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The white-eyed river martin (''Pseudochelidon sirintarae'') is a passerine bird, one of only two members of the river martin subfamily of the swallows. Since it has significant differences from its closest relative, the African river martin, it is sometimes placed in its own genus, ''Eurochelidon''. First found in 1968, it is known only from a single wintering site in Thailand, and may be extinct, since it has not been seen since 1980 despite targeted surveys in Thailand and neighbouring Cambodia. It may possibly still breed in China or Southeast Asia, but a Chinese painting initially thought to depict this species was later reassessed as showing pratincoles. The adult white-eyed river martin is a medium-sized swallow, with mainly glossy greenish-black plumage, a white rump, and a tail which has two elongated slender central tail feathers, each widening to a racket-shape at the tip. It has a white eye ring and a broad, bright greenish-yellow bill. The sexes are similar in appearance, but the juvenile lacks the tail ornaments and is generally browner than the adult. Little is known of the behaviour or breeding habitat of this martin, although like other swallows it feeds on insects caught in flight, and its wide bill suggests that it may take relatively large species. It roosts in reed beds in winter, and may nest in river sandbanks, probably in April or May before the summer rains. It may have been overlooked prior to its discovery because it tended to feed at dawn or dusk rather than during the day. The martin's apparent demise may have been hastened by trapping, loss of habitat and the construction of dams. The winter swallow roosts at the only know location of this martin have greatly reduced in numbers, and birds using river habitats for breeding have declined throughout the region. The white-eyed river martin is one of only two birds endemic to Thailand, and the country's government has noted this through the issues of a stamp and a high-value commemorative coin. ==Taxonomy== Within the swallow family, the white-eyed river martin is one of only two members of the river martin subfamily ''Pseudochelidoninae'', the other being the African river martin ''Pseudochelidon eurystomina'' of the Congo basin in Africa. These two species possess a number of distinctive features which mark them out from other swallows and martins, including their robust legs and feet, and stout bills.〔Turner & Rose (1989) pp. 86–88.〕 The extent of their differences from other swallows and the wide geographical separation of the two martins suggest that they are relict populations of a group of species that diverged from the main swallow lineage early in its evolution.〔 The separation of this subfamily is supported by genetic evidence, and their habit of nesting in burrows is thought to be characteristic of the earliest members of the swallow family. The white-eyed river martin was discovered in 1968 by Thai ornithologist Kitti Thonglongya, who gave the bird its current binomial name.〔〔 The genus name ''Pseudochelidon'' (Hartlaub, 1861) comes from the Ancient Greek prefix ''ψευδο/pseudo'' "false" and ''χελιδον''/''chelidôn'', "swallow", and the species name ''sirintarae'' commemorates Princess Maha Chakri Sirindhorn of Thailand.〔 The African and Asian ''Pseudochelidon'' species differ markedly in the size of their bills and eyes, suggesting that they have different feeding ecologies, with the white-eyed river martin probably able to take much larger prey. The Thai species also has a swollen, hard gape (fleshy interior of the bill) unlike the softer, fleshier, and much less prominent gape of the African river martin.〔 Thonglongya estimated the bill of the Thai species to be 17.6% wider than that of the African bird, but a later estimate, using specimens preserved in alcohol instead of dried skins (to avoid shrinkage), gave a difference of 22.5% between the bills of the two swallows.〔 Following a suggestion by Kitti in his original paper,〔 Richard Brooke proposed in 1972 that the white-eyed river martin was sufficiently different from the African species to be placed in a separate monotypic genus ''Eurochelidon'', but this was contested by other authorities.〔Turner & Rose (1989) pp. 5–6.〕〔 The new genus was not subsequently widely adopted by other authors,〔〔 although BirdLife International uses ''Eurochelidon''.〔(【引用サイトリンク】 publisher =BirdLife International )〕 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「White-eyed river martin」の詳細全文を読む スポンサード リンク
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