This account follows the taxonomic arrangement of Groves (2001), Grubb et al. (2003) and Bocian and Anderson (2013) in recognition of subspecies, with the exception of Colobus angolensis sharpei which is here reinstated as a subspecies based on new molecular evidence (McDonald and Hamilton 2010).

Colobus angolensis is listed as Vulnerable. Despite a very large geographic range, the species is threatened in most parts of its range by habitat loss, degradation and fragmentation caused mainly by collection of timber and fuelwood, conversion of forest to farmland, the expansion of human settlements and encroachment due to a fast growing human population (Bocian and Anderson 2013, McDonald et al. in prep).

Hunting is also a major threat to C. angolensis, particularly in Central Africa. It is targeted for bushmeat because of its large size. Despite the existence of largely intact, suitable and protected habitat in the Domaine de Chasse de Swa-Kibula, southwestern DRC, C. a. angolensis became locally extinct before 1990 due to unsustainable hunting (Dino 2014). Although hunting may be a particularly high threat in the Congo Basin, a number of other populations have already been extirpated from suitable habitats elsewhere, suggesting unsustainable levels of hunting [i.e. Arabuko Sokoke Forest, Kenya (Anderson 2004), North Pare Mountains (Doggart et al. 2008), and Pande Game Reserve, Tanzania (Burgess and Clarke 2000, Doggart 2003)]. In the unprotected Udzungwa Scarp Nature Reserve in the Udzungwa Mountains, Tanzania, Rovero et al. (2012, 2015) documented declines to near local extinction of C. a. sharpei due to hunting in a span of less than 10 years.

This taxon is suspected to have undergone a population decline exceeding 30% during the past 33 years (three generations), and is listed as Vulnerable using criterion A2cd. The threats that caused population reductions in the past are not reversible and have not been eliminated, nor will they be in the foreseeable future.

Colobus angolensis ranges from northeast Angola north to the Congo-Ubangui river system, eastwards (with a disjunct range) to the montane and coastal forests of Tanzania and southeastern Kenya (Anderson et al. 2007, Bocian and Anderson 2013). It occurs from sea level to 2,415 m asl (Nyungwe, Rwanda) in East Africa (Anderson et al. 2007, Fashing et al. 2007).

Eight subspecies are recognised, of which one is undescribed:

• Colobus angolensis angolensis (Sclater’s Angola Colobus) occurs in northeastern Angola, north to the great bend of the Congo River and southwards to perhaps extreme northwestern Zambia (Bocian and Anderson 2013). C. a. angolensis became locally extinct before 1990 in the Domaine de Chasse de Swa-Kibula in southwestern DRC (Dino 2014).

• Colobus angolensis cottoni (Powell-Cotton’s Angola Colobus) is endemic to DRC. It ranges from northeast of the Congo River, east to Lake Albert and north to the Uélé-Ubangui river system (it forms a hybrid zone with C. a. ruwenzorii in the southeast).

• Colobus angolensis ruwenzorii (Rwenzori Angola Colobus) occurs along both sides of the Western (Albertine) Rift, from the Semiliki Valley and the Rwenzori Mountains of extreme eastern DRC and extreme western Uganda, to Rwanda, Burundi and northwestern Tanzania.

• Colobus angolensis cordieri (Cordier’s Angola Colobus) is endemic to DRC between the Lowa River and Luama River from the Lualaba River in the western to near Lake Kivu in the east, where it forms a hybrid zone with C. a. ruwenzorii.

• Colobus angolensis prigoginei (Prigogine’s Angola Colobus) is endemic to Mount Kabobo, eastern DRC.

• Colobus angolensis palliatus (Peters’s Angola Colobus) is found in Kenya and Tanzania. It inhabits extreme southeastern Kenya in the north (Kwale County), the Eastern Arc Mountain blocks of East Usambara, Western Usambara, South Pare, Malundwe, Uluguru and Nguru. It is rare in Nguu. This subspecies is also found in the coastal forests of Tanzania north of the Rufiji River and riverine forest along the Rufiji River (Rogers 1981, Anderson et al. 2007).

• Colobus angolensis sharpei (Sharpe’s Angola Colobus) inhabits areas around Lake Rukwa in southwestern Tanzania to north Malawi and northeastern Zambia. This subspecies might occur in northern Mozambique (Groves and Ting 2013).

• Colobus angolensis ssp. nov. is presumably endemic to the Mahale Mountains, central western Tanzania (Nishida et al. 1981, Groves 2001, Grubb et al. 2003).

