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East Africa > Uganda > Budongo-Bugoma corridor

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Summary

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Eastern chimpanzees (Pan troglodytes schweinfurthii) are present in Budongo-Bugoma corridor.
It has been estimated that 256 (246-321) individuals occur in the site.
The chimpanzee population trend is decreasing.
The total area of the site is >1000 km².
Chimpanzees are mainly threatened by habitat loss as a result of agricultural expansion. Other threats include human-chimpanzee conflict, construction of roads, advancing urbanisation and infrastructure development, and diseases.
Conservation activities have focused on improving livelihoods of local people and conserving and enriching remaining natural forest.
The site links the chimpanzee populations of Bugoma Central Forest Reserve and Budongo Central Forest Reserve

Landscape in the Budongo-Bugoma region © Jack Lester

Site characteristics

Located in the Western Region of Uganda, the 'Budongo-Bugoma corridor' refers to a landscape that links chimpanzee populations in two large protected areas, Budongo and Bugoma Central Forest Reserves, which are separated by 50 km. The intervening 'corridor' is dominated by household and commercial agriculture and agroforestry plantations, villages and urbanizing areas. Most natural forest in the corridor has been converted to farmland and other land uses since the 1990s (McLennan 2008; Twongyirwe et al. 2015). However, small fragments of degraded riparian forest remain along watercourses and around Papyrus swamps. These remnant forest patches offer some cover for the region's chimpanzees, which range within a landscape dominated by farmland, villages, plantations and the outskirts of urban areas (McLennan 2008; McCarthy et al. 2017; McLennan et al. 2021). The Budongo–Bugoma corridor was recognized as an important ‘Chimpanzee Conservation Unit’ in the 2010–2020 IUCN conservation action plan for eastern chimpanzees (Plumptre et al. 2010).

Table 1. Basic site information for Budongo-Bugoma corridor

Species	'Pan troglodytes schweinfurthii
Area	>1000 km²
Coordinates	Lat: 1.573031 , Lon: 31.269084
Type of site	Non-protected area
Habitat types	Grassland, Subtropical/tropical swamp forest, Agricultural land, Urban areas, Subtropical/tropical heavily degraded former forest
Type of governance

IUCN habitat categories Site designations

Budongo-Bugoma Corridor Region Forest Cover (modified from McCarthy et al., 2015)

Ape status

Despite its name, the Budongo-Bugoma corridor is not a migratory corridor for chimpanzees travelling between the Budongo and Bugoma Forests. A regional survey by McLennan (2008) showed that chimpanzees were resident and widely distributed throughout the corridor landscape. Based on an extrapolation of chimpanzee density for one resident community within the corridor, Bulindi Area, McLennan estimated a total regional population of 260 individuals. A genetic mark-recapture study conducted in 2012-2013 confirmed this approximate population size distributed broadly throughout a network of mostly unprotected forest fragments between the Budongo and Bugoma Forests (McCarthy et al. 2015). The population comprises ten or more resident chimpanzee communities (McCarthy et al. 2015, 2018; BCCP, unpublished data 2024). More recent work in this region has indicated declines in some of the community-specific abundance estimates reported by McCarthy and colleagues (BCCP, unpublished data). However, several additional chimpanzee communities have been confirmed present in the southern portion of the corridor that were not included in the earlier surveys (BCCP, unpublished data 2024).

Table 2. Ape population estimates reported for Budongo-Bugoma corridor

Species	Year	Occurrence	Encounter or vistation rate (nests/km; ind/day)	Density estimate [ind./ km²] (95% CI)	Abundance estimate (95% CI)	Survey area	Sampling method	Analytical framework	Source	Comments	A.P.E.S. database ID
Pan troglodytes schweinfurthii	2013			0.4 (0.34-0.47)	256 (246-321)	633 sq. km Budongo-Bugoma corridor	Genetic (dung/hair)		McCarthy et al. 2015

