All species › Waders, gulls and terns › Skimmers, noddies, terns and gulls › South American Tern
South American Tern | Sterna hirundinacea
Zuid-Amerikaanse visdief | Gaviotín sudamericano | Trinta-réis-de-bico-vermelho
The South American Tern is a robust, red-billed tern of the coasts of southern South America, from Peru and Brazil to Tierra del Fuego. It breeds in colonies on rocks and islands and in the guide area feeds in the cool waters of the Humboldt Current. Along the coast of Peru it is present year-round; it sometimes wanders north to Ecuador.
Voice
A shrill kee-yerr and a short kip, somewhat lower and harsher than in Common Tern; constant screeching in the colony.
Recording: JAYRSON ARAUJO DE OLIVEIRA — CC BY-NC-SA 4.0 · xeno-canto
Identification
41–43 cm, a robust tern with a fairly heavy, slightly decurved red bill, red legs and a deeply forked tail with long outer feathers. In breeding plumage the cap is black and the cheeks white, and the rest of the body is pale blue-grey, with a grey wash over the underparts; the outer primaries have dark outer webs. Outside the breeding season the forehead is white or speckled white, with a black hindcrown, and the bill is duller red, sometimes with a dark tip. Juveniles have dark brown barring on the mantle and wing coverts, a dark crown and a blackish bill. The sexes are alike.
Confusion species
Common Tern Sterna hirundo is smaller, with a thinner bill that has a black tip in breeding plumage, and in non-breeding plumage a dark bar on the forewing and a black bill. Arctic Tern Sterna paradisaea is smaller, with a shorter bill, very short legs and translucent primaries. Royal Tern Thalasseus maximus is larger, with an orange bill and a crest. Inca Tern Larosterna inca is dark slate grey with white, curled moustache plumes.
Habitat
Rocky and sandy coasts, islands, bays and river mouths; it forages close inshore over cool sea water, where it dives from some height for small schooling fish such as anchovies. It breeds in colonies on rocks, cliffs and islands; the nest is a scrape in the ground or among stones.
Where the bird is most at home, classified by the vegetation units of the Andes and the west coast.
Range and movements
In Peru along the whole coast and on the coastal islands; breeds locally. In Ecuador a rare visitor along the coast, mainly in the southern winter. Absent from Colombia, Bolivia and the Galápagos. Outside the guide area along the coast of Chile and from south-eastern Brazil through Uruguay and Argentina to Tierra del Fuego and the Falkland Islands; outside the breeding season birds wander north along both coasts.
- Resident
- dark = core range, pale = thinly spread
How and when to look
Along the coast of central and southern Peru, for example around the Paracas Peninsula, birds often sit on rocks and piers among other seabirds; there you can compare them with Common and Inca Terns.
Conservation status
Least Concern. Colonies are sensitive to disturbance and egg collecting, and breeding success drops in El Niño years when fish stocks collapse.
Scientific name
Sterna hirundinacea | Lesson, 1831
Lesson described the species in 1831 and placed it straight away in the genus where it still stands. The genus Sterna was introduced in 1758 by Linnaeus. The genus name comes from Old English stearn, a word for a tern; the Frisians had a similar word. The species name comes from Latin hirundo, 'swallow', with -aceus, 'resembling'. The specimen the first description was based on came from Santa Catarina, Brazil.