Arctic tern, sea bird whose migrations are the longest of any bird - from summer breeding areas in the far north to wintering areas in Antarctica, a round trip of about 35,500km. It has grey, black and white feathers and a reddish bill and feet. It nests in colonies and lays 1-4 eggs in a sandy scrape nest. Length: 38cm. Family Laridae; species Sterna paradisaea.