Sterna anaethetus
The specific name of the bridled tern, anathetus, is derived from the Greek for senseless or stupid, a reference to the ease with which hungry sailors captured this relatively docile seabird. Relative to other terns, the bridled tern is of average size, with a deeply-forked tail and long narrow wings. During the breeding season, the upperparts of its plumage, including the back, wings and tail, are brownish grey, while the underparts are generally whitish. The crown and nape are black but the forehead is marked by a triangular white patch that extends above and behind the eyes. The bill is about as long as the head and is black in colour, as are the legs and feet. Outside of the breeding season, the bridled tern is slightly paler, with its black crown streaked white and brown, and the dark feathers of the upperparts having white-tips, giving it a peppered appearance. Juveniles are similar in appearance to the adults but have a paler, streaked crown and upperparts heavily scaled with white and buff. Four to six subspecies, differing only slightly in appearance but occupying different parts of the bridled tern’s overall range, are variably recognised.
Not Threatened.
The specific name of the bridled tern, anathetus, is derived from the Greek for senseless or stupid, a reference to the ease with which hungry sailors captured this relatively docile seabird. Relative to other terns, the bridled tern is of average size, with a deeply-forked tail and long narrow wings. During the breeding season, the upperparts of its plumage, including the back, wings and tail, are brownish grey, while the underparts are generally whitish. The crown and nape are black but the forehead is marked by a triangular white patch that extends above and behind the eyes. The bill is about as long as the head and is black in colour, as are the legs and feet. Outside of the breeding season, the bridled tern is slightly paler, with its black crown streaked white and brown, and the dark feathers of the upperparts having white-tips, giving it a peppered appearance. Juveniles are similar in appearance to the adults but have a paler, streaked crown and upperparts heavily scaled with white and buff. Four to six subspecies, differing only slightly in appearance but occupying different parts of the bridled tern’s overall range, are variably recognised.
33-38 cm, 95-150 g, wingspan 76-81 cm
Taxonomy:
- Sterna Anaethetus Scopoli, 1786, Panay, Philippines. Formerly united with S. fuscata and S. lunata in separate genus Haliplana or Onychoprion. Geographical variation subtle, and subspecific divisions probably exaggerated; taxonomy in need of revision; validity of forms named as novaehollandiae (Queensland to S Australia) and rogersi (N Western Australia) requires further study. Six subspecies currently recognized. (source: Handbook of the Birds of World)
Subspecies and Distribution:
- * melanoptera Swainson, 1837 - W Africa. * fuligula Lichtenstein, 1844 - Red Sea and E Africa through Persian Gulf and Arabian Sea to W India. * antarctica Lesson, 1831 - Madagascar, Aldabra, Seychelles and Mascarenes through Maldives to Andaman Is. * anaethetus Scopoli, 1786 - extreme S Japan (S Ryukyu Is) and Taiwan S through Philippines and Indonesia to Australia, including Lord Howe I and Norfolk I. * nelsoni Ridgway, 1919 - W coast of Mexico and Central America. * recognita (Mathews, 1912) - West Indies, Belize and islands off N Venezuela.
The bridled tern breeds on coral, rock, or sandy shorelines, and forages over inshore waters and up to 50 kilometres offshore.
It feeds mainly on surface-schooling fish, which it catches by diving head first into the water, or by swooping low over the sea to collect prey from the surface. As an alternative it will rest on the surface and catch fish merely by dipping its head or bill into the water. Aside from fish, the bridled tern also takes small amounts of squid and crustaceans, and occasionally aquatic insects.
The timing of the breeding season varies geographically, but most populations breed in small groups ranging in size from 2 to 30 pairs, but sometimes comprising several hundred. The nests are often distributed in vegetation, rock or rubble, where they can be concealed to reduce the chances of predation. Each breeding pair produces just a single egg which is incubated for 28 to 30 days before hatching. The young fledge when around 50 to 65 days old, but remain dependent on the parent birds for another 30 to 35 days.