The curlew sandpiper is a small wader that breeds on the tundra of Arctic Siberia. It is strongly migratory, wintering mainly in Africa, but also in south and southeast Asia and in Australasia. It is a vagrant to North America.
These birds are small waders, only slightly larger than dunlin at 21 cm in length, but differ from Dunlin in having a longer down-curved bill, longer neck and legs and a white rump. The breeding adult has patterned dark grey upperparts and brick-red underparts. In winter, this bird is pale grey above and white below, and shows an obvious white supercilium. Juveniles have a grey and brown back, a white belly and a peach-coloured breast.