Dunlin (Calidris alpina)

Description

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Dunlin fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Dunlin description

The dunlin (Calidris alpina) is one of the hardiest of all shorebirds, breeding far north in the Arctic region and migrating southwards before the onset of winter ⁽³⁾. This species is also renowned for its beautiful breeding plumage, which is distinguished by the reddish cap, bright reddish-brown back and black belly patch, which extends behind its black legs. The head and breast are pale brown. Outside of the breeding season, the dunlin is light brownish-grey with a brownish back, white underparts and a brownish band streaking across the upper breast ^{(2) (4)}.

Also known as

black-breast, black-breast dunlin, purre, red-backed sandpiper.

French

Bécasseau variable.

Size

Length: 16 - 22 cm ⁽²⁾

Weight

48 - 64 g ⁽²⁾

Dunlin biology

The male dunlin arrives at the breeding grounds first, and pairs are established upon the females’ arrival ⁽⁴⁾. The males attract a partner by performing display flights, which consist of short glides with stiff arched wings, interrupted by rapid, shallow flutters ⁽²⁾. The male makes a few scrapes on the ground, which are then lined with grass, sedges and leaves. The female chooses one of the scrapes as the nest and finishes its construction ⁽⁴⁾. The nest is often concealed in vegetation and sometimes in a tuft or tussock ⁽⁵⁾. Usually 4 eggs are laid, which are then incubated for 20 to 22 days. The young leave the nest shortly after hatching, but are tended by the adults until they are ready to fledge, usually at about 19 days ⁽⁴⁾. 

Outside of the breeding season, the dunlin is highly gregarious, travelling in groups of up to 1,500 while migrating and residing in groups numbering hundreds of thousands at the wintering grounds. This species is active both during the day and at night ⁽⁵⁾. It feeds by probing and jabbing with its long bill in the substrate ⁽²⁾. At the breeding grounds, insects and insect larvae are the most important source of food, but elsewhere its diet is more varied, feeding on worms and small snails, as well as insects, crustaceans, bivalves, plant matter and occasionally small fish ⁽⁴⁾.

Dunlin range

The dunlin has a very wide distribution, occurring across nearly all Arctic regions. Its breeding range stretches from east Greenland, across the Russian Arctic to the Alaskan coast of the Bering Sea. There is also an isolated population that breeds in the east Canadian Arctic ^{(5) (6) (7)}. 

A migratory species, the dunlin has a number of sub-populations that each has differing migration behaviours. For instance, the sub-population that breeds in north-east Greenland migrates through Iceland, Britain and western France to arrive in its west African wintering grounds from late July, returning again between March and early April ⁽⁵⁾.

Dunlin habitat

During the breeding season, the dunlin is found on moist, boggy ground with tussock tundra, as well as wet coastal grasslands, salt marshes and wet upland moorland. Outside of the breeding season, this species prefers mudflats, but occurs on a wide variety of fresh and brackish habitats, including lagoons, muddy shores, tidal rivers, flooded fields, sandy coasts, lakes and dams ⁽⁵⁾.

Dunlin status

The dunlin is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾.

Dunlin threats

With an extremely large range and a relatively large population, the dunlin is not at immediate risk of extinction. However, there are a great number of threats to this species, with the loss of its breeding habitat through afforestation particularly problematic ⁽⁵⁾. 

In the winter, this species is restricted to a small number of estuaries, so it is vulnerable to any changes in this habitat, for example through land reclamation and the invasion of alien plant species. Important migratory stop-over habitats on the Baltic Sea coastline are also threatened by petroleum pollution, wetland drainage for irrigation, peat-extraction, reedbed mowing and burning, and changing land practices which lead to scrub and reed overgrowth ⁽⁵⁾. 

The dunlin has also been extensively hunted in the past, although this is now a lesser threat ⁽²⁾, and it is susceptible to avian influenza ⁽⁵⁾. In some areas, introduced predators such as the hedgehog (Erinaceus europaeus) have greatly reduced the breeding success of this species ⁽⁶⁾.

Dunlin conservation

In North America, the dunlin is protected by the North American Migratory Bird Treaty Act of 1918, which protects this species and its eggs from hunting and collection ⁽²⁾. In the UK, this species is also well protected in Special Protected Areas, with around 74 percent of the total breeding population found in such reserves ⁽⁶⁾. 

A conservation priority for the dunlin is the development of monitoring across its range so that overall population trends may be determined ⁽²⁾.

Find out more

Find out more about the dunlin:

• Avibirds European Birdguide Online - Dunlin:
  http://www.avibirds.com/euhtml/Dunlin.html

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Glossary

Avian influenza

Also known as “bird flu”, a contagious disease caused by any strain of influenza virus that is carried by and primarily affects birds.

Bivalve

A group of aquatic molluscs in which the soft parts are encased in a shell consisting of two parts, known as valves.

Brackish

Slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.

Crustaceans

Diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.

Incubate

To keep eggs warm so that development is possible.

Larvae

Stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Tundra

Treeless, grassy plains characteristic of Arctic and sub-Arctic regions. They are very cold and have little rainfall.

References

1. IUCN Red List (August, 2011)
   http://www.iucnredlist.org/
2. Warnock, N.D. and Gill, R.E. (1996) Dunlin (Calidris alpina). In: Poole, A. (Ed) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
   http://bna.birds.cornell.edu/bna/species/203/
3. Schulenberg, T.S. (2010) Dunlin (Calidris alpina). In: Schulenberg, T.S. (Ed) Neotropical Birds Online. Cornell Lab of Ornithology, Ithaca. Available at:
   http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=153301
4. Avibirds European Birdguide Online - Dunlin (August, 2011)
   http://www.avibirds.com/euhtml/Dunlin.html
5. BirdLife International - Dunlin (August, 2011)
   http://www.birdlife.org/datazone/speciesfactsheet.php?id=3056
6. Joint Nature Conservation Committee - Dunlin (August, 2011)
   http://jncc.defra.gov.uk/pdf/UKSPA/UKSPA-A6-67A.pdf
7. Critical Site Network Tool (August, 2011)
   http://csntool.wingsoverwetlands.org/csn/default.html