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Arctic Tern | Sterna paradisaea
Noordse stern | Charrán ártico
The Arctic Tern makes the longest migration of any bird, from Arctic and northern temperate breeding grounds to the seas around Antarctica and back. Most of the route crosses the open Atlantic, far east of the Antilles, so in the Caribbean it is only a very rare visitor. Most records involve young birds on migration.
Voice
Usually silent at sea. Gives a high, piercing kee-ar stressed on the second syllable, and short kip calls. The calls are shorter and higher than those of Common Tern.
Recording: Stanislas Wroza — CC BY-NC-SA 4.0 · shortened to the first 60 s, mono · xeno-canto
Identification
33–36 cm, including the tail streamers. Very similar to Common Tern, but with a rounder head, a shorter bill and very short legs, so that a perched bird sits low. Breeding adults have an all-red bill without a black tip, a black cap, grey underparts with a white cheek stripe and long tail streamers that project beyond the wing tips at rest. In flight all primaries are translucent from below, with a narrow, sharply defined black trailing edge. Non-breeding birds and juveniles have a white forehead and underparts and a dark bill; juveniles show a weak dark carpal bar and white secondaries forming a pale trailing edge to the wing.
Confusion species
Common Tern Sterna hirundo has a longer, black-tipped bill, longer legs and a broad, blurred dark trailing edge under the primaries, with only the inner primaries translucent; juvenile Common Terns have a dark carpal bar and greyer secondaries. Roseate Tern Sterna dougallii is paler, with white underparts and a dark bill. Forster's Tern Sterna forsteri has silvery-white primaries and a black eye mask outside the breeding season.
Habitat
Open sea, sometimes closer inshore off headlands and in bays, especially after storms. It fishes by plunge-diving from a few metres up, often after a short hover.
Where the bird is most at home, classified by the vegetation types of the Caribbean.
Range and movements
Only a handful of confirmed records, scattered across the region, including from the Bahamas, Puerto Rico and the Lesser Antilles. Given its route over open water and its similarity to Common Tern, it is probably under-recorded. Beyond the region it breeds circumpolarly in northern North America, Greenland, Iceland and northern Eurasia, in America south to Massachusetts, and winters in the Southern Ocean.
How and when to look
Seawatching from headlands and pelagic trips during migration offer the best chances. With any short-legged tern showing translucent primaries, the trailing edge of the wing and the bill length deserve close attention; a photo of the underwing is often decisive.
Conservation status
Not threatened globally. In parts of the breeding range numbers are falling through food shortage and predation at colonies. In the Caribbean a very rare visitor with no established population.
Scientific name
Sterna paradisaea | Pontoppidan, 1763
Pontoppidan described the species in 1763 and placed it straight away in the genus where it still stands. The genus Sterna was introduced in 1758 by Linnaeus. Sterna goes back to Old English stearn, which appears in the poem The Seafarer; the Frisians used a related word for terns. paradisaea is Late Latin for 'of paradise', from paradisus 'paradise'. The specimen the first description was based on came from Christiansø, Denmark.