Curlew Sandpiper

Identification

The curlew sandpiper is a small wader measuring 18–23 cm in length, with a distinctive black bill, dark brown irises, and dark grey to black feet. It displays a large white patch on the rump and, in flight, shows a distinctive white stripe across the wing. The bird undergoes dramatic seasonal plumage changes, moulting yearly to transform between breeding and non-breeding appearances.

In non-breeding plumage, the curlew sandpiper shows greyish-brown upperparts and white underparts with pale streaking, becoming browner as feather wear increases. The breeding plumage is far more striking: the entire front is tinted deep rusty colour, more intensely so in males, with the head and upper back also showing reddish tones. Juveniles resemble non-breeding adults but display creamy-coloured streaking on the breast and pale fringes on wing feathers, creating a scaly appearance. First-year birds occasionally develop breeding plumage with white spots on the chest. In breeding plumage, curlew sandpipers may superficially resemble the larger red knot or red phalarope, while non-breeding birds can be confused with dunlins or stilt sandpipers.

Range & Habitat

This is a long-distance migrant with a remarkable annual cycle. The curlew sandpiper breeds in the bogs and coastal lowlands of the Siberian Arctic, arriving in June and remaining until August or September. After breeding, the population migrates south to winter in Africa and along the coasts of Oceania and southern Eurasia, where they occupy tidal mudflats and saltpans. Notably, first-year birds do not migrate or breed; instead, they remain year-round in their overwintering range.

The species faces significant conservation challenges. Listed as vulnerable on the IUCN Red List, curlew sandpipers have experienced substantial habitat loss at both overwintering and migratory sites due to land development and the invasive smooth cordgrass. Climate change has also negatively impacted breeding productivity. The estimated annual survival rate is 75–80%.

Behaviour & Diet

Curlew sandpipers exhibit complex courtship displays involving multiple distinct behaviours. Males construct faux nests on the ground to present to females, engage in graceful aerial chases accompanied by frequent warbling calls, and perform ground displays where they dance around the female while displaying tail feathers and rump—sometimes culminating in copulation. Females almost always lay a single clutch around the end of June; eggs hatch after 20 days and chicks fully fledge in 14–20 days. Chicks are relatively mature and mobile at birth, an adaptation to their Arctic breeding grounds.

Breeding success is closely linked to the lemming population cycle; in years with abundant lemmings, the birds' predators focus on them instead, improving sandpiper survival rates. The curlew sandpiper is omnivorous and highly social, foraging in large flocks in wetlands for various invertebrates including crabs and insects.

Best Time & Places to See It

To observe curlew sandpipers, time your visit to coincide with migration or wintering periods rather than the Arctic breeding season. The species occupies tidal mudflats and saltpans across Africa, Oceania, and southern Eurasia during winter months. Spring and autumn migrations offer excellent opportunities to see them in coastal wetland habitats along their migration routes. First-year birds, which remain in overwintering ranges year-round, provide opportunities for observation outside migration windows.

Photography Tips

Photograph curlew sandpipers during breeding season visits to the Arctic to capture their striking rusty plumage—particularly in males, whose deep rusty colouration is most intense. The contrast between breeding and non-breeding plumages makes seasonal photography rewarding. The bird's large white rump patch and distinctive wing stripe are prominent field marks worth capturing in flight photography.

During migration and winter, focus on their habit of foraging in large flocks in mudflats and saltpans, which offers opportunities for flock behaviour photography. The white eyebrow stripe, mottled upperparts in non-breeding birds, and scaly appearance of juveniles all provide excellent detail shots. Early morning light on coastal wetlands will best reveal the subtle plumage details that distinguish this species from similar waders.