Tern make up the clutch. Most species feed on fish caught by diving from flight, but the marsh terns are insect-eaters, and some large terns will supplement their diet with small land vertebrates. Many terns are long-distance migrants, and the Arctic tern may see more daylight in a year than any other animal. Terns are long-lived birds and are relatively free from natural predators and parasites; most species are declining in numbers due directly or indirectly to human activities, including habitat loss, pollution, disturbance, and predation by introduced mammals. The Chinese crested tern is in a critical situation and three other
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