The marsh sandpiper is a rather small shank, and breeds in open grassy steppe and taiga wetlands from easternmost Europe to central Asia. It resembles a small elegant greenshank, with a long fine bill and very long yellowish legs. Like the greenshank, it is greyish brown in breeding plumage, paler in winter, and has a white wedge up its back that is visible in flight. The length is 10.2 in, wingspan is 23 in and weight is 120 g.
It is a migratory species, with majority of birds wintering in Africa, and India with fewer migrating to Southeast Asia and Australia. They prefer to winter on fresh water wetlands such as swamps and lakes and are usually seen singly or in small groups.