Threats

Chimpanzees in the Budongo-Bugoma Corridor region are threatened principally by habitat loss, as remaining areas of riparian forest are logged for timber and converted for small-scale and commercial agriculture. In addition to commercially produced crops such as tobacco, rice and sugarcane (McLennan & Hill 2015), exotic timber is also widely grown, including species such as eucalyptus and Caribbean pine. Growing infrastructure, including the construction of paved roads for oil extraction, has increased the risks for chimpanzees, and chimpanzees have been killed regionally by vehicle traffic (McLennan & Asiimwe 2016, McLennan et al. 2021). Human-wildlife conflict presents another major threat to chimpanzee survival (McLennan & Hill 2012), and chimpanzees have been killed by illegal mantraps set in order to discourage crop feeding (McLennan et al. 2012, Cibot et al. 2019). Disease risk also threatens chimpanzees; this risk includes respiratory diseases (Tusiime et al. 2024) as well as gastrointestinal parasites (McLennan et al. 2017; 2018, Cibot et al. 2021)

Table 3. Threats to apes reported for Budongo-Bugoma corridor

Category	Specific threats	Threat level	Description	Year of threat
10 Geological events		Absent
1 Residential & commercial development	1.2 Commercial & industrial areas	High (more than 70% of population affected)	Hoima City - a fast-expanding urban centre, which was elevated from town to city status in 2020 - is situated in the centre of the Budongo-Bugoma corridor. The ranges of at least two chimpanzee communities reach the peri-urban outskirts of the city, including areas earmarked for industrialisation (McLennan et al. 2021).	2020-Ongoing (2024)
2 Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	High (more than 70% of population affected)	Habitat loss due to agricultural expansion for commercial and subsistence farming, leading to increased human-chimpanzee conflict (McLennan et al. 2012; McLennan & Hill 2015; Oxley 2019).	2012-Ongoing (2024)
2 Agriculture & aquaculture	2.2 Wood & pulp plantations	High (more than 70% of population affected)	Habitat loss due to expansion of exotic timber plantations (McLennan et al. 2021).	2020-Ongoing (2024)
3 Energy production & mining	3.1 Oil & gas drilling	High (more than 70% of population affected)	Pipeline being built in the area, leading to development of infrastructure and associated mounting anthropogenic pressures on chimpanzees (McLennan et al. 2021).	2020-Ongoing (2024)
4 Transportation & service corridors	4.1 Roads & railroads	High (more than 70% of population affected)	Risk of vehicle collision as chimpanzees frequently have to cross roads; further development of roads in connection to the construction of the oil pipeline (McLennan et al. 2021). At least two chimpanzees are known to have been killed in collisions with vehicles while crossing roads (McLennan & Asiimwe 2016, McLennan et al. 2021).	2020-Ongoing (2024)
5 Biological resource use	5.3 Logging & wood harvesting	High (more than 70% of population affected)	Unregulated commercial logging, i.e. local landowners sell trees to timber dealers, and then clear the land for farming. Residents also cut trees for firewood and to produce charcoal (BCCP, unpublished data).	2020-Ongoing (2024)
6 Human intrusions & disturbance	6.3 Other human disturbances	High (more than 70% of population affected)	Chimpanzees throughout the Budongo-Bugoma corridor encounter people working in gardens and agricultural fields, or engaged in other work activities (e.g. house building, carpentry, cattle herding), on a daily basis.	2020-Ongoing (2024)
7 Natural system modifications	7.3 Other ecosystem modifications	High (more than 70% of population affected)	Reduced options for female dispersal caused by clearance of riparian forest corridors (McCarthy et al. 2018).	2018-Ongoing (2024)
8 Invasive & other problematic species, genes & diseases	8.4 Pathogens	High (more than 70% of population affected)	Chimpanzees throughout the region have daily contact with humans and domestic animals, and are at risk from respiratory diseases and gastrointestinal parasites (Cibot et al. 2021, McLennan et al. 2017, 2018, Tusiime et al. 2024).	2017-Ongoing (2024)
9 Pollution	9.3 Agricultural & forestry effluents	High (more than 70% of population affected)	Water sources in the range of at least 1 chimpanzee community are severely contaminated with waste effluent (sugarcane molasses) from a large commercial distillery (McLennan et al. 2021). Local farmers commonly use inorganic herbicides and pesticides; potential impacts on the chimpanzees are not yet known.	2020-Ongoing (2024)
12 Other threat	12.1 Other threat	High (more than 70% of population affected)	Snare and trap injuries can result in lethal injuries. Traps are sometimes placed by farmers around agricultural gardens to reduce crop losses (McLennan 2008, McLennan et al. 2012, Cibot et al. 2019). 19% of individuals of one community in the corridor (Mairirwe community) exhibit limb deformities consistent with injuries caused by wire snares or steel traps (BCCP, unpublished data).	2008-Ongoing (2024)
11 Climate change & severe weather		Unknown

