Tuesday, July 2, 2013

It is estimated that only 2,500 to 10,000 White-necked Rockfowl survive

It is estimated that only 2,500 to 10,000 White-necked Rockfowl survive, with the population dwindling and spread out over a known 32 sites; however, most individuals studying this species believe that the population is far fewer than the 10,000 maximum.[19][20] Many of its colonies are currently approaching the minimum population size necessary to guarantee long-term viability against inbreeding.[19] Sony VGP-BPS22 Battery The primary threat is the commercial destruction of its habitat for timber.[19] Although the White-necked Rockfowl is capable of withstanding some disturbance of the nearby habitat, as demonstrated by one colony surviving after it was completely surrounded by a cocoa plantation, habitat disturbance is far more likely to negatively impact on breeding success.[12][19] Sony VGP-BPL22 Battery Most of the remaining colonies in Guinea, Sierra Leone, and Côte d'Ivoire are on protected land, while Liberia and Ghana's colonies are mostly unprotected.[19] In part to protect this species, Sierra Leone recently upgraded its protection of the Gola forest by turning it into its second national park, Gola National Park, and has announced that the country intends to work with Liberia to form a trans-national park protecting the Gola rainforest.[29] Sony VGP-BPS22A Battery In return for lost logging rights, Sierra Leone has compensated locals with road and school renovations, additional training for police officers, and construction of churches and a mosque.[30] Liberia has also expressed a desire to expand its national park system, which would help protect the species.[19] Sony VAIO PCG-3B1M Battery

 In Guinea, the bird's forests are being logged to provide land for rice farming to help support farmers immigrating from the country's drier north.[13]

Laws exist in Sierra Leone, Liberia, and Ghana to protect this species, but enforcement in minimal.[19][25] Sony VAIO PCG-3D1M Battery International trading of the White-necked Rockfowl is regulated as the bird is currently listed under CITES Appendix I. Additionally, in 2004 BirdLife International drafted an international action plan to provide strategies for protecting this species.[20] This plan focused on surveying the remaining habitat, raising awareness amongst the local populace, and limiting the continued destruction of its habitat.[20] Sony VAIO PCG-3G2M Battery In 2006, BirdLife International received a US$19,900 grant from the Disney Wildlife Conservation Fund to help enact this plan.[31] Surveys conducted with this funding have resulted in the discovery of additional populations in Sierra Leone.[32] Additionally, wardens have been trained to protect Sierra Leone's Western Area Forest Reserve.[32] Sony VAIO PCG-5R1M Battery

This plan, coupled with the bird's appearance and unusual habits, have led it to become a flagship species for habitat conservation across Africa and particularly in its upper Guinean forests.[32]

Until 2003, the species was thought to be extinct in Ghana. Most of the Ghanaian sites from which it is known are active forest reserves, where logging periodically occurs. Sony VAIO PCG-7162M Battery

Outside of the reserves, bush-burning and mining for gold and other metals threaten remaining habitat. Following its rediscovery in Ghana, the Ghana Wildlife Society has begun to survey remaining habitat and implement conservation strategies.[19]

In the 1950s and 1960s, collecting this species for display in zoos was a major threat, and in Liberia in particular this practice destroyed several of the bird's colonies.[13][25Sony VAIO PCG-7181M Battery The rockfowl were captured by the indigenous peoples through the use of traps, while hunters in Guinea, who were already catching rodents and hyraxes at the bird's nesting colonies, sometimes captured rockfowl at night.[13] In Côte d'Ivoire specimens were sometimes caught by bat-catchers.[13] Most birds collected from the wild die within 24 hours.[13] Sony VAIO PCG-41112M Battery Despite over 70 White-necked Rockfowl being displayed in zoos during the 1970s, captive breeding was a rare occurrence and no stable captive populations have been formed.[13] Despite this, zoos did have limited success and at least one zoo was able to hand-rear a White-necked Rockfowl.[33] As of 2002, no White-necked Rockfowl have existed outside of Africa since 1998. Sony VAIO PCG-7153M Battery 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 southwest Nigeria through Cameroon, Equatorial Guinea, and southwest Gabon. It additionally lives on the island of Bioko. Sony VAIO PCG-71312M Battery 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 superspecieswith the White-necked Rockfowl. The Grey-necked Rockfowl has grey upperparts, a light grey breast, and lemon-coloured underparts. Sony VAIO PCG-7144M Battery 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. Sony VAIO PCG-7191L Battery

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. Sony VAIO PCG-3C1M Battery 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. Sony VAIO PCG-3F1M Battery 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. Sony VAIO PCG-3H1M Battery 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. Sony VAIO PCG-3J1M Battery

Today, this rockfowl is considered one of Africa’s most desirable birds by birders and is a symbol of ecotourism across its range.

