Arctic Tern bird is essentially similar to Common Tern, but smaller bodied and longer tailed, and is 15-20 per cent lighter than that species. Arctic Tern bird is short-legged and short-necked, the short bill is blood-red, and the tail extends beyond the wingtips at rest. In flight the upperwing shows cleaner-looking primaries, with a narrow, dusky trailing edge to the outer primaries, and the underwing shows a neat, narrow black trailing edge to the outer primaries. The underparts are washed grey, contrasting subtly with the white cheeks and chin.
Arctic Tern bird is a summer visitor to higher latitudes than any other of our terns, it typically nests colonially and in the north of its range these colonies can be very large. Almost always found nesting close to the coast, on inshore islets and islands, shingle beaches, rocky shores, pastures, sedge moor and coastal meadows. In northern Scandinavia, however, Arctic Tern bird also nests far inland along rivers on islands and banks. Outside the breeding season it can be found migrating along the coasts of our region, occasionally visiting inland water bodies when weather conditions funnel migrants overland. It ha; possibly the longest migration of any bird, wintering in Antarctica.
Arctic tern bird is a similar range of notes to Common Tern, but noticeably different, being higher pitched, shrill rather than harsh, and with a drier quality. Very vocal and noisy around the breeding grounds, a commonly heard call is a sharp "kik", often repeated. Arctic Tern bird also gives a high-pitched piping "ki'ki'ki'ki'ki" or "i'i'i'i'i'i'i", and a longer cry similar to that of Common Tern but harder and drier with the emphasis on the first syllable, as in "wheeer'i", "keeee'rr" or "krri-errrrr". Variants include "eeeerr'eeeeerr", a harsh "eeerri'eeerri" and a scolding "i'i'i'i'i'irrr". Also makes a hard dry "kt'kt'kt'kt" and a high whistled "peee-peee-peee". Juveniles also make a high, plaintive "peee".