The osprey (Pandion haliaetus), also called sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor, reaching more than 60 cm (24 in) in length and 180 cm (71 in) across the wings. It is brown on the upperparts and predominantly greyish on the head and underparts.

The genus name Pandion derives from Pandíōn Πανδίων, the mythical Greek king of Athens and grandfather of Theseus, Pandion II. The species name haliaetus comes from Greek ἁλιάετος haliáetos “sea-eagle”.

The osprey tolerates a wide variety of habitats, nesting in any location near a body of water providing an adequate food supply. It is found on all continents except Antarctica, although in South America it occurs only as a non-breeding migrant.

As its other common names suggest, the osprey’s diet consists almost exclusively of fish. It possesses specialised physical characteristics and unique behaviour in hunting its prey. Its unique characteristics classify it in its own taxonomic genus, Pandion, and family, Pandionidae.

The osprey has several adaptations that suit its piscivorous lifestyle:

• reversible outer toes
• sharp spicules on the underside of the toes
• closable nostrils to keep out water during dives
• backward-facing scales on the talons which act as barbs to help hold its catch
• dense plumage which is oily and prevents its feathers from getting waterlogged.