This species was first described by Anton Reichenow in 1899 from a bird collected at the base of Mount Cameroon near Limbe, Cameroon.[2] He published his description in Ornithologische Monatsberichte and described it as Picathartes oreas.[3] Sony VAIO PCG-8141M Battery The generic name was first used by René-Primevère Lesson in 1828 after he split the Grey-necked Rockfowl's close relative theWhite-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.[4] Sony VAIO PCG-8161M Battery This generic name comes from a combination of the Latin genera pica for "magpie" and cathartes for "vulture".[5][6] The species name is derived from theAncient Greek word oreas, meaning "mountain".[7] Since its initial description, the picathartes have been placed in more than five different families, including those of crows (Corvidae), starlings (Sturnidae), Sony VAIO PCG-3C2M Battery Old World flycatchers (Muscicapidae), babblers (Timaliidae) and Old World warblers (Sylviidae).[8] Today the Grey-necked Rockfowl and the White-necked Rockfowl are believed to comprise a unique family, Picathartidae.[9] Additionally, it has been suggested, though not generally accepted, that the two rockfowl represent the remnants of an ancient bird order.[2] Sony VAIO PCG-5N2M Battery Recent DNA analysis has shown that Picathartidae and its closest relatives, southern Africa's rockjumpers and southeast Asia's Rail-babbler, form a clade.[10] The analysis suggests that the rockfowl split from the common ancestor of their clade 44 million years ago.[10] It is believed that the ancestor of this clade originated in Australia and spread to Africa.[10] Sony PCG-31211T Battery

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.[9]

This species has numerous common names, including the Grey-necked Rockfowl, Grey-necked Picathartes, Sony PCG-31311T Battery Bare-headed Rockfowl, Red-headed Rockfowl, Blue-headed Picathartes, and Grey-necked Bald Crow.[11][12][13] Rockfowl is a reference to the species' habit of building mud nests on rock surfaces and caves.[14] Picathartes refers to the species' scientific name.[5] Bald Crow is a reference to its featherless head and somewhat crow-like appearance, especially in its beak. Sony PCG-51111T Battery 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).[16]This species does not show sexual dimorphism.[15] The adult's head is largely featherless, and the skin on the forehead and forecrown as well as the uppermandible of the beak behind the bird's nostril is a powder blue.[16] Sony PCG-81111T Battery The lower mandible and rest of the upper mandible are black.[16] This beak is unusually large and crow-like at 30 millimetres (1.2 in) in length and is also decurved.[15][17] There are some small, bristle-like feathers located on the crown that can be erected.[15] Behind the crown, the species' bare skin on the hindcrown and nape is carmine in coloration and has a few more bristle-like feathers.[16] Sony PCG-81311T Battery The area between these patches of skin, as well as the lores, cheeks, and ear region, are featherless with black skin.[16] Its eyes are dark brown.[16] The Grey-necked Rockfowl's mantle, back, rump, and uppertail coverts are all grey.[16] The feathers on the rump are long, dense, and silky.[16] Additionally, the tail is grey.[16] Sony VPCF138FC Battery The rockfowl's chin, throat, sides of the neck, and upper breast are all a pale grey.[2] 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.[16] The wing is grey, though the wing's remiges are black, forming a line between the lemon underparts and grey upperparts.[16] Sony VPCF219FC Battery

Its legs and feet are silver-grey and muscular.[15] The adult rockfowl weighs 200 to 250 grams (7.1 to 8.8 oz).[18]

The nestling is born nearly featherless except for tiny primary quills and a fine down along its spine, humerus, forearm, and femur.[16] Its skin is dark pink but displays variable black patches on its upperside.[16] The gape is yellow.[16] Sony VPCS135EC Battery 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.[16] 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.[19] Sony VPCS136EC Battery The Grey-necked Rockfowl is a relatively silent species.[16] It has been known to give a quiet, one to two second long, hissing "wheet" call several times at intervals of about four seconds.[16] To give this call, the rockfowl opens its beak and inflates its throat.[16] When bringing food to their nests, the adults give one or two "peep"s.[16] Sony VPCS138EC Battery

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.[16] It also makes a hissing noise that has been described as a "shisss".

