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The barn owl (''Tyto alba'') is the most widely distributed species of owl, and one of the most widespread of all birds. It is also referred to as the common barn owl, to distinguish it from other species in its family, Tytonidae, which forms one of the two main lineages of living owls, the other being the typical owls (Strigidae). The barn owl is found almost everywhere in the world except polar and desert regions, Asia north of the Himalayas, most of Indonesia and some Pacific islands.〔Bruce (1999) pp. 34–75〕 Phylogenetic evidence shows that there are at least three major lineages of barn owl, one in Eurasia and Africa, one in Australasia and one in the New World, and some highly divergent taxa on islands. Some authorities further split the group, recognising up to five species, and further research needs to be done to clarify the position. There is a considerable variation between the sizes and colour of the approximately 28 subspecies but most are between in length with wingspans ranging from . The plumage on head and back is a mottled shade of grey or brown, the underparts vary from white to brown and are sometimes speckled with dark markings. The face is characteristically heart-shaped and is white in most species. This owl does not hoot, but utters an eerie, drawn-out shriek. The barn owl is nocturnal over most of its range but in Britain and some Pacific islands, it also hunts by day. Barn owls specialise in hunting animals on the ground and nearly all of their food consists of small mammals which they locate by sound, their hearing being very acute. They mate for life unless one of the pair gets killed, when a new pair bond may be formed. Breeding takes place at varying times of year according to locality, with a clutch, averaging about four eggs, being laid in a nest in a hollow tree, old building or fissure in a cliff. The female does all the incubation, and she and the young chicks are reliant on the male for food. When large numbers of small prey are readily available, barn owl populations can expand rapidly, and globally the bird is considered to be of least conservation concern. Some subspecies with restricted ranges are more threatened. ==Taxonomy and etymology== The barn owl was one of several species of bird first described in 1769 by the Tyrolean physician and naturalist Giovanni Antonio Scopoli in his '' Anni Historico-Naturales''. He gave it the scientific name ''Strix alba''. As more species of owl were described, the genus name ''Strix'' came to be used solely for the wood owls in the typical owl family Strigidae, and the barn owl became ''Tyto alba'' in the barn owl family Tytonidae. The name literally means "white owl", from the onomatopoeic Ancient Greek ''tyto'' (τυτώ) for an owl – compare English "hooter" – and Latin ''alba'', "white".〔Bruce (1999) pp. 34–75〕 The bird is known by many common names which refer to its appearance, call, habitat, or its eerie, silent flight: white owl, silver owl, demon owl, ghost owl, death owl, night owl, rat owl, church owl, cave owl, stone owl, monkey-faced owl, hissing owl, hobgoblin or hobby owl, dobby owl, white-breasted owl, golden owl, scritch owl, screech owl, straw owl, barnyard owl, and delicate owl.〔Bruce (1999) pp. 34–75〕 "Golden owl" might also refer to the related golden masked owl (''T. aurantia''). "Hissing owl" and, particularly in the US and in India, "screech owl", refers to the piercing calls of these birds. The latter name is more correctly applied to a different group of birds, the screech-owls in the genus ''Megascops''.〔Bruce (1999) pp. 34–75〕 The ashy-faced owl (''T. glaucops'') was for some time included in ''T. alba'', and by some authors its populations from the Lesser Antilles still are. Based on DNA evidence, König, Weick & Becking (2009) recognised the American Barn Owl (''T. furcata'') and the Curaçao Barn Owl (''T. bargei'') as separate species. They also proposed that ''T. a. delicatula'' should be split off as a separate species, to be known as the eastern barn owl, which would include the subspecies ''T. d. sumbaensis'', ''T. d. meeki'', ''T. d. crassirostris'' and ''T. d. interposita''. However, the International Ornithological Committee has doubts about this and states that the split of ''Tyto delicatula'' from ''T. alba'' "may need to be revisited". Some island subspecies are occasionally treated as distinct species, a move which should await further research into barn owl phylogeography. According to Bruce in the ''Handbook of Birds of the World, Volume 5: Barn-owls to Hummingbirds'', "a review of the whole group () long overdue".〔Bruce (1999) pp. 34–75〕 Molecular analysis of mitochondrial DNA shows a separation of the species into two clades, an Old World ''alba'' and a New World ''furcata'', but this study did not include ''T. a. delicatula'' which the authors seem to have accepted as a separate species. A high amount of genetic variation was also found between the Indonesian ''T. a. stertens'' and other members of the ''alba'' clade. The barn owl has a wider distribution than any other species of owl. Many subspecies have been proposed over the years but several are generally considered to be intergrades between more distinct populations. Twenty to thirty are usually recognised, varying mainly in body proportions, size and colour. Island forms are mostly smaller than mainland ones, and those inhabiting forests have darker plumage and shorter wings than those occurring in open grasslands.〔Taylor (2004) p. 24〕 Barn owls range in colour from the almost beige-and-white nominate subspecies, ''erlangeri'' and ''niveicauda'', to the nearly black-and-brown ''contempta''.〔Bruce (1999) pp. 34–75〕 In the ''Handbook of Birds of the World, Volume 5: Barn-owls to Hummingbirds'', the following subspecies are listed:〔Bruce (1999) pp. 34–75〕 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「barn owl」の詳細全文を読む スポンサード リンク
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