IUCN Threats list

Conservation activities

The Bulindi Chimpanzee & Community Project (BCCP) was established in 2015 with the main goal of halting ongoing deforestation and safeguarding habitat for resident chimpanzees in the Budongo-Bugoma corridor. BCCP links conservation of chimpanzees and their habitat to improved livelihoods for local people. The project partners with water nonprofits to construct village boreholes, promotes tree planting and agroforestry, provides fuel-efficient stoves, supports women’s health and livelihoods, implements education outreach in local schools, and sponsors schoolchildren of forest-owning families that preserve their forests (BCCP 2024). As of 2024, BCCP’s programs reach local villages throughout the Budongo-Bugoma landscape. Other non-government organizations also working to conserve chimpanzees in the Budongo-Bugoma corridor include the Jane Goodall Institute-Uganda, Wildlife Conservation Society, Flora & Fauna, and Chimpanzee Trust.

Table 4. Conservation activities reported for Budongo-Bugoma corridor

Category	Specific activity	Description	Implementing organization(s)	Year of activity
1 Development impact mitigation	1.4 Farm more intensively and effectively in selected areas and spare more natural land	BCCP has a coffee growing alternative livelihood project, providing coffee seedlings to farmers and guidance on 'best practice' coffee farming. In contrast to other cash crops (e.g. tobacco, rice and sugarcane), coffee is considered more 'chimpanzee friendly' because farmers establish coffee in existing gardens rather than cutting new gardens in forest or wetlands, and chimpanzees and other primates rarely eat from the coffee plant. Coffee matures after 2-3 years and the harvest can contribute significantly to household incomes (BCCP 2020, 2024).	Bulindi Chimpanzee and Community Project	2020-Ongoing (2024)
3 Species health	3.1 Wear face-masks to avoid transmission of viral and bacterial diseases to primates	Strict use of face masks and hand sanitisers by researchers and local 'Chimpanzee Monitors' entering forest areas, and when in proximity to chimpanzees; bespoke health and hygiene training provided to all staff (BCCP, unpublished data).	Bulindi Chimpanzee and Community Project	2020-Ongoing (2024)
4 Education & awareness	4.1 Educate local communities about apes and sustainable use	BCCP implements a conservation outreach programme in villages throughout the Budongo-Bugoma corridor. The aim is to provide accurate information to residents about chimpanzees and related environmental issues, answer questions and address misconceptions, mitigate conflicts, and directly address concerns people have about living near chimpanzees. BCCP provides conservation outreach for schoolchildren in local schools. The program aims to foster interest, empathy, and understanding of chimpanzees, interest in tree planting and awareness of importance of natural forest, and promotes 'safe' behavior for children encountering chimpanzees (BCCP 2020, 2024).	Bulindi Chimpanzee and Community Project	2020-Ongoing (2024)
5 Protection & restoration	5.6 Habitat restoration	BCCP has an extensive tree planting program in the Budongo-Bugoma corridor, including raising indigenous tree species for habitat enrichment, coffee as an alternative livelihood for farmers, and fast-growing timber species for household woodlots. The woodlots provide local households with an alternative source of wood and alternative income from timber sales, reducing reliance on remaining natural forest (BCCP 2020).	Bulindi Chimpanzee and Community Project	2020-Ongoing (2024)
5 Protection & restoration	5.4 Create natural habitat patches (including corridors)	BCCP works with local landowners to increase their capacity to conserve fragments of natural forest that offer critical remaining habitat for chimpanzees. Assistance includes sponsoring schoolchildren, alternative livelihoods support, and establishment of formal associations of private forest owners.	Bulindi Chimpanzee and Community Project	2020-Ongoing (2024)
7 Economic & other incentives	7.1 Provide monetary benefits to local communities for sustainably managing their forest and its wildlife (e.g., REDD, alternative income, employment)	BCCP sponsors women’s business savings programs to boost family incomes via environmentally-friendly household projects (BCCP 2020, 2024).	Bulindi Chimpanzee and Community Project	Ongoing (2020)
7 Economic & other incentives	7.2 Provide non-monetary benefits to local communities for sustainably managing their forest and its wildlife (e.g., better education, infrastructure development)	BCCP installs village water boreholes, builds energy stoves, and sponsors schoolchildren from forest-owning families (BCCP 2020, 2024). Woodlots provided for local households provide an alternative source of wood and alternative income from timber sales, reducing reliance on remaining natural forest (BCP 2020).	Bulindi Chimpanzee and Community Project	Ongoing (2020)