The Grey-necked Rockfowl is found in West Africa from southeast Nigeria to southwest Gabon.[20] Sony VPCS139GC Battery In Nigeria, it is only found in the nation's southeastern corner near the coast and the Cameroon border.[3] The species is widespread in southwestern Cameroon, and this country is considered to be the species' stronghold.[21] It is found throughout Equatorial Guinea and into southwestern Gabon.[20] Additionally, the species resides in the southwestern forests of the island of Bioko in the Gulf of Guinea.[3] Sony VPCYA15EC Battery 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.[2][8] The Grey-necked Rockfowl's total range covers approximately 314,000square kilometres (121,000 sq mi).[20] Sony VPCYA16EC Battery It is found in undisturbed rain forests with closed canopies.[20] The Grey-necked Rockfowl prefers rugged terrain in these forests covered in large boulders, caves, and gorges.[16] Additionally, it often found near inselbergs and a source of water, either a river or a forest pool.[15] The understory of its forests has sparse undergrowth or open spaces but is covered in mosses, Sony VPCYA25EC Battery ferns, lianas, and epiphytes.[16] In southwestern Bioko it is found in low forests that receive nearly 10 metres (33 ft) of rain a year.[16] Bioko's habitat also has dense undergrowth and vertical gorges near a caldera.[16] The rockfowl's habitat is normally found between 450 and 2,100 metres (1,480 and 6,900 ft) above sea level, though it is lower in elevation on Bioko.[16] Sony VPCYA26EC Battery 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.[22] 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.[15] This and other recent observations suggest that the rockfowl has greater tolerance for degraded habitat than previously thought. Sony VPCYB15JC Battery This rockfowl usually lives either alone or in pairs, although small flocks of three to ten birds are not uncommon.[16] It normally moves through its habitat in a series of runs and long, springing hops on the ground and in low branches.[16] It uses its tail for balance while hopping and running.[15] When in a flock, rockfowl hop almost in unison.[22] Sony VPCYA17GH/R Battery In the unusual occurrences when the species does fly, it is fast and is capable of navigating through the trees and rocks well.[22] When it is standing still, the rockfowl has its tail down and its head looking up.[22] Typically, it silently evades any unusual movements in their forest.[23] However, if these birds know that they have been sighted, Sony VPCCW2S8E/W Battery they can become quite inquisitive and occasionally approach observers.[23] 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.[22] When this species is suspicious, it raises the small crown on its head and the ruff on its neck while uttering a muffled groan.[22] Sony VPCCW2Z1E/B Battery 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.[22] To scratch its head, the species lifts its foot over its head.[24] It bathes in small pools.[22] While its lifespan in the wild is unknown, it has lived up to 25 years in captivity. Sony VPCY11S1E Battery This species forages in the early morning or late afternoon either alone or in small groups in leaf litter and on dead tree trunks.[22] It is also known to leap upwards to grab prey on overhanging foliage.[22] It looks for its prey either by standing still and scanning the surrounding area or by tossing the leaf litter away with its beak.[22] Sony VPCY11S1E/S Battery It also frequently follows columns ofDorylus ants, feeding on the insects flushed by the ants.[20] It also is known to hunt in streams for crabs and fish.[14] It crushes snails with its beak and, if its prey struggles, smashes it against the ground.[22] While an uncommon occurrence, male rockfowl have been observed giving food to a female.[26] Sony VPCW1 Battery The Grey-necked Rockfowl feeds on a diverse range of invertebrates and small vertebrates, though plant matter does constitute a major part of its diet.[22][26] It is known to eat beetles, including weevils, rove beetles, and click beetles from the genusPsephus, butterflies, ants from the genera Dorylus and Pachycondyla, grasshoppers, Sony VPCW1E8R/BU Battery cockroaches from the family Blattidae, earwigs,caterpillars, ant-lions, silverfish, and earthworms.[22] Small lizards, frogs, snails, and slugs are also eaten, as are crabs from the genus Potamon, fruits, flower buds, mosses, and leaves.[22][26] Fish have also been identified as a prey item in Nigeria.[14] Sony VPCY11AGJ Battery At at least one nesting site, it relies heavily on the arthropods feeding on the bat guano near the cave for sustenance, while this behaviour has been reported to a lesser extent at other sites.[22][27] It is known to regurgitate what it has eaten in pellet form.[22] Overall, between 52 and 60 percent of the bird's diet is believed to be composed of animals.[26] Sony VPCY11AHJ Battery

Rove beetle larvae and ants were the most frequently eaten prey in a study in Nigeria.

