There are over 180 species of marine birds found throughout Europe's seas, and many of these undertake yearly migrations between feeding and breeding grounds. These include waders and waterbirds, such as ducks, geese, swans, divers and grebes; as well as birds that are usually referred to as seabirds: petrels, shearwaters, gannets, cormorants, skuas, gulls, terns and auks.