Colobus angolensis has a wide geographical range and can be locally abundant. Populations in the eastern part of the range are much more fragmented than populations across the Congo Basin. Densities vary widely (Bocian and Anderson 2013). In a comprehensive survey of the Kenyan range of the species, a total of 55 populations were located, with the Kenyan Colobus angolensis palliatus population estimated at 3,100–5,000 individuals (560–900 groups). In Shimba Hills National Park, southeastern Kenya, there are ca 15 individuals/km². At ca 2,400 individuals (Anderson et al. 2007), this is the largest population in Kenya. It exhibits at high density in Diani, a tourist suburban area with remnant forest and forest patches, where harassment is low. At least 10,000 C. a. sharpie are present in the Udzungwa Mountains, southern Tanzania (Rovero et al. 2009). Densities here are 0.8–5.0 groups km² (2.9–12.0 individuals km²) depending on threats and protection levels (Araldi et al. 2014). The Okapi Wildlife Reserve (central Ituri Forest, DRC) has a density of 16.7 individuals/km² (Bocian 1997).

Colobus angolensis is a medium-sized, arboreal, folivorous primate. It lives in evergreen and semi-deciduous forest, including gallery forests, swamp forest, coastal forest, montane forest, and seasonally flooded forests. The species is rare in mangroves and bush-farm land (Bocian and Anderson 2007). They are generally found in small family groups (2–5 adults), but temporary aggregations of up to 300 animals have been reported in some subspecies. They feed primarily on leaves and seeds but also on fruit pulp, flowers and lichens (Bocian and Anderson 2013).

Colobus angolensis is threatened in most parts of its range by habitat loss, degradation and fragmentation caused mainly by collection of timber and fuelwood, conversion of forest to farmland, the expansion of human settlements and encroachment due to a fast growing human population (Bocian and Anderson 2013, McDonald et al. in prep.). Tourism development is a threat in Kenya and Tanzania.

Colobus angolensis is hunted for meat. Despite largely intact, suitable and protected habitat in the Domaine de Chasse de Swa-Kibula, southwestern DRC, C. a. angolensis became locally extinct before 1990 due to unsustainable hunting (Dino 2014). Although hunting may be a particularly high threat in the Congo Basin, a number of populations have already been extirpated from suitable habitats elsewhere, suggesting that unsustainable levels of hunting occurred [i.e. Arabuko Sokoke Forest, Kenya (Anderson 2004), North Pare Mountains (Doggart et al. 2008), and Pande Game Reserve, Tanzania (Burgess and Clarke 2000, Doggart 2003)]. In the unprotected Udzungwa Scarp Nature Reserve in the Udzungwa Mountains, Tanzania, Rovero et al. (2012, 2015) documented declines to near local extinction of C. a. sharpei due to hunting in a span of less than 10 years.

Illegal hunting for pelts has also been reported in Kenya and Tanzania (Anderson et al. 2007, Rovero et al. 2012).

The major threats for C. a. palliatus in residential areas on the southern Kenya coast are vehicle casualties and electrocution on power lines and transformers which, together, make up 60% of the animal welfare cases recorded by the NGO Colobus Conservation (Colobus Conservation unpubl. data 2017).

Colobus angolensis is hunted for meat, often at unsustainable levels. Populations have been extirpated from the Domaine de Chasse de Swa-Kibula in DRC (Dino 2014), Arabuko Sokoke Forest in Kenya (Anderson 2004), North Pare Mountains and Pande Game Reserve in Tanzania (Burgess and Clarke 2000, Doggart 2003, Doggart et al. 2008), and the Udzungwa Scarp Nature Reserve in the Udzungwa Mountains, Tanzania (Rovero et al. 2012, 2015).

Hunting for pelts has been reported in Kenya and Tanzania (Anderson et al. 2007, Rovero et al. 2012).

 

Colobus angolensis is listed on Appendix II of CITES and on Class B of the African Convention on the Conservation of Nature and Natural Resources. Present in a number of protected areas across its range, including Lomami National Park, Salonga National Park, Virunga National Park and Okapi Wildlife Reserve (DRC), Rwenzori Mountains National Park (Uganda), Nyungwe National Park (Rwanda), Shimba Hills National Reserve (Kenya), and Udzungwa Mountains National Park and Mahale Mountains National Park (Tanzania).

In the Eastern Arc Mountains of Tanzania the species is safe only where there is effective protection, such as in the Udzungwa Mountains National Park.

Colobus Conservation based in Diani, Kenya (the only conservation organisation dedicated to a subspecies of Colobus), promotes the conservation, preservation and protection of C. a. palliatus (and sympatric primate species) and its associated coastal forest habitats.

Colobus angolensis prigoginei is listed as Endangered due to its small range (Mount Kabobo, eastern DRC) and low densities (Plumptre et al. 2008). All other subspecies are listed as Vulnerable.