All species › Waders, gulls and terns › Gulls and terns › Yellow-billed Tern
Yellow-billed Tern | Sternula superciliaris
Amazonestern | Charrancito amazónico
The Yellow-billed Tern is a small tern of South American rivers and lakes, where it breeds on sandbars in the large rivers. Outside the breeding season some birds move to coastal lagoons and river mouths. In the Caribbean it is a rare visitor from the nearby mainland, almost only on Trinidad.
Voice
High, short keek calls and a fast, chattering kee-kee-kee, similar to Least Tern.
Recording: Jacob Wijpkema — CC BY-NC-SA 4.0 · converted to mono · xeno-canto
Identification
23–25 cm, small and compact. In breeding plumage a black cap with a white forehead triangle and a black eyestripe, pale grey upperparts and white underparts. The bill is fairly long and stout and entirely yellow, without a black tip; the legs are yellow. The outer primaries form a dark wedge at the wingtip. In non-breeding plumage the crown is white with dark streaks and the bill stays mostly yellow. Juveniles have brown-scaled upperparts and a dull yellow bill with a dark tip.
Confusion species
Least Tern Sternula antillarum is slightly smaller and has a slimmer bill with a black tip; in non-breeding and juvenile plumage that bill is largely black. The Yellow-billed Tern's bill is clearly thicker and almost always yellow. Common Tern Sterna hirundo is much larger, with a red or black bill and long tail streamers.
Habitat
In the breeding range, large rivers with sandbars and lakes; outside the breeding season also river mouths, coastal lagoons, mudflats and rice fields. It fishes by hovering over the water and plunging in.
Where the bird is most at home, classified by the vegetation types of the Caribbean.
Range and movements
Seen several times on Trinidad, mainly on the west coast and at lagoons and rice fields inland; no other reliable records in the region. Beyond the region in South America east of the Andes, from Colombia and Venezuela to northern Argentina and Uruguay.
How and when to look
With flocks of small terns on the west coast of Trinidad, bill colour and thickness are worth checking. An entirely yellow, stout bill outside the Least Tern's breeding season points to this species.
Conservation status
Not threatened. The species is widespread along South American rivers. Dams, fluctuating water levels and disturbance of sandbars can reduce breeding success locally. In the Caribbean a rare visitor with no regular presence.
Scientific name
Sternula superciliaris | (Vieillot, 1819)
Vieillot described the species in 1819 as Sterna superciliaris; because it was later moved to another genus, the author and year stand in brackets. The genus Sternula was introduced in 1822 by Boie. Sternula is a Latin diminutive of Sterna and so means 'little tern'. superciliaris is Latin for 'eyebrowed', after the white above the eye beside the black cap. The specimen the first description was based on came from Paraguay.