Tern sea terns have light grey or white body plumage as adults, with a black cap to the head. The legs and bill are various combinations of red, orange, yellow, or black depending on species. The pale plumage is conspicuous from a distance at sea, and may attract other birds to a good feeding area for these fish-eating species. When seen against the sky, the white underparts also help to hide the hunting bird from its intended prey. The Inca tern has mainly dark plumage, and three species that mainly eat insects, the black tern, white-winged tern, and black-bellied tern, have
Royal tern DNA sequences shows the West African royal tern is closer to the lesser crested tern ("Thalasseus bengalensis") than royal terns on the other side of the Atlantic. This is a large tern, second only to Caspian tern but is unlikely to be confused with the carrot-billed giant, which has extensive dark under wing patches. The royal tern has an orange-red bill, pale grey upper parts and white under parts. Its legs are black. In winter, the black cap becomes patchy. Juvenile royal terns are similar to non-breeding adults. Differences include juveniles having black splotched wings and a yellower bill. An