|
Fantails are small insectivorous birds of Australasia, Southeast Asia and the Indian subcontinent belonging to the genus ''Rhipidura'' in the family Rhipiduridae. Most of the species are about 15 to 18 cm long, specialist aerial feeders, and named as "fantails", but the Australian willie wagtail, is a little larger, and though still an expert hunter of insects on the wing, concentrates equally on terrestrial prey. The true wagtails are part of the genus ''Motacilla'' in the family Motacillidae and are not close relatives of the fantails. ==Description== The fantails are small bodied (11.5–21 cm long) birds with long tails; in some species the tail is longer than the body and in most the tail is longer than the wing.〔Boles, W.E. (2006). Family Rhipiduridae (Fantails). Pp 200-244 in: del Hoyo, J., Elliott, A. & Christie, D.A. eds (2006) ''Handbook of the Birds of the World''. Vol. 11. Old World Flycatchers to Old World Warblers. Lynx Edicions, Barcelona. ISBN 978-84-96553-06-4〕 When the tail is folded it is rounded at the end, but when spread in display or aerial foraging it has a characteristic fan shape that gives the family its name. Fantails adopt a hunched horizontal posture most of the time, with the wings drooped and held away from the body and the tail half cocked. There are some exceptions to this, particularly the northern fantail of New Guinea and the Cockerell's fantail of the Solomon Islands, which have a more upright posture reminiscent of the monarch flycatchers. The wings of fantails are tapered and have sacrificed speed for agility, making fantails highly efficient at catching insect prey. Overall the fantails are strong fliers, and some species can undertake long migrations, but the thicket fantails (sooty thicket fantail, white-bellied thicket fantail and black thicket fantail) are very weak fliers, and need to alight regularly. The bills of fantails are typical for aerial insect eating birds, being flat and triangular. The gape is surrounded by two rows of rictal bristles which are long, often as long as the bill. The bills of most species are fairly weak, limiting fantails to softer insects, although the more terrestrial willie wagtail has a stronger bill. The plumage of most fantails shows some variation, most species are relatively uniform with some markings.〔 A few species, such as the Rennell fantail, have uniform plumage, while others have striking if sombre patterns. The colours of most species are greys, blacks, whites and browns, although a few species have yellow or even striking blue feathers. In most species there is no sexual dimorphism in plumage; the notable exception being the black fantail of New Guinea where the male has all-over black plumage and the female is almost entirely rufous. In a few species, such as the New Zealand fantail, there exist two colour morphs, the common pied morph and the rarer black morph (which is most common on the South Island).〔Craig, J. (1972) "Investigation of the mechanism maintaining polymorphism in the New Zealand fantail, ''Rhipidura fuliginosa''" (Sparrman), ''Notornis'' 19(1):42-55 ()〕 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「Fantail」の詳細全文を読む スポンサード リンク
|