[order] Charadriiformes | [family] Scolopacidae | [latin] Calidris alba | [UK] Sanderling | [FR] Bécasseau sanderling | [DE] Sanderling | [ES] Correlimos tridáctilo | [IT] Piovanello tridattilo | [NL] Drieteenstrandloper

Drieteenstrandloper determination

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The Sanderling is a small, light-colored sandpiper with a straight, black bill and black legs. The male and female look similar. In breeding plumage, it has a rufous head and neck and a rufous wash that extends onto its back. In non-breeding plumage, the adult is white underneath and very pale gray above while the juveniles are white underneath with a dark and light mottled top. Late-molters, Sanderlings don't reach their breeding plumage until late May. This is the only sandpiper that lacks a hind toe, which allows it to be a strong runner.
Sanderlings flock, and members of different flocks interchange freely. The quintessential surf-dodger, the Sanderling is most recognized for its behavior of running down to the water's edge with an outgoing wave, and racing back up the beach to avoid the next incoming wave. Dunlins and Western Sandpipers also do this, so this behavior is not diagnostic. They feed by probing, and leave bands of holes along a beach where they have stuck their beaks into the sand probing for food. They also feed in tire tracks. When roosting, they usually stand on one leg, and if disturbed, they will hop away from the disturbance on one leg.

Sanderlings breed farther north than any of the shorebirds found in Washington, nesting in dry, rocky tundra on the land closest to the North Pole. In winter and during migration, they inhabit broad, coastal beaches with light-colored sand. They can also be found on gravelly and rocky beaches and mudflats, and on top of kelp beds. In the fall, adults dominate the optimal habitats, and juveniles take the remaining spots.

Calidris alba breeds in the high Arctic in northern Greenland and Svalbard, with Europe accounting for less than a quarter of its global breeding range. Its European breeding population is relatively small (<50,000 pairs), but was stable between 1970- 1990. Although the trend of the stronghold population in Greenland during 1990-2000 was unknown, there was no evidence to suggest that the species's status deteriorated since 1990, and the European wintering population increased markedly during this period.
The Canadian Wildlife Service estimates the worldwide population of Sanderlings at 643,000 birds, with 300,000 breeding in North America and the remainder across Eurasia. Although the Sanderling is one of our most common sandpipers and has a worldwide distribution, it has experienced serious declines, as much as 80% of the population since the early 1970s. Sanderlings rely heavily on a small number of staging areas during migration, and destruction of these areas can seriously affect the population. Declines are probably due to disturbance on feeding areas during migration. The populations on the Pacific Coast fluctuate, but Christmas Bird Count data suggest that the wintering population in the Northwest has actually increased in recent years.

Sanderlings dine on a variety of aquatic invertebrates and sometimes carrion. One study identified young razor clams as a major source of food on the Washington coast.

This species has a large range, with an estimated global Extent of Occurrence of 100,000-1,000,000 km². It has a large global population estimated to be 620,000-700,000 individuals (Wetlands International 2002). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern [conservation status from birdlife.org]

Sanderlings nest on the dry, northern tundra, often close to lakes or ponds. The nest is on the ground, often on an elevated spot out in the open. The nest is a shallow scrape lined with leaves. The female generally lays two clutches, and either two males, or one male and the female herself, each incubate a clutch of four eggs. If the female has two males incubating the eggs, she will depart. If she is incubating a clutch, she will stay with the young, which hatch after 24 to 31 days, until they fledge at about 17 days. Males also stay with the young, which leave the nest and can feed themselves immediately after hatching.

Long distance migrant. Seems to be restricted to few stopover sites along flyways. Highly faithful to wintering sites. Migration largely offshore and coastal, but locally frequent inland across Africa and North America. Also occurs on many small oceanic islands. Birds from Greenland and Siberia pass through British Islands, some staying there, but most winter down continental coasts from Europe South to South Africa. Evidently loop migration, as in spring some birds from West Africa cross Sahara to Central Mediterranean. Siberian birds East of Taymyr move down East Russian coast or overland, to Indian Ocean and South West Pacific; in East Asia, common migrant through Korea, East China and Japan, and also through Vietnam and Cambodia. Birds wintering in South East Asia and Australia probably originate from New Siberian Islands. Nearctic birds move along Pacific and Atlantic coasts and via prairies and Texas coast. Most abundant on Pacific coast of South America, whence N orth migration mainly via inland and Atlantic routes. High numbers staging at Delaware Bay, probably mostly from Brazil. Pacific North American winterers migrate along Pacific coast. Many 1-year-olds apparently return to breeding grounds, but some remain South all year.