous, and both sexes incubate the eggs and defend the young. At all other times of year, they are gregarious, gathering in small to very large flocks.

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Conservation

Conservation Low Concern

Partners in Flight estimates the global breeding population of Dunlin at 5.5 million (1.5 million in North America) and rates the species an 11 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Although Dunlin are still abundant, there is little information on population trends. Of the three breeding populations in North America, the one in northern Alaska appears to have declined by more than 30% since 2006 and now numbers around 500,000. The reasons for this decline are not known, but losses of wintering habitat could be involved.

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Credits

Andres, B. A., P. A. Smith, R. I. G. Morrison, C. L. Gratto-Trevor, S. C. Brown and C. A. Friis. (2012a). Population estimates of North American shorebirds, 2012. Wader Study Group Bulletin 119 (3):178-194.

Lutmerding, J. A., and A. S. Love (2017). Longevity records of North American birds. Version 2017.1. Patuxent Wildlife Research Center, Bird Banding Laboratory, Laurel, MD, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

Warnock, Nils D. and Robert E. Gill. (1996). Dunlin (Calidris alpina), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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