The Sanderling (Calidris alba, syn. Crocethia alba or Erolia alba) is a small wader.

Taxonomy:

It is somewhat unlike other sandpipers in appearance, which has led to the suggestion that it should be placed into a monotypic genus Crocethia. A more recent review (Thomas et al., 2004) indicates, however, that the sanderling is a fairly typical "stint" or small sandpiper and should be separated from the large knots with its closest relatives in a distinct genus.

Scientific classification

Kingdom:         Animalia

Phylum:           Chordata

Class:              Aves

Order:              Charadriiformes

Family:             Scolopacidae

Genus:             Calidris

Species:          C. alba

Binomial name: Calidris alba Pallas, 1764 

Distribution:

Sanderlings are found very widely along Australian coastlines and are regular visitors to New Zealand. The species could be considered cosmopolitan, being found along the coastline in many other countries. They breed from north America to north Russia and islands in the Arctic Ocean. It is a circumpolar Arctic breeder, and is a long-distance migrant, wintering south to South America, South Europe, Africa, and Australia. It is highly gregarious in winter, sometimes forming large flocks on coastal mudflats or sandy beaches.

This is a migratory species, breeding mostly in Siberia, moving south with different breeding populations moving to different areas. The Sanderlings migrating to Australia and south-east Asia probably breed on New Siberian Island, leaving mid-July to mid-August and juveniles a little later. They fly in large flocks, flying huge distances without stopping. They arrive in Australia from September and leave the Sydney area by early April. Small numbers over-winter here. 

Physical Characteristics:

An active, pale wader reaching 20 cm long. The non-breeding adult is pale grey above and white below, with a black patch at the angle of the wing. It has a short, straight, broad-based black bill, blackish-brown wings with broad, white wing-stripes, and short, black legs. In flight, it shows the widest white wing-bar of any sandpiper, on a very dark wing. The forehead and eyebrows are white; the rump and tail have a brown centre and white sides. Elements of the rufous breeding plumage may be visible in some birds just after their spring arrival or before their autumn departure, and in some overwintering birds.

In winter plumage their almost white, silvery plumage distinguishes them from both the longer-billed Dunlins and the smaller Little Stints. The contrasting black spot around the shoulder of the wing is another really useful feature. You have to become familiar with the size and shape of a Sanderling to confidently identify the juveniles with their spangled silver and black upperparts and the summer plumaged birds with their reddish upperparts heavily marked with black. In flight the pale wing bar is broader and more contrasting than in similar birds such as Dunlin or the stints.

The Sanderling is a tiny, pale grey wader, seen darting along shorelines. The upper body is grey, with white below. The bill is dark, thick at the base and slightly drooped at the tip. The legs are short and black and lacking a hind toe. The flight is flickering and a prominent white wingbar is obvious. When in breeding plumage, the head, neck and breast is rufous. 

The Sanderling is slightly larger than the Red-necked Stint, C. ruficollis, with a longer, heavier bill, and smaller than the Curlew Sandpiper, C. ferruginea. In flight the large white wingbar is obvious, as is its way of dashing along the beach in front of the waves. 

Habitat:

Sanderlings are found on open sandy beaches at the edge of the waves, on sandbars and spits. They roost on bare sand in the dunes or behind piles of kelp.  Often found in coastal areas on low beaches of firm sand, near reefs and inlets, along tidal mudflats and bare open coastal lagoons; individuals are rarely recorded in near-coastal wetlands. Generally occurs in small flocks, however may associate freely with other waders. Individuals run behind receding waves, darting after insects, larvae and other small invertebrates in the sand, then dart back up the beach as each wave breaks. 

Diet:

A Sanderling will feed busily and briskly on the shoreline, jabbing its bill in the sand, snatching at prey, then retreating from the waves - like a clockwork toy. They eat mainly insects and other arthropods and small crustaceans, by day and night. They also eat seeds and buds on their nesting grounds.  Also feeds on plants, seeds, worms, crustaceans, spiders, jellyfish and fish, foraging around rotting heaps of kelp, at the edges of shallow pools on sandpits and on nearby mudflats. 

Behavior:

Sanderling behavior is distinctive, but visually, if the size is misjudged, a breeding plumage sanderling can be mistaken for some varieties of stint, or a winter plumage sanderling can be mistaken for a Dunlin or Red Knot. It can be told from other small wading birds, given good views, by its lack of a hind toe. Roosts on bare sand, behind clumps of beach-cast kelp or in coastal dunes. 

Breeding:

Sanderlings breed in the high Arctic tundra so the breeding season is short, lasting about eight weeks. They may even lay two clutches in North Canada, one incubated by the male and one by the female. Generally, pairs share incubation, in a shallow nest which is usually unlined and in an exposed position.