|
The Sandwich tern (''Thalasseus sandvicensis'') is a seabird of the tern family, Sternidae. It is very closely related to the lesser crested tern (''T. bengalensis''), Chinese crested tern (''T. bernsteini''), Cabot's tern (''T. acuflavidus''), and elegant tern (''T. elegans'') and has been known to interbreed with the lesser crested. The Sandwich tern is a medium-large tern with grey upperparts, white underparts, a yellow-tipped black bill and a shaggy black crest which becomes less extensive in winter with a white crown. Young birds bear grey and brown scalloped plumage on their backs and wings. It is a vocal bird. It nests in a ground scrape and lays one to three eggs. Like all ''Thalasseus'' terns, the Sandwich tern feeds by plunge diving for fish, usually in marine environments, and the offering of fish by the male to the female is part of the courtship display. == Taxonomy == The terns, family Sternidae, are small to medium-sized seabirds, gull-like in appearance, but usually with a more delicate, lighter build and shorter, weaker legs. They have long, pointed wings, which gives them a fast buoyant flight, and often a deeply forked tail. Most species are grey above and white below, and have a black cap which is reduced or flecked with white in the winter.〔Snow & Perrins (1998) p.764〕 The Sandwich tern was originally described by ornithologist John Latham in 1787 as ''Sterna sandvicensis'', but was recently moved to its current genus ''Thalasseus'' (Boie, 1822) following mitochondrial DNA studies which confirmed that the three types of head pattern (white crown, black cap, and black cap with a white blaze on the forehead) found amongst the terns corresponded to distinct clades.〔 The current genus name is derived from Greek ''Thalassa'', "sea", and ''sandvicensis'' refers to Sandwich, Kent, Latham's type locality. In birds, the specific name ''sandvicensis'' usually denotes that the species was first described from Hawaii, formerly known as the "Sandwich Islands", but the Sandwich tern does not occur there. This bird has no subspecies. Two former subspecies are now treat as a separate species called the Cabot's tern (''T. acuflavidus''), which breeds on the Atlantic coasts of North America, wintering in the Caribbean and further south, and has wandered to Western Europe. The former species, ''T. s. eurygnatha'' (Saunders 1876), is sometimes treated as a separate species called the Cayenne tern (''T. eurygnatha''), which breeds on the Atlantic coast of South America from Argentina north to the Caribbean, intergrading with ''T. acuflavidus'' in the north of its range. The DNA analysis showed that Cayenne tern differed genetically from ''T. acuflavidus'', but the difference was not sufficient to confirm it as a definite separate species.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sandwich tern」の詳細全文を読む スポンサード リンク
|