Ruff – Calidris pugnax
Ruff is a medium-sized wading bird that breeds in marshes and wet meadows across northern Eurasia. This highly gregarious sandpiper is migratory and sometimes forms huge flocks in its winter grounds, which include southern and western Europe, Africa, southern Asia and Australia. It is usually considered to be the only member of its genus, and the broad-billed and sharp-tailed sandpipers are its closest relatives. The ruff has a distinctive gravy boat appearance, with a small head, medium-length bill, longish neck and pot-bellied body. It has long legs that are variable in colour but usually yellow or orange. In flight, it has a deeper, slower wing stroke than other waders of a similar size, and displays a thin, indistinct white bar on the wing, and white ovals on the sides of the tail.

It sounds like this
Recording by Patrik Åberg from Xeno-canto