Grey-necked Rockfowl (Picathartes oreas) | Text

Grey-necked Rockfowl Picathartes oreas

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Justification

Justification of Red List category

This species qualifies as Near Threatened, because although it has a large range, it is suspected to have a small population size which is experiencing a continuing decline, owing primarily to the clearance and degradation of its habitat.

Population justification
The total population is almost certainly less than 10,000 mature individuals (C. Bowden in litt. 1999; R. Fotso in litt. 1999; H. Thompson in litt. 2000). The suspected population size is therefore placed in the band 2,500-9,999 mature individuals.

Trend justification
This species is inferred to be declining overall. It has very specific habitat requirements (Atuo et al. 2016), and is experiencing continued habitat loss and degradation (Global Forest Watch 2020; Atuo et al. 2016) in addition to hunting pressure and disturbance (Atuo et al. 2016; Odiwumi & Abatcha 2018). The likely rate of decline has not been directly quantified, but is suspected to fall in the band of 1-10%.

Distribution and population

Picathartes oreas occurs in Nigeria (Cross River State, the most recent survey suggests at least 164 breeding individuals [Atuo et al. 2016]), western and southern Cameroon (localised, fewer than 4,000 and probably declining), Gabon (fewer than 1,000 and stable), and south-west Bioko and continental Equatorial Guinea (fewer than 500 and stable) (Bian et al. 2006). A sighting of this species at Mayombe Forest in Congo in December 1994 was recently published (Mamonekene and Bokandza-Paco 2006), and the species is expected to be resident in the north-western tip of the country (potentially a few hundred) (Bian et al. 2006). It has been found on the Boumba river, south-eastern Cameroon, but it is not as yet known from the intervening area, and in 2009 six nests were found c.140 km to the east near Bayanga in the Dzanga Sangha Reserve, Central African Republic (Cassidy et al. 2010). In March 2000, it was discovered on Mt Doudou in south-west Gabon, which represented a considerable southern range extension (P. Christy in litt. 2000), until the publication of the record from Congo in 1994, which now stands as the southernmost record (Mamonekene and Bokandza-Paco 2006). A report from Old Oyo National Park, Nigeria (Adeyemo and Ayodele 2005), which was thought to represent a significant range extension, appears to have been erroneous (Ezealor et al. 2007). It may be more numerous than once thought (Dowsett-Lemaire and Dowsett 1999), however the majority of colonies comprise no more than 10-15 individuals (R. Fotso in litt. 1999)and the total population is almost certainly less than 10,000 mature individuals (C. Bowden in litt. 1999; R. Fotso in litt. 1999; H. Thompson in litt. 2000). Most of the species's breeding colonies are isolated and close to the minimum for long-term viability (Bian et al. 2006). Surveys in the north-west part of Mbam Minkom forest, southern Cameroon, found apparent declines from 40 breeding individuals in 2003, to 20 in 2007 (Awa 2009). Its distribution is highly fragmented owing to its specialised habitat requirements and the population is believed to be declining as a result of habitat loss (Bian et al. 2006).

Ecology

It inhabits closed-canopy, primary rainforest, but may have a greater tolerance for degraded habitat than previously believed (Thompson and Fotso 2000; R. Fotso in litt. 2007). It feeds mainly on invertebrates (Brosset and Erard 1986), is a strong follower of ant columns, and also takes small vertebrates, primarily frogs and lizards (Thompson and Fotso 2000; Bian et al. 2006; French 2006). Additionally, it commonly feeds on a variety of invertebrates such as grasshoppers, beetles, weevils, earthworms, slugs and snails (Bian et al. 2006). It is recorded at 45-2,100 m in Cameroon (Butynski et al. 1996) but at 250-900 m on Bioko. It nests in caves and on rock-faces and cliffs (although there is a recent report of a nest in the buttress of a large Piptadeniastrum tree [Waltert and Mühlenberg 2000; Bian et al. 2006]) and appears to have very specific breeding habitat requirements, including overhanging rock to protect the nest from rain, and sheer rock and often a seasonal river below to protect it from predators (Tye 1987; Dowsett-Lemaire 2007). It has also been recorded nesting under concrete bridges in Lopé National Park, Gabon (Christy and Maisels 2007). It breeds colonially where nest-sites are limited (Tye 1987), with home ranges of less than 0.5km² (Awa II et al. 2009). The nest is a half-cup of dried mud impregnated with dry grass fibres and dead leaves, in which it lays one to three, but usually two, eggs (Bian et al. 2006). The incubation period is 21-24 days and the fledging period is about 24 days (Bian et al. 2006). In the Dja Reserve, southern Cameroon, nesting occurs between August and October, with activity peaking in September (French 2006), however nesting occurs more widely from March to November in the country, with the peak in August-November (Bian et al. 2006).

