The skimmers are obviously closely related to the terns, but are easily separated from these by their knife like bills with a extremely elongated lower mandible with which they 'plough' the surface of the water. The three species occur each in a different parts of the world and are unlikely to be confused. The American species is the largest and has black tips to the upper and lower mandible. The other two species have orange bills. Their plumages are very similar: blackish upper parts and white bellies.
- Black Skimmer Rynchops niger. Americas. Three subspecies:
- R. n. niger. Locally along Atlantic coasts of North America south to Brazil.
- R. n. cinerascens. North and Northeast South America, including Amazon Basin
- R. n.intercedens. East and Southeast South America.
- African Skimmer Rynchops flavirostris. Africa, south of Sahara.
- Indian Skimmer Rynchops albicollis. Asia, rivers and lakes of Iran to Indochina.
Black Skimmer Rynchops niger niger. North America
Culmen: 68.9 mm; Total 162 mm