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Arctic Tern | Sterna paradisaea
Noordse stern | Charrán Ártico
The Arctic Tern makes the longest annual migration of any animal: from its breeding grounds around the North Pole to the Antarctic pack ice and back. Large numbers pass the coast of southern Africa, mostly far offshore; on land it is mainly exhausted or immature birds that roost among Common Terns.
Voice
A high, drawn-out and clipped kriii-ah, higher and sharper than that of Common Tern, and a dry rattling kt-kt-kt when excited; rarely heard in the region.
Recording: Stanislas Wroza — CC BY-NC-SA 4.0 · shortened to the first 60 s, mono · xeno-canto
Identification
About 35 cm, slender, with a small round head, a short bill, very short red legs and long tail streamers. In the plumage most birds here wear the forehead is white, the hind crown black and the bill dark; in March and April adults appear in breeding plumage with a full black cap, blood-red bill and grey underparts that set off a white cheek stripe. In flight all the primaries are translucent from below, with only a narrow, sharp black trailing edge; the wings are set well back on the body. Immatures have a whiter inner wing and a less dark leading edge than young Common Terns.
Confusion species
Common Tern (Sterna hirundo) has a longer bill, longer legs and a flatter crown; from below only the inner primaries are translucent and the black trailing edge is broader and more diffuse. Antarctic Tern (Sterna vittata) is in breeding plumage here in winter, with red bill and legs, and is more heavily built. Roseate Tern (Sterna dougallii) is paler, with a longer black bill and very long white tail streamers.
Habitat
Mainly open sea over the continental shelf and beyond, where birds pass in flocks and feed over fish shoals. On land on sandy beaches, rocky shores and lagoons, usually among Common Terns; very rarely inland.
Where the bird is most at home, classified by the vegetation units of southern Africa.
Range and movements
Passes along the entire west coast, from Angola through Namibia to the Western Cape, and to a lesser extent along the south and east coasts; most birds stay out of sight of land. Scattered records inland, mainly after severe storms. Breeds around the North Pole in Europe, Asia and North America and spends the northern winter in the waters around Antarctica.
- Resident
- Passage (Mar–Apr, Oct–Nov)
- dark = core range, pale = thinly spread
How and when to look
Pelagic trips from Cape Town and Walvis Bay in October and November or in March and April often produce flocks. From the shore it is best seen in strong westerly winds from a projecting headland, or at Common Tern roosts, where a single Arctic Tern stands out by its short legs and small round head.
Conservation status
Not threatened. The world population exceeds a million birds, but numbers are falling in parts of the breeding range due to food shortage, changes in ocean climate and predation. For its long migration the species depends on rich feeding areas along the way, such as the cold Benguela Current.
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.