|
__NOTOC__ The common potoo, grey potoo, lesser potoo or poor-me-one (''Nyctibius griseus''), is a nocturnal bird which breeds in tropical Central and South America from Nicaragua to northern Argentina and northern Uruguay. The northern potoo (''N. jamaicensis'') was formerly classified as a subspecies of this species. This potoo is a large cypselomorph bird related to the nightjars and frogmouths, but like other potoos it lacks the bristles around the mouth found in the true nightjars. It is 33–38 cm long and pale greyish to brown, finely patterned with black and buff, camouflaged to look like a log; this is a safety measure to help protect it from predators, but its ''mode of perch'' is also a camouflage. It has large orange eyes. The common potoo can be located at night by the reflection of light from its eyes as it sits on a post, or by its haunting melancholic song, a ''BO-OU, BO-ou, bo-ou, bo-ou, bo-ou, bo-ou, bo-ou, bo-ou'' dropping in both pitch and volume.It has special disruptive coloration so it camouflages into a branch, as shown on the picture.〔Cott, Hugh (1940). ''Adaptive Coloration in Animals.'' Oxford University Press. pp. 352–353.〕 It is a resident breeder in open woodlands and savannah. It avoids cooler montane regions, rarely occurring over 1,900 meters ASL even in the hottest parts of its range. Also, arid regions are usually avoided; for example in the dry Caribbean plain of Colombia the species was first recorded in April 1999. In gallery forest-type environment around the Uruguayan-Brazilian border, it is by no means uncommon. A bit further south, where the amount of wood- versus grassland is somewhat lower, it is decidedly rare, and due west, in the Entre Ríos Province of Argentina with its abundant riparian forest it is likewise not common. The birds at the southern end of their range may migrate short distances northwards in winter.〔Cuervo ''et al.'' (2003), Strewe & Navarro (2004), Azpiroz & Menéndez (2008)〕 This nocturnal insectivore hunts from a perch like a shrike or flycatcher. During the day it perches upright on a tree stump, and is completely invisible, looking like part of the stump because it stays so completely still as it perches. If disturbed by larger animals, such as common marmosets (''Callithrix jacchus''), it may break its camouflage and try to chase them away however.〔de Lyra-Neves ''et al.'' (2007)〕 The single egg is white with lilac spots.〔 It is laid directly in a depression in a tree limb,〔E.g. of ''Cecropia'': Greeney ''et al.'' (2004)〕 usually some meters above ground. It is not clear whether there can be, on occasion, two eggs in a clutch.〔Greeney ''et al.'' (2004)〕 This widespread species is not considered threatened by the IUCN.〔BLI (2008)〕 ==Footnotes== 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「Common potoo」の詳細全文を読む スポンサード リンク
|