thumb|Sanderlings in [[Kanagawa Prefecture|Kanagawa, Japan]]

The sanderling (Calidris alba) is a small wading bird. It is a circumpolar Arctic breeder, being among the most extreme northern breeding birds in the world, nesting only on the coldest tundra, north of the 5°C July isotherm; in Europe, its southernmost breeding locality is Svalbard, where only a handful (5–15) pairs breed. which has led to the suggestion that it should be placed into a monotypic genus Crocethia. More recent reviews indicate that the sanderling is a fairly typical "stint" or small sandpiper and should be retained along with the knots and other relatives in the genus Calidris.

This bird is similar in size to a dunlin, but stouter, with a thick bill. It shows a strong white wingbar in flight, and runs along the sandy beaches it prefers with a characteristic "bicycling" action of its legs, stopping frequently to pick small food items. It eats small crabs and other small invertebrates. In spring, birds migrating north from South America consume large numbers of horseshoe crab eggs in the Delaware Bay area.

In spring, the birds arrive on their High Arctic breeding grounds (see map) at the end of May or in early June, where they lay 3–4 eggs in a ground scrape from mid June to mid July.

The sanderling is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

Description

The sanderling is a small plump sandpiper, in length. Its weight ranges from . The winter bird is very pale, almost white apart from a dark shoulder patch. This is the source of the specific name, alba, which is the Latin for "white". Later in the summer, the face and throat become brick-red. The juvenile bird is spangled black and white, and shows much more contrast than the adult.

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! colspan="2" | Standard Measurements The genus name is from : or : , a term used by Aristotle for some grey-coloured waterside birds. The species name, alba, is Latin for "white".

The sanderling consists of two subspecies:

  • C. a. alba, <small>(Pallas, 1764)</small>, breeds on Ellesmere Island, north & east Greenland, Svalbard, Franz Josef Land and the Taymyr Peninsula
  • C. a. rubida, <small>(Gmelin, 1789)</small>, breeds in northeast Siberia, Alaska and northern Canada

Behaviour

Feeding behaviour

right|thumb|Sanderling feeding

Sanderlings feed on invertebrate prey buried in the sand in the upper intertidal zone. In North America, this diet largely consists of the isopods Excirolana linguifrons, Excirolana kincaidii, and the mole crab, Emerita analoga. When the tide is out, these crustaceans live in burrows some way beneath the surface. When the tide comes in, they move into the upper layers of sand and feed on the plankton and detritus that washes over them with each wave. They then burrow rapidly down again as the water retreats. They leave no marks on the surface, so the sanderlings hunt for them by plunging their beaks into the sand at random, consuming whatever they find. Their bills can penetrate only and as the water swirls around and retreats, the sand is softer; this makes it easier for the birds' beaks to penetrate further. In the spring, when much breeding activity is taking place in the benthic community, there may be as many as 4000 invertebrates per square metre, but their average size is smaller than later in the year. The birds appear to rush madly around at the edge of the surf, but in reality they are maximising their chances of catching as many prey animals as possible when they are at their most vulnerable near the surface.

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File:Sanderling-11MAY2017.JPG|Sanderling in Monterey, California

File:Sanderling (Calidris alba) breeding plumage.jpg|Breeding plumage, Farmoor Reservoir, Oxfordshire

File:Sanderling (Calidris alba).jpg, Amrum.jpg|Sanderling on the island of Amrum, Schleswig-Holstein

File:Sanderling-floreana.jpg|Floreana Island, Galapagos Islands

File:Calidris-alba-001.jpg|Running

File:Sanderlings (72649).jpg|Sanderlings feeding in Quogue, New York

File:SanderlingsRunningFromWavesCropped.jpg|A flock displaying their distinctive behaviour of running with the ebb and flow of waves (while feeding). Willapa Bay, near Tokeland, Washington.

File:Sanderlings running in Lima Perú.jpg|A large flock Sanderlings Running in Lima, Peru

File:Sanderling from the Crossley ID Guide Britain and Ireland.jpg|ID composite

</gallery>

Notes

Footnotes

References

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  • Sanderling Species text in The Atlas of Southern African Birds
  • Sanderling Species Account — Cornell Lab of Ornithology
  • Sanderling - Calidris alba — USGS Patuxent Bird Identification InfoCenter