Threats

It remains threatened by forest clearance and increasing human disturbance throughout much of its range, and at many sites in Cameroon survives only in poor quality habitat (Thompson and Fotso 1995; Atuo et al. 2016). Forest clearance takes place for agriculture, largely crop fields and cocoa plantations (T. Awa in litt. 2007; R. Fotso in litt. 2007). In many non-protected areas where the species occurs, in Cameroon for example, disturbance is caused by activities such as logging and slash-and-burn agriculture (Bian et al. 2006; Awa II et al. 2009b). In protected areas, encroachment by farmers, hunters and loggers means that these populations are also under threat; and hunters' camps can also disturb the species and lead to abandoned breeding in addition to the removal of eggs and young (Atuo et al. 2014).
In Gabon and Bioko, there is only minimal habitat loss and the species is unlikely to be affected by human activity in the near future, as in these parts of its range it inhabits extremely rugged and inaccessible areas. Adults may be hunted to a limited extent for trade and, on Mt Kupe and the Ebo forest at least, it is often caught in spring-traps set for mammals (Bian et al. 2006; R. Fotso in litt. 2007; R. Whytock in litt. 2012).
The lack of suitable breeding sites, particularly of suitable rocks, may also partly account for its scarcity. However, work in the Ebo forest, Cameroon has shown that nest site availability may not always be a limiting factor for P. oreas populations (Whytock unpubl. data. 2012). Abandoned nests can remain unused for many years on suitable rock faces and population estimates may be unreliable where densities are are derived from nest counts (R. Whytock in litt. 2012). In addition, cannibalism and predation probably contribute to low breeding success (Brosset and Erard 1986; Bian et al. 2006). For example, low nests in Korup are known to be destroyed by chimpanzees Pan troglodytes and drills Papio leucophaeus (Bian et al. 2006). Disturbance resulting from human visits to breeding sites, especially by birdwatchers within the growing ecotourism sector, is becoming a major concern and it can lead to disproportionate effects on breeding success if safe viewing regimes are not put in place (T. Awa in litt. 2007, Awa et al. 2009b).

Conservation actions

Conservation Actions Underway
CITES Appendix I. It occurs in protected areas throughout its range. It is fully protected by national law in Cameroon, but although it cannot be killed, it may be captured and held in captivity under special licence (Bian et al. 2006). Enforcement of this law, however, is minimal (Thompson 2004; R. Fotso and E. Owusu per Thompson 2004). The Cameroon Biodiversity Conservation Society has been preparing a National Important Bird Areas Conservation Strategy, which should include a monitoring plan for globally threatened bird species. An international action plan for this species ran between 2006-2011, but Following an international stakeholder workshop, an international action plan for the species was published in 2006, with a five-year plan to stabilise or increase current populations at key sites (Bian et al. 2006).

Conservation Actions Proposed
Survey one or more known areas to establish baseline population density (H. Thompson in litt. 2000). Obtain distribution and trend data for the species's populations throughout its range (Bian et al. 2006). The low density and often rugged habitat preferred by P. oreas makes traditional sampling methods (such as using line transects to estimate nest site density) ineffective and novel methods need to be developed, such as using camera trap arrays (R. Whytock in litt. 2012). Carry out annual monitoring of previously surveyed sites following the acquisition of baseline data and provide training for potential surveyors (Bian et al. 2006). Study genetics using samples from different subpopulations to assess effective population size and degree of inbreeding. Obtain distribution and trend data for the species's populations throughout its range (Bian et al. 2006). Assess the impact of human activities on the species and reduce the threat of stress caused by human presence and activities (Bian et al. 2006).
Provide better protection and management at key sites (Bian et al. 2006). Reinforce local capacity for the study of the species (Bian et al. 2006). Increase the awareness of tourists, researchers and investors about their impacts on the species, develop an environmental education programme centred on the species and raise awareness amongst stakeholders of its importance (Bian et al. 2006). Train local guides to minimise disturbance to the species (Bian et al. 2006). Restrict access to sites through the use of legislation (Bian et al. 2006), and establish safe viewing regimes at suitable sites to promote ecotourism as an alternative income-generating activity (Awa et al. 2009b).

Identification

Large bird with carmine, black and lilac head. Dark bluish-grey upperparts with silky grey throat and breast and yellow belly. Similar spp. White-necked Rockfowl P. gymnocephalus very similar but ranges do not overlap. Voice Breathy shisss and other clucks and clicks. Mostly silent when foraging. Hints Extremely elusive. Characterised by hopping along the forest floor or short flights between trees, but not known for sustained flights.

Acknowledgements

Text account compilers
Clark, J.

Contributors
Alexander-Marrack, P.D., Awa, T., Benstead, P., Bowden, C., Christy, P., Dowsett-Lemaire, F., Ekstrom, J., Fotso, R., Hall, P., Shutes, S., Symes, A., Taylor, J., Thompson, H.S., Westrip, J.R.S. & Whytock, R.

Recommended citation
BirdLife International (2024) Species factsheet: Grey-necked Rockfowl Picathartes oreas. Downloaded from https://datazone.birdlife.org/species/factsheet/grey-necked-rockfowl-picathartes-oreas on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 22/12/2024.