Colobus guereza is arboreal but will travel across the ground between patches of forest. It occupies a wide range of forest types including low, mid-altitude (=transition), and montane moist forest, ground water forest, secondary forest, riverine forest, swamp forest, and gallery forest. Often common in secondary or degraded forest (Fashing and Oates 2013, Groves and Ting 2013). More than any other African colobine, C. guereza does well in secondary forest and on forest edges (Struhsaker 1972, 1975, Oates 1977, 1996, Butynski 1984, Oates et al. 1990, Fashing and Oates 2013, Fashing 2022). For instance, moderate levels of logging in Kibale National Park resulted in an increase in abundance (Skorupa 1986, Johns and Skorupa 1987, Struhsaker 1997, 2010, Chapman et al. 2000). This may be partly due to dietary and behavioural flexibility and adaptability, and to the greater availability of fast-growing, high-protein/lower-fibre colonizing plants that occur in disturbed habitats (Onderdonk and Chapman 2000).

Colobus guereza is largely folivorous in some regions, but feeds both on leaves and fruits in others (Fashing and Oates 2013). The leaf component of diet ranges from 51% (Budongo, western Uganda; Plumptre et al. 2006) to 87% (Kalinzu, southwestern Uganda; Matsuda et al. 2020) leaves. The diet in disturbed and fragmented forests is comprised of more fruit than in undisturbed forests (Tesfaye et al. 2021). 

In the Awi Zone, northern Ethiopia, C. g. guereza is most abundant in dry evergreen Afromontane forest at 1,859-2,557 m asl (Kifle and Bekele 2023). A total of 31 food plant species were recorded in Wof-Washa Natural Forest (Yazezew et al. 2023). The authors provide a list of the most consumed food items in both natural forest and in plantations. Plantation forest can provide effective buffer zones and corridors (Yazezew et al. 2023).

Group size of C. guereza ranges from 2 to 23 individuals (Suzuki 1979, Fashing and Cords 2000), and group home ranges are 1.5-100 ha (Fashing and Oates 2013, Groves and Ting 2013).

Adult male C. guereza emit a loud call (roar) daily, often around dawn. The roar appears to serve at least three roles: maintenance of intergroup spacing, predator alarm, and predator intimidation (Kingdon 1971, Marler 1972, Walek 1978, Oates and Trocco 1983, Poirier-Poulin and Teichroeb 2020). In favourable circumstances, the roar of C. guereza can be heard at >2 km (Butynski and De Jong 2022a).

An overview of the natural history and conservation of C. guereza is provided in Fashing (2022) and Butynski and De Jong (2022a).

Colobus guereza is endemic to equatorial Africa and has a large geographic range, by far the widest distribution of any African colobine (~2,750,000 km²); C. g. occidentalis alone accounts for 2,100,000 km² (Butynski and De Jong 2022a). This species ranges from eastern Nigeria and Cameroon, eastwards across the Oubangui River in the Central African Republic (CAR) to the northern Democratic Republic of Congo (DRC), and then discontinuously eastwards to southern South Sudan, Uganda, the Kenyan and Ethiopian Highlands, and Mount Kilimanjaro, Mount Meru, and Kahé District of Tanzania (Fashing and Oates 2013, Butynski and De Jong 2022a).

Eight subspecies are recognised here:

Colobus guereza occidentalis (Western Guereza) occurs from eastern Nigeria (Ngel Nyaki Forest Reserve on the western escarpment of the Mambilla Plateau) and the Yabassi District of Cameroon, southwards to northeastern Gabon, and eastwards across western and southern CAR through southern South Sudan and western Uganda to the Nile River, including the Otzi Mountains in northwestern Uganda (Oates 2011, Fashing and Oates 2013, De Jong and Butynski 2014, J. Hart pers. comm. 2016). Geographic range about 2,100,000 km², altitudinal range 170-2,500 m asl (Butynski and De Jong 2022a).

Colobus guereza guereza (Omo River Guereza) is endemic to Ethiopia. It occurs in the Ethiopian Highlands west of the Eastern Rift Valley, down into the lowland forests along the Awash River and Blue Nile Gorge (Fashing and Oates 2013, Zinner et al. 2019, Butynski and De Jong 2022a, 2022b). Overtaken by C. g. poliurus in the southern part of the range (presumably in Jimma Zone). Limits of its distribution, particularly in the southern extent of the range, poorly understood. Geographic range about 450,000 km², altitudinal range 400-3,350 m asl (Butynski and De Jong 2022a, 2022b).

