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
Arctic tern of its range. The Arctic tern was known as sea swallow describing their slender shape as they swoop over the water. The genus name "Sterna" is derived from Old English "stearn", "tern". The specific "paradisaea" is from Late Latin "paradisus", "paradise". The Scots names "picktarnie", "tarrock" and their many variants are also believed to be onomatopoeic, derived from the distinctive call. Due to the difficulty in distinguishing the two species, all the informal common names are shared with the common tern. The Arctic tern has a continuous worldwide circumpolar breeding distribution; there are no recognized subspecies. It can be found