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Common Tern | Sterna hirundo
Visdief | Charrán Común
The Common Tern is the most numerous tern along the coasts of southern Africa, but it does not breed here: it comes from Europe and Asia and winters in tens of thousands. Almost all birds are in non-breeding plumage, which makes identification among the other medium-sized terns harder than on the breeding grounds.
Voice
A high, rolling kee-yarr stressed on the second syllable, and a short kik or kirri-kirri in groups. At roosts a constant murmur.
Recording: Lionel FREDERIC — CC BY-NC-SA 4.0 · converted to mono · xeno-canto
Identification
31–35 cm, including tail streamers. In non-breeding plumage a white forehead and forecrown and a black rear crown and nape; the bill is black, sometimes with a little red at the base, the legs dark red. The upperparts are mid-grey, with a dark carpal bar on the forewing. The outer primaries form a dark wedge that becomes more obvious with wear during the summer; from below only the trailing edge of the primaries is broadly dark. Rump and tail are white, and at rest the streamers do not reach beyond the wingtip. Birds in breeding plumage, with a black cap and red bill with a black tip, are mainly seen in March–April. Flight is light with even wingbeats; it fishes by hovering and diving at an angle.
Confusion species
Arctic Tern Sterna paradisaea has a shorter bill, shorter legs, a rounder head and translucent primaries from below with a narrow, sharp black trailing edge; in non-breeding plumage a weaker carpal bar. Antarctic Tern Sterna vittata is in breeding plumage in the southern winter, with a red bill and grey underparts, but is tricky in non-breeding plumage; it is stockier with a heavier bill. Roseate Tern Sterna dougallii is paler, whiter below, with longer streamers and faster, stiffer wingbeats. Sandwich Tern Thalasseus sandvicensis is larger, with a long black bill with a yellow tip.
Habitat
Inshore waters out to a few tens of kilometres, bays, estuaries and lagoons; it roosts and rests on sandbanks, beaches, salt pans and breakwaters. It feeds on small shoaling fish such as anchovy and young sardine, often in mixed flocks with other terns over feeding predatory fish. Inland it is rare on large lakes and dams.
Where the bird is most at home, classified by the vegetation units of southern Africa.
Range and movements
Along the entire coast of the region, from Angola through Namibia and South Africa to Mozambique, with the largest numbers on the west coast and in KwaZulu-Natal. Large roosts are found at Walvis Bay, Saldanha Bay and Langebaan Lagoon and at Richards Bay, among others. Irregular inland, mainly on large reservoirs and Lake Malawi. It breeds in Europe, Asia and North America; Asian birds winter mainly around the Indian Ocean.
- Resident
- Summer visitor (c. Oct–Mar)
- Winter visitor (c. Apr–Sep)
- Passage (Mar–Apr, Oct–Nov)
- dark = core range, pale = thinly spread
How and when to look
The best places are evening roosts on beaches and in estuaries, where thousands of birds come in shortly before sunset. Look carefully at the primaries and bill length to pick out Arctic Terns. Rings are read regularly: part of the birds turn out to come from Finland, the Baltic states and Russia.
Conservation status
Not globally threatened. In the region the main threats are disturbance of roosts by dogs, vehicles and recreation, oil pollution and overfishing of small shoaling fish. Counts at the large roosts have been lower since the 1990s than in the past.
Scientific name
Sterna hirundo | Linnaeus, 1758
Linnaeus described the species in 1758 and placed it straight away in the genus where it still stands. He introduced the genus Sterna in that same work. Sterna goes back to Old English stearn, which appears in the poem The Seafarer; the Frisians used a related word for terns. hirundo is Latin for 'swallow', after the forked tail and light build the tern shares with that bird. The specimen the first description was based on came from Sweden.