Colobus guereza poliurus (Greyish-white-tailed Guereza) occupies lowland forest along the Omo River and its tributaries in the West and South Omo Zones of southwestern Ethiopia. Isolated populations are present in southeastern South Sudan (De Beaux 1943, Napier 1985, Groves 2001, 2007, Butynski and De Jong 2022b). It occurs in Mago National Park and Omo National Park, perhaps as far north as Jimma, Kaffa Region (Carpaneto and Gippoliti 1990). Overtaken by C. g. guereza in the northern part of the range (presumably in Jimma Zone). Limits of its distribution are poorly understood. Geographic range about 70,000 km², altitudinal range 350-830 m asl (Butynski and De Jong 2022b).

Colobus guereza gallarum (Djaffa Mountains Guereza) is endemic to the Ethiopian Highlands east of the Eastern Rift Valley (Fashing and Oates 2013, Zinner et al. 2019, Butynski and De Jong 2022a, 2022b). Geographic range about 24,000 km², altitudinal range 1,300-3,400 m asl (Butynski and De Jong 2022a, 2022b).

Colobus guereza dodingae (Dodinga Hills Guereza) is endemic to the Imatong Mountains in southeastern South Sudan and Agoro Agu Forest Reserve, central northern Uganda. It is reported to occur in the hills in and around Kidepo Valley National Park, northeastern Uganda (De Jong and Butynski 2014, 2022b, De Jong and Butynski 2015). Geographic range about 6,100 km², altitudinal range 660-2,680 m asl (Butynski and De Jong 2022a, De Jong and Butynski 2023).

Colobus guereza matschiei (Mau Forest Guereza) is endemic to southwestern Kenya, northwestern Tanzania, and extreme eastern Uganda. It occurs west of the Eastern Rift Valley (e.g., Mau Forest Complex, Kakamega Forest National Reserve, Cherangani Hills, and Loima Hills in Kenya, and Mount Elgon National Park on the Kenya-Uganda border), and in groundwater woodlands within the Eastern Rift Valley (including Lake Naivasha and Lake Nakuru National Park). It is also found along the Grumeti River in the western Serengeti, northwestern Tanzania (Butynski and de Jong 2012, Fashing and Oates 2013, De Jong and Butynski 2023). Reports of presence in the Ngorongoro Crater Highlands (e.g., Groves 2001) are unfounded (Butynski and De Jong 2012). Geographic range about 75,000 km², altitudinal range 630-3,010 m asl (Butynski and De Jong 2022a, De Jong and Butynski 2023).

Colobus guereza percivali (Mount Uarges Guereza) is endemic to the Matthews Range and Ndoto Range of central Kenya (Mwenja 2007, De Jong and Butynski 2012, Fashing and Oates 2013). Geographic range about 4,200 km², altitudinal range 1,380-2,080 m asl (Butynski and De Jong 2022a, De Jong and Butynski 2023).

Colobus guereza kikuyuensis (Mount Kenya Guereza) is endemic to the Kenya Central Highlands, including Ngong Escarpment, Mount Kenya, Aberdare Range, and small forest fragments in the Highlands, such as Ol Arabel Forest Reserve (Fashing and Oates 2013, De Jong and Butynski 2023). Geographic range about 15,400 km², altitudinal range 1,700-3,100 m asl (Butynski and De Jong 2022a, De Jong and Butynski 2023).

Photographic maps of the above subspecies can be found on www.wildsolutions.nl

Colobus guereza is listed on Appendix II of CITES and on Class B of the African Convention on the Conservation of Nature and Natural Resources. It occurs in many protected areas throughout its range and is common in many protected areas. Further taxonomic work is needed to assess the validity of the subspecies. For the long-term survival of C. guereza it is essential to determine the extent of the geographic distribution of all subspecies, investigate all threats and their impacts, establish and secure connectivity among forest fragments, and exclude livestock from forest fragments to avoid further forest degradation.