Picatartes Cuelligrís

Identificación

This rockfowl measures approximately 33 to 38 centimetres (13 to 15 in) in length, with its notably long tail contributing about 14 centimetres (5.5 in). This species does not show sexual dimorphism. The adult's head is largely featherless, and the skin on the forehead and forecrown as well as the upper mandible of the beak behind the bird's nostril is a powder blue. The lower mandible and rest of the upper mandible are black. This beak is unusually large and crow-like at 30 millimetres (1.2 in) in length and is also decurved. There are some small, bristle-like feathers located on the crown that can be erected. Behind the crown, the species' bare skin on the hindcrown and nape is carmine in coloration and has a few more bristle-like feathers. The area between these patches of skin, as well as the lores, cheeks, and ear region, are featherless with black skin. Its eyes are dark brown. The grey-necked rockfowl's mantle, back, rump, and uppertail coverts are all grey. The feathers on the rump are long, dense, and silky. Additionally, the tail is grey. The rockfowl's chin, throat, sides of the neck, and upper breast are all a pale grey. This bird is buffy lemon in colour on its lower breast, belly, flanks, thighs, and undertail coverts, though the flanks can sometimes appear to be greyish. The wing is grey, though the wing's remiges are black, forming a line between the lemon underparts and grey upperparts. Its legs and feet are silver-grey and muscular. The adult rockfowl weighs 200 to 250 grams (7.1 to 8.8 oz).<p>The nestling is born nearly featherless except for tiny primary quills and a fine down along its spine, humerus, forearm, and femur. Its skin is dark pink but displays variable black patches on its upperside. The gape is yellow. As the nestling develops, its plumage begins to resemble that of the adult, though it has white flecks on its wing coverts and the featherless skin on the head is black or dark brown, not powder blue, on the forecrown and dark reddish brown, not carmine, on the hindcrown. After fledging, the immature closely resembles the adult except for the bare patch on the back of the head being golden yellow instead of carmine and the tail being only a third as long as that of an adult.<p>The grey-necked rockfowl is a relatively silent species. It has been known to give a quiet, one to two second long, hissing "wheet" call several times at intervals of about four seconds. To give this call, the rockfowl opens its beak and inflates its throat. When bringing food to their nests, the adults give one or two "peep"s. After reaching the nest, the adult repeatedly makes a low "ga-a-a" sound that has been described as being between a snore and a sigh. It also makes a hissing noise that has been described as a "shisss".

Taxonomía

This species was first described by Anton Reichenow in 1899 from a bird collected at the base of Mount Cameroon near Limbe, Cameroon. He published his description in Ornithologische Monatsberichte and described it as Picathartes oreas. The generic name was first used by René-Primevère Lesson in 1828 after he split the grey-necked rockfowl's close relative the white-necked rockfowl from the crow genus Corvus and placed it in its own genus, Picathartes, as the white-necked rockfowl did not share characteristics common to members of Corvus such as a feathered head. This generic name comes from a combination of the Latin genera pica for "magpie" and cathartes for "vulture". The species name is derived from the Ancient Greek word oreas, meaning "mountain". Since its initial description, the picathartes have been placed in more than five different families, including those of crows (Corvidae), starlings (Sturnidae), Old World flycatchers (Muscicapidae), babblers (Timaliidae) and Old World warblers (Sylviidae). Today the grey-necked rockfowl and the white-necked rockfowl are believed to comprise a unique family, Picathartidae. Additionally, it has been suggested, though not generally accepted, that the two rockfowl represent the remnants of an ancient bird order. Recent DNA analysis has shown that Picathartidae and its closest relatives, southern Africa's rockjumpers and south-east Asia's rail-babbler, form a clade. The analysis suggests that the rockfowl split from the common ancestor of their clade 44 million years ago. It is believed that the ancestor of this clade originated in Australia and spread to Africa. Though the grey-necked rockfowl has no subspecies, it may form a superspecies with the white-necked rockfowl, with plumage and facial pattern being the main differences between the two species.<p>This species has numerous common names, including the grey-necked rockfowl, grey-necked picathartes, bare-headed rockfowl, red-headed rockfowl, blue-headed picathartes, and grey-necked bald crow. Rockfowl is a reference to the species' habit of building mud nests on rock surfaces and caves. Picathartes refers to the species' scientific name. Bald crow is a reference to its featherless head and somewhat crow-like appearance, especially in its beak.

Nombre científico

Picathartes oreas

Autoridad

Reichenow, 1899

Orden

Passeriformes

Familia

Picathartidae

Género

Picathartes

Distribución y hábitat

The grey-necked rockfowl is found in West Africa from southeast Nigeria to southwest Gabon. In Nigeria, it is only found in the nation's southeastern corner near the coast and the Cameroon border. The species is widespread in southwestern Cameroon, and this country is considered to be the species' stronghold. It is found throughout Equatorial Guinea and into southwestern Gabon. Additionally, the species resides in the southwestern forests of the island of Bioko in the Gulf of Guinea. There is only one record of this species from the Republic of the Congo, though it is suspected that the rockfowl may have an undiscovered population in this country. The grey-necked rockfowl's total range covers approximately 314,000 square kilometres (121,000 sq mi).<p>The grey-necked rockfowl prefers rugged terrain in these forests covered in large boulders, caves, and gorges. Additionally, it often found near inselbergs and a source of water, either a river or a forest pool. The understory of its forests has sparse undergrowth or open spaces but is covered in mosses, ferns, lianas, and epiphytes. In southwestern Bioko it is found in low forests that receive nearly 10 metres (33 ft) of rain a year. Bioko's habitat also has dense undergrowth and vertical gorges near a caldera. The rockfowl's habitat is normally found between 450 and 2,100 metres (1,480 and 6,890 ft) above sea level, though it is lower in elevation on Bioko. This species is non-migratory, and at one site in Cameroon the birds remained within 300 metres (980 ft) of their nesting site throughout the year. It is capable of living near human activity, and one breeding site in Cameroon was located within 30 metres (98 ft) of a maize plot. This and other recent observations suggest that the rockfowl has greater tolerance for degraded habitat than previously thought.

Migración

Especie residente

Comportamiento

Patrón migratorio: Especie residente.

Conservación

Tendencia poblacional: en declive.

Tendencia poblacional

en declive