Conservation activities list (Junker et al. 2017)

Challenges

Ongoing habitat conversion (clearance of riparian forest and wetlands) for commercial and subsistence agriculture, leading to high levels of 'conflict' between chimpanzees and farmers (McLennan 2008, McLennan & Hill 2015). Chimpanzee communities throughout the Budongo-Bugoma corridor habitually feed on agricultural crops (McLennan et al. 2020, McCarthy & Lester 2021), which leads to growing intolerance towards chimpanzees, including occasional trappings and retaliatory killings (McLennan & Hill 2012, McLennan et al. 2012). Infrastructural development (e.g. road upgrades, urbanisation) is driving rapid changes to the chimpanzee habitat (McLennan et al. 2021).

Table 5. Challenges reported for Budongo-Bugoma corridor

Challenges	Specific challenges	Source
2 Resources and capacity	2.3 General lack of funding	McLennan, pers. comm.
4 Institutional support	4.1 Lack of law enforcement	McLennan 2008
4 Institutional support	4.2 Lack of government support	McLennan 2008

Enablers

Table 6. Enablers reported for Budongo-Bugoma corridor

Enablers	Specific enablers	Source	Year(s)
1 Site management
2 Resources and capacity
3 Engaged community
4 Institutional support
5 Ecological context
6 Safety and stability

Research activities

Six chimpanzee communities within the Budongo-Bugoma corridor are currently subjects of ongoing research and monitoring (BCCP 2024), including the long-term Bulindi Area study community (e.g. McLennan et al. 2019b, Satsias et al. 2022). Other communities under study or long-term monitoring include the Kasokwa-Kityedo Forest Project (Reynolds et al. 2003), Kasongoire (Oxley 2019), Wagaisa (McCarthy et al. 2017, McLennan et al. 2021) and Mairirwe (McLennan et al. 2019a) communities. Locations of some of these communities are shown in McCarthy et al. (2015, 2018).

Male chimpanzee in a pine tree in the Wagaisa area (photo by Jack Lester)
Male chimpanzees eating commercially farmed sugarcane, Wagaisa area (Photo by Bulindi Chimpanzee & Community Project)
Chimpanzee nests in exotic eucalyptus trees (Photo by Matthew McLennan)

Documented behaviours

Table 7. Behaviours documented for Budongo-Bugoma corridor

Behavior	Source
Eucalyptus bark eating / cambium eating	McCarthy et al. 2017; McLennan et al. 2021
Nesting in introduced tree species (eucalyptus, cocoa, guava, Caribbean pine)	McCarthy et al. 2017; McLennan et al. 2021
Making ground nests	McCarthy et al. 2017
Crop feeding	Reynolds et al. 2003, McLennan 2008, Oxley 2019, McLennan et al. 2020, McLennan et al. 2021, McCarthy & Lester 2021
Road crossing	McLennan et al. 2021
Honey digging with stick tools	McLennan et al. 2019a, 2019b
Food sharing (agricultural crops)	BCCP, unpublished data

Exposure to climate change impacts

External links

Bulindi Chimpanzees Facebook

Bulindi National Geographic

Relevant datasets

References

BCCP (2020). 2019 Annual Report to Friends & Funders. Bulindi Chimpanzee and Community Project, Hoima, Uganda.
BCCP (2024). 2024 Progress Report to Friends & Funders. Bulindi Chimpanzee and Community Project, Hoima, Uganda.
Cibot, M., Le Roux, S., Rohen, J., & McLennan, M.R. (2019). Death of a trapped chimpanzee: survival and