|
The Accipitridae, one of the four families within the order Accipitriformes (the other order of diurnal birds of prey being Falconiformes), are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a few feeding on fruit. The Accipitridae have a cosmopolitan distribution, being found on all the world's continents (except Antarctica) and a number of oceanic island groups. Some species are migratory. Many well-known birds, such as hawks, eagles, kites, harriers and Old World vultures are included in this group. The osprey is usually placed in a separate family (Pandionidae), as is the secretary bird (Sagittariidae), and the New World vultures are also usually now regarded as a separate family or order. Karyotype data indicate the accipitrids analysed are indeed a distinct monophyletic group, but whether this group should be considered a family or one or several order(s) on their own is a question still to be resolved. == Systematics == The accipitrids have been variously divided into some five to 10 subfamilies. Most share a very similar morphology, but many of these groups contain taxa which are more aberrant. These are placed in their respective position more for lack of better evidence than anything else. It is thus not very surprising that the phylogenetic layout of the accipitrids has always been a matter of dispute. The accipitrids are recognizable by a peculiar rearrangement of their chromosomes.〔 "The karyotypes of most birds consist of a small number of macrochromosomes and numerous microchromosomes. Intriguingly, most accipitrids which include hawks, eagles, kites, and Old World vultures (Falconiformes) show a sharp contrast to this basic avian karyotype. They exhibit strikingly few microchromosomes and appear to have been drastically restructured during evolution."〕 Apart from this, morphology and mtDNA cytochrome ''b'' sequence data give a confusing picture of these birds' interrelationships. What can be said is that the hawks, kites, eagles and Old World vultures as presently assigned in all likelihood do not form monophyletic groups: According to the molecular data, the Buteoninae are most likely poly- or paraphyletic, with the true eagles, the sea eagles, and the buteonine hawks apparently representing distinct lineages. These appear to form a group with the Milvinae, Accipitrinae and Circinae but the exact relationships between the lineages are not at all robustly resolvable with the present data. The Perninae and possibly the Elaninae are older lineages, as are the Old World vultures. The latter are fairly likely also poly- or paraphyletic, with some aberrant species like the bearded and Egyptian vultures standing apart from the naked-necked "true" vultures. 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「Accipitridae」の詳細全文を読む スポンサード リンク
|