|
}} }} Kingfishers are a group of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found outside of the Americas. The group is treated either as a single family, the Alcedinidae, or as a suborder Alcedines containing three families, Alcedinidae (river kingfishers), Halcyonidae (tree kingfishers), and Cerylidae (water kingfishers). Roughly 90 species of kingfishers are described. All have large heads, long, sharp, pointed bills, short legs, and stubby tails. Most species have bright plumage with few differences between the sexes. Most species are tropical in distribution, and a slight majority are found only in forests. They consume a wide range of prey, as well as fish, usually caught by swooping down from a perch. While kingfishers are usually thought to live near rivers and eat fish, most of them live away from water and eat small invertebrates. Like other members of their order, they nest in cavities, usually tunnels dug into the natural or artificial banks in the ground. A quarter of all kingfishers nest in disused termite nests. A few species, principally insular forms, are threatened with extinction. In Britain, the word "kingfisher" normally refers to the common kingfisher. ==Taxonomy, systematics and evolution== The taxonomy of the three families is complex and rather controversial. Although commonly assigned to the order Coraciiformes, from this level down confusion sets in. The kingfishers were traditionally treated as one family, the Alcedinidae, with three subfamilies, but following the 1990s revolution in bird taxonomy, the three former subfamilies are now often elevated to familial level. That move was supported by chromosome and DNA–DNA hybridisation studies, but challenged on the grounds that all three groups are monophyletic with respect to the other Coraciiformes. This leads to them being grouped as the suborder Alcedines. The tree kingfishers have been previously given the familial name Dacelonidae, but Halcyonidae has priority. The centre of kingfisher diversity is the Australasian region, but the group is not thought to have originated there. Instead, they evolved in the Northern Hemisphere and invaded the Australasian region a number of times.〔 Fossil kingfishers have been described from Lower Eocene rocks in Wyoming and Middle Eocene rocks in Germany, around 30–40 million years ago. More recent fossil kingfishers have been described in the Miocene rocks of Australia (5–25 million years old). Several fossil birds have been erroneously ascribed to the kingfishers, including ''Halcyornis'', from the Lower Eocene rocks in Kent, which has also been considered a gull, but is now thought to have been a member of an extinct family.〔 Amongst the three families, the Alcedinidae are basal to the other two families. The few species found in the Americas, all from the family Cerylidae, suggest that the sparse representation in the Western Hemisphere resulted from just two original colonising species. The family is a comparatively recent split from the Halcyonidae, diversifying in the Old World as recently as the Miocene or Pliocene. 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「kingfisher」の詳細全文を読む スポンサード リンク
|