The Arctic Tern (Sterna paradisaea) is a seabird of the tern family Sternidae. The call is a clear piping, similar to that of the Common Tern, but higher pitched and more strident.
This bird has a circumpolar distribution and can be found in abundance throughout the arctic and sub-arctic regions of Europe, Asia and North America as far south as Brittany and Massachusetts.
The Arctic Tern is strongly migratory, spending its winters in the Antarctic. This 12,000 mile (19,000 km) journey ensures that this bird sees more daylight than any other creature on the planet. One particularly spectacular example involved an Arctic Tern ringed as a chick not yet able to fly, on the Farne Islands off the Northumberland coast in eastern Britain in summer 1982, which reached Melbourne, Australia in October 1982, a sea journey of over 22,000 km (14,000 miles) in just three months from fledging. The average Arctic Tern in its life will travel a distance equal to going to the moon and back.
The Arctic Tern breeds in colonies on coasts, islands and occasionally inland on tundra near water. It lays up to four eggs. Being the most aggressive tern, it will fiercely defend its nest and young, and will attack humans and other large predators, usually striking the top or back of the head. Although it is too small to cause serious injury it is capable of drawing blood. In this it differs from the Common Tern, which usually veers off at the last moment, relying on bluff to deter predators without actually striking. Other birds can benefit from nesting in an area defended by the Arctic Tern.
Like all Sterna, the Arctic Tern catches fish by means of plunge-diving, usually from the sea, though occasionally it will also fish in coastal freshwater lagoons. It often dives from a “stepped-hover”. The offering of fish by the male to the female is part of the courtship display.
This is a medium-sized tern measuring 33-39cm long and with a wingspan of 66-77cm. It is easily confused within its range with the similar Common Tern Sterna (hirundo) and Roseate Tern Sterna (dougalli). Unlike these two, its thin sharp bill is entirely dark red, as are its short legs. Its upperwings are uniformly grey. Its long tail extends beyond the wingtips on the standing bird, unlike Common Tern, but is shorter than that of Roseate Tern. It is not as pale as Roseate Tern, and has longer wings.
During the winter, Arctic Tern also has to be distinguished from the Antarctic Tern (Sterna vittata) and Kerguelen Tern (Sterna virgata); the six-month difference in moult is the best clue here, with Arctic Terns being in winter plumage during the southern summer.
In winter, the forehead and underparts are white. Juvenile Arctic Terns lack the extensive ginger coloration of young Common Terns and the scaly appearance of juvenile Roseate Terns.