Sanderling
Calidris alba
三趾滨鹬
Introduction
It breeds on Arctic coastal tundra north of the 5°C July isotherm. Its winter distribution extends across marine coasts of South America, Europe, Africa, and Australia. It forms single-species flocks of hundreds to thousands of individuals. The species employs a distinctive feeding behavior involving running along the water's edge to probe sand as waves retreat.
Description
This is a small, plump sandpiper measuring 18–20 centimeters in length and weighing 40–100 grams. Its build is somewhat stouter than other small sandpipers, with a notably thick bill. The winter adult is remarkably pale—almost entirely white apart from a dark shoulder patch—which inspired its scientific name meaning 'white.' In summer breeding plumage, the face and throat become a striking brick-red color. Juveniles display a spangled black-and-white pattern with much higher contrast than adults. Unlike most other small sandpipers, this species completely lacks a hind toe, a distinctive anatomical feature.
Identification
This species can be identified by its unique combination of features: a stout build, thick bill, and distinctive 'bicycling' running action along sandy beaches as waves retreat and advance. The strong white wingbar is visible in flight. Birdwatchers should note the complete absence of a hind toe, which separates it from other small sandpipers. In breeding plumage, it may be confused with certain stints, while winter plumage can resemble dunlin or red knot. However, its pale winter plumage, stouter build, and lack of hind toe distinguish it from these lookalikes. Good views reveal its behavioral uniqueness—the characteristic running pattern at the water's edge.
Distribution & Habitat
This species breeds across the High Arctic regions of North America, Europe, and Asia, including the Canadian Arctic Archipelago, Nunavut, Greenland, Alaska, Spitsbergen, and northern Russia from the Taymyr Peninsula to the New Siberian Islands. During winter, it has an almost worldwide distribution along marine coasts. It is a complete migrant, traveling 3,000 to 10,000 kilometers between breeding and wintering sites. Adults leave the breeding grounds in July and early August, while juveniles depart in late August and September. The northward migration begins in March. Breeding habitat consists of coastal tundra north of the 5°C July isotherm, typically on dry stony areas near wetlands from 60 to 800 meters elevation. Wintering and migration habitats include sandy beaches, tidal mud flats, sand flats, and occasionally rocky shores.
Behavior & Ecology
These birds feed by plunging their bills into the sand to catch small invertebrates burrowing in the upper intertidal zone. Their primary prey includes isopods and mole crabs; bills can penetrate only 2–3 centimeters into sand. The birds employ a frantic running pattern at the water's edge, maximizing prey capture opportunities when invertebrates are most vulnerable near the surface. In spring, birds migrating through Delaware Bay consume large quantities of horseshoe crab eggs. Breeding birds arrive on Arctic grounds in late May or early June. They are territorial, with males defending nesting areas. Breeding strategies include both monogamous pairs and polyandrous arrangements (one female with two males). The female lays 3–4 eggs in a ground scrape from mid June to mid July. On the breeding grounds, diet shifts to insects and some plant material.
Conservation
This species is protected under the Agreement on the Conservation of African-Eurasian Migratory Waterbirds. A significant mortality event was documented in 2024 along the Atlantic coast of the United States, particularly in Virginia, caused by the clade 2.3.4.4b highly pathogenic avian influenza H5N1. Infected individuals displayed severe lesions in the brain and pancreas, leading to rapid death. This event represents one of the few detailed records of avian influenza pathology in migratory shorebirds, highlighting disease risks for this long-distance migrant.
Source: Wikipedia · CC BY-SA 3.0
Taxonomy
- Order
- Charadriiformes
- Family
- Scolopacidae
- Genus
- Calidris
- eBird Code
- sander
Vocalizations
Subspecies (2)
-
Calidris alba alba
breeds far northern Canada (Ellesmere Island), Greenland, and Svalbard eastward at least to Severnaya Zemlya Islands and the Taymyr Peninsula; winters on coasts of western and southern Europe, Africa, and southern Asia eastward to Australasia and some tropical Pacific islands
-
Calidris alba rubida
breeds in northern Alaska and northern Canada (except Ellesmere Island) (populations in eastern Siberia in the Lena Delta and the New Siberian Islands possibly also this subspecies); winters coasts of North and South America (northward to southern British Columbia and southern Maine)
Data Sources
Species description from Wikipedia, licensed under CC BY-SA 3.0.
Bird images and sounds sourced from GBIF, contributed by citizen scientists worldwide under Creative Commons licenses.
Taxonomy data from AviList 2025.