The grey-necked rockfowl (Picathartes oreas) is a medium-sized bird in the family Picathartidae with a long neck and tail. Also known as the grey-necked picathartes, this passerine is mainly found in rocky areas of close-canopied rainforest from south-west Nigeria through Cameroon, Equatorial Guinea, and south-west Gabon. It additionally lives on the island of Bioko. Its distribution is patchy, with populations often isolated from each other. The rockfowl typically chooses to live near streams and inselbergs in its forested habitat. It has no recognized subspecies, though some believe that it forms a superspecies with the white-necked rockfowl. The grey-necked rockfowl has grey upperparts, a light grey breast, and lemon-coloured underparts. Its unusually long tail is used for balance, and its thighs are muscular. The head is nearly featherless, with the exposed skin being powder blue on the forehead and upper mandible and carmine on the hindcrown. The bird's cheeks and eyes are covered in a large, circular black patch that, though narrow, connects and divides the carmine and powder blue skin at the peak of the crown. Though the bird is usually silent, some calls are known.
This rockfowl feeds primarily on insects, though some plant matter, such as fruit and flower buds, is eaten. One feeding strategy involves following Dorylus army ant swarms, feeding on insects flushed by the ants. Rockfowl move through the forest mainly through a series of hops and bounds, or short flights in low vegetation. It travels either alone or in small groups. This species rarely flies for long distances. The grey-necked rockfowl is monogamous and pairs nest either alone or in the vicinity of other pairs, sometimes in colonies of two to five nests, though one colony of forty nests has been recorded. These nests are constructed out of mud and are formed into a deep cup that is built on rock surfaces, typically in caves or on cliffs. Two eggs are laid twice a year. Though the birds breed in colonies, infanticide exists in this species, with rockfowl attempting to kill the young of other pairs. Nestlings mature in about a month.
This species is classified as vulnerable as its dwindling and fragmented populations are threatened by habitat destruction. A conservation plan has been drawn up for this species, and research into its current distribution is ongoing. Some of the indigenous peoples of Cameroon either respect this species or, in some cases, fear it. Today, this rockfowl is considered one of Africa's most desirable birds by birders and is a symbol of ecotourism across its range.
Taxonomy 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.
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.
Description This rockfowl measures approximately in length, with its notably long tail contributing about . 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 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 .
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.
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".
Distribution and habitat
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 .
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 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 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 of their nesting site throughout the year. It is capable of living near human activity, and one breeding site in Cameroon was located within of a maize plot. This and other recent observations suggest that the rockfowl has greater tolerance for degraded habitat than previously thought.
Ecology and behavior This rockfowl usually lives either alone or in pairs, although small flocks of three to ten birds are not uncommon. It normally moves through its habitat in a series of runs and long, springing hops on the ground and in low branches. It uses its tail for balance while hopping and running. When in a flock, rockfowl hop almost in unison. In the unusual occurrences when the species does fly, it is fast and is capable of navigating through the trees and rocks well. When it is standing still, the rockfowl has its tail down and its head looking up. Typically, it silently evades any unusual movements in their forest. However, if these birds know that they have been sighted, they can become quite inquisitive and occasionally approach observers. This is not a shy species once it knows that it has been seen, and often studies things of interest, including humans, from an open location. When this species is suspicious, it raises the small crown on its head and the ruff on its neck while uttering a muffled groan. It is most active in the early morning and late evening, and from 10:30 am to 7:00 pm remains perched with little activity either in liana-tangled areas or in caves away from the nests. To scratch its head, the species lifts its foot over its head. It bathes in small pools. While its lifespan in the wild is unknown, it has lived up to 25 years in captivity.
Diet
This species forages in the early morning or late afternoon either alone or in small groups in leaf litter and on dead tree trunks. It is also known to leap upwards to grab prey on overhanging foliage. It looks for its prey either by standing still and scanning the surrounding area or by tossing the leaf litter away with its beak. It also frequently follows columns of Dorylus ants, feeding on the insects flushed by the ants. It also is known to hunt in streams for crabs and fish. It crushes snails with its beak and, if its prey struggles, smashes it against the ground. While an uncommon occurrence, male rockfowl have been observed giving food to a female.