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Justification of Red List category
This species is listed as Vulnerable because its very small, severely fragmented range is undergoing a continuing decline in the area of occupancy and in the extent and quality of habitat, owing to deforestation and forest degradation. However, the species may be discovered at new locations in the future, now that its distinctive calls are known.

Population justification
Fuller et al. (2004a, 2004b) estimated a population of 44,038 (95% CI: 32,827-59,079) individuals in Uganda. However, the species's distribution also includes localities in the Democratic Republic of the Congo, the inclusion of which may double the known population size (R. Fuller in litt. 2007), therefore the population is placed in the range 50,000-99,999 individuals.

Trend justification
The species's range is known to be in decline where its status has been inferred through changes in habitat extent in Uganda (Fuller et al. 2004b), and its population is suspected to be in decline owing to habitat destruction and hunting pressure, although the likely rate of decline has not been estimated.

Ptilopachus nahani is known from a few localities in the eastern Democratic Republic of the Congo (DRC) from Yangambi eastwards, and in central and western Uganda in Budongo, Bugoma (401 km²) and Mabira (210 km²) Forests (Dranzoa et al. 1999; McGowan 1994). Recent surveys estimated the population in Uganda to be 44,038 (95% CI: 32,827-59,079) individuals (Fuller et al. 2004a,b). Its reported presence in Bwamba (= Semliki) and Kibale (560 km²) Forests (Uganda) has never been confirmed and is best discounted (M. Carswell in litt. 1999; Dranzoa et al. 1999; D. Pomeroy in litt. 1999; E. Sande per R. Ssemmanda in litt. 2007). It is known to be uncommon in the still extensive Ituri Forest, DRC, and fairly common in Budongo Forest, Uganda (Plumptre 1996). Surveys in the DRC took place in 2005, and call playback methods were used to successfully locate 12 groups in Irangi Forest over one month (Fuller et al. 2006). This population may not be viable in the long-term due to the small size and isolation of this patch of forest. Surveys in the lowland sector of Virunga National Park were unsuccessful in finding any birds (Fuller et al. 2006). The species's range is in decline throughout its highly fragmented distribution (Fuller et al. 2004b). Tracewski et al. (2016) estimated the maximum Area of Occupancy (calculated as the remaining tree area within the species’s range) to be c.1,349 km², rounded here to 1,300 km².

It is found in lowland primary forest, preferring riverine or swampy areas (Dranzoa et al. 1999; McGowan 1994). In Uganda, it occurs in both unlogged and logged forest (Sande 2001), including mixed forest subject to moderate logging and/or disturbance, or where natural gaps occur (Dranzoa et al. 1999). Records from forest edge and non-forest habitats may refer to dispersing or feeding birds (Fuller et al. 2004a, 2004b). It prefers to forage in areas of dense understorey with a tall, dense canopy and sparse ground vegetation (Sande 2001; Fuller et al. 2004b). Dense canopy cover indicates mature forest containing suitable breeding and roosting sites (Sande et al. 2010), and a dense understorey indicates the presence of preferred feeding habitat; two habitat characteristics that rarely coincide (Fuller et al. 2004b). It searches the leaf-litter for invertebrates, shoots, seeds and bulbs (McGowan 1994) and probably picks invertebrates from low vegetation (Sande 2001). It is highly territorial and breeds throughout the year, though mainly towards the beginning of the rainy season (Sande 2001). Most nests are placed on the ground between the buttresses of large trees (Sande 2001).