The Grey-necked Rockfowl breeds either alone or in small colonies averaging two to five nests in size, though nearly fifty nests are present at one site.[2] It is monogamous and therefore does not breed with rockfowl other than its mate.[22] Sony VPCY11AVJ Battery It is believed to breed cooperatively in Equatorial Guinea, as four different birds were observed feeding one nest.[28] The rockfowl's courtship displays are unknown.[22] The timing of the egg laying in a colony is not synchronized, leading to various stages of development of nestlings within the colony.[22] Sony VPCY11M1E Battery It has been suggested that this is to promote cooperative breeding.[28] The laying dates also vary by region, typically coinciding with a few weeks before the onset of the wet season;[28] in areas where the wet season is bimodal, two different breeding seasons occur.[2] However, in mountainous regions such as Mount Cameroon, Sony VPCY11S1E Battery it breeds during the dry season to avoid the frequent mists of the wet season.[14] Birds in Nigeria lay their eggs between August and November, birds in Gabon lay between November and April, birds in western Cameroon lay between March and November with peaks of June, July, and October, and birds in southern Cameroon have two breeding seasons, Sony VPCY11V9E Battery

a main one from October to December and a secondary one lasting from April to May.[29] In Equatorial Guinea, nesting occurs in mid-February.[28]

This rockfowl builds its nest onto the sides of rocks, normally in caves, where nests are built both by the entrance and deep within, or on nearly vertical cliff faces, which can be either bare or have some vegetation, though never woody branches, near the nest.[22] Sony VPCY11V9E/S Battery Nests need to be built under an overhang to protect it from water, and the rock surface normally slopes forward slightly.[14] The nests are almost always found near water, which can be in the form of either streams or forest pools.[28] These streams, particularly those located at the base of a nesting cliff, help keep predators away from the nests.[20] Sony VPCY219FJ/S Battery Nests on rock surfaces are normally built 1.2 to 5.2 metres (3.9 to 17 ft) above the ground.[22] In addition to the rock face nests, there is a record of a nest being constructed on the buttress root of a Piptadeniastrum tree above a small stream.[14] Two nests were even built onto a concrete bridge in Gabon's Lopé National Park.[30] Sony VPCY21AFJ Battery The male and female rockfowl work equally on the nest's construction, and it can take two to three months to build one, though in some extreme cases it takes more than a year.[22] The nest itself is a half-cup constructed of dry mud with grass fibres and dead leaves mixed in, often with the plant matter sticking out of the nest's walls.[22] Sony VPCY21AGJ Battery It is either built onto the rock surface or, in some cases, is built more like a retaining wall across the opening of a small rock fissure.[22] Nests are built at least away 1 metre (3.3 ft) from each other, and in some cases up to 5 metres (16 ft).[28] The nest is normally 30 to 40 centimetres (12 to 16 in) thick, though the nest is uneven in its construction and one nest was 140 centimetres (55 in) thick.[22] Sony VPCY21AHJ Battery It is about 290 centimetres (110 in) wide and 400 centimetres (160 in) long and weighs about 3 kilograms (6.6 lb).[22] However, nest sizes do have a large degree of variability.[19] After the mud dries, it becomes a very hard structure.[22] The inside of the nest is lined with rootlets and thin strips of grass.[22] Sony VPCY21AVJ Battery One to three eggs, normally two, are laid, with the second egg being laid between 24 and 48 hours after the first.[20] The eggs are variable in coloration and can be a light yellow-brown with dark brown blotches, creamy white with dark brown or grey blotches, or pale grey with brown mottling.[22] The eggs weigh about 15.2 grams (0.54 oz) and have an average size of 40.5 millimetres (1.59 in) by 27.5 millimetres (1.08 in).[29] Sony VPCY21S1E/L Battery

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