HomeGlossary Bird topography Eye-ring A ring of contrasting feathers or bare skin around the eye. A complete versus a broken eye-ring separates several flycatchers and vireos. Bird topographyRelated termsFull glossary Speculum A bright, often iridescent patch on the secondaries of many ducks. Tarsus The lower, usually bare, part of the leg above the toes. Culmen The upper ridge of the bill from its tip to where the feathers begin. Coverts Small feathers that overlap the bases of the flight and tail feathers, on both upper and under surfaces. Primaries The outermost flight feathers of the wing, attached to the "hand"; they provide most of the forward thrust. Cere The bare, often coloured skin at the base of the upper bill in raptors, parrots and pigeons.
Coverts Small feathers that overlap the bases of the flight and tail feathers, on both upper and under surfaces.
Primaries The outermost flight feathers of the wing, attached to the "hand"; they provide most of the forward thrust.