The primary threat to this species is thought to be habitat loss through logging and clearance of forest for charcoal burning and agriculture (Fuller et al. 2004b). Fragmentation alone probably does not adversely affect the species, but it does appear to be affected by habitat changes associated with human-induced fragmentation, such as the extensive removal of large trees (Fuller et al. 2004b). Its habitat in Mabira Forest is highly degraded (Dranzoa et al. 1999) and the rapid loss of forest here suggests that the francolin population may be declining (Fuller et al. 2004a, 2004b), making this the most threatened population in Uganda. Plans to raze 7,100 ha of Mabira and sell off the land for sugar production have been suspended (Anon. 2007). While logging in Bugoma Forest may not directly threaten the species, increased disturbance and poaching by pit-sawyers may reduce its population (J. Lindsell in litt. 1999) - both forests are surrounded by agricultural settlements, industrial development and urban areas (Dranzoa et al. 1999). A new wave of invasion by veterans and refugees (arriving from DR Congo) is claiming the remaining chunks of Bugoma and Budongo forests, with an estimated 5,000 ha of Bugoma forest subject to encroachment by about 1,000 families and pit-sawyers for settlement in 2011-2012 (C. Dranzoa in litt. 2012). In Uganda, it is hunted for food, and eggs are collected and eaten or used in traditional practices although this appears to be on a small scale (Dranzoa et al. 1999; Dranzoa 2002; Fuller et al. 2004a, 2004b). Hunting in DRC has not yet been investigated but may be a more serious problem (Fuller et al. 2004a). The exotic tree species Broussonetia papyfera has invaded the eastern part of Mabira Forest and very few francolins were found in this habitat (Fuller et al. 2004a).

Conservation Actions Underway
In the DRC, the population in the Semliki Valley is within the Virunga National Park (McGowan 1994). In Uganda, it occurs in the Bugoma and Mabira Forest Reserves, as well as the Budongo Forest Reserve, which has been sustainably managed for timber since the 1920s (Plumptre 1996). A cycle of monitoring in Budongo Forest has been arranged for 2008 so that data continues to be collected every five years, whilst it is anticipated that the species will be monitored across its global range every 10 years (Fuller et al. 2004b). Settlers encroaching on Bugoma Forest Reserve have been removed by the authorities but may attempt to return (C. Dranzoa in litt. 2012).

Conservation Actions Proposed
Study its ability to disperse between forest patches (R. Fuller in litt. 2007). Use developed playback survey methods, carry out surveys in Uganda before 2015, especially in Mabira Forest, and continue surveys across the species's range at 10 year intervals (Fuller et al. 2004b). Extend surveys for the bird in eastern DRC (lowland sectors of Maiko National Park, lowland sectors of Kahuzi-Biéga National Park, Ituri Forest, and Tayna Forest; Fuller et al. 2004b). Survey forest patches between Bugoma forest and Kibale National Park, Uganda, and within Kibale and Semliki National Parks. Study genetic variation within and among isolated populations. Investigate the impact of the paper mulberry Broussonetia papyrifera invasion in Mabira Forest Reserve and ways of controlling it. Carry out radio-tracking studies on the use of (introduced) Lantana camara thickets by the species (Fuller et al. 2004b). In DRC, extend Virunga National Park to include the eastern Ituri Forest. Initiate projects to alleviate meat shortages and start income generation projects, targeting them particularly at those that still regularly hunt galliformes (Fuller et al. 2004b). Encourage ecotourism projects run by community groups (Fuller et al. 2004b). Encourage villagers to hunt in areas closer to their homes, rather than in forests, and initiate conservation awareness programmes in parallel with the falling popularity of hunting (Fuller et al. 2004b). Enforce existing government forestry policies in Uganda, especially in Mabira Forest (Fuller et al. 2004b).

23-26 cm. Terrestrial gamebird of deep forest. Black underparts with conspicious white spots. Black-and-brown mottled upperparts. White chin. Red base of bill and naked skin around eye. Unspurred, red legs. Sexes alike. Juvenile darker above, spotting on neck does not reach upperside, grey legs. Similar spp. Forest Francolin F. lathami has black throat and yellow legs, lacks red skin around eye. Voice Fluid build-up of double notes, gradually rising in frequency and volume (5-20 seconds long). Hints Found in groups in dense primary forest.

Text account compilers
Ekstrom, J., Taylor, J., Evans, M., Westrip, J., Symes, A., Stattersfield, A., Keane, A., Shutes, S.

Contributors
Dranzoa, C., Ssemmanda, R., Fuller, R., Pomeroy, D., Lindsell, J., Carswell, M.

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Recommended citation
BirdLife International (2024) Species factsheet: Nahan's Partridge Ptilopachus nahani. Downloaded from https://datazone.birdlife.org/species/factsheet/nahans-partridge-ptilopachus-nahani on 22/11/2024.
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 22/11/2024.