The Ruff (Philomachus pugnax), is a medium-sized wading bird. It is usually considered the only member of its genus Philomachus, but more recent research indicates that the Broad-billed and Sharp-tailed Sandpiper may belong there too. Their breeding habitat is bogs, marshes and wet meadows with short vegetation in northern Europe and Russia. The Ruff is migratory, wintering in southern and Western Europe, Africa and India. They are highly gregarious, with a wintering flock of 1 million birds reported in Senegal. This species is a rare migrant to North America, but has nested in Alaska.

These birds nest in a well-hidden location on the ground, laying 3-4 eggs. The males display at a lek* during the breeding season, standing erect, crouching or taking a variety of postures with the ruff erected. They may jump into the air. They are silent while displaying and when not breeding. These birds forage in wet grassland and soft mud, probing or picking up food by sight. They mainly eat insects and earthworms.

* A lek is a gathering of males, of certain animal species, for the purposes of competitive mating display.