The green sandpiper (Tringa ochropus) is a small wader (shorebird) of the Old World. The green sandpiper breeds across subarctic Europe and east across the Palearctic and is a migratory bird, wintering in southern Europe, the Indian Subcontinent, Southeast Asia, and tropical Africa. Food is small invertebrate items picked off the mud as this species works steadily around the edges of its chosen pond.
This is not a gregarious species, although sometimes small numbers congregate in suitable feeding areas. Green sandpiper is very much a bird of freshwater, and is often found in sites too restricted for other waders, which tend to like a clear all-round view.
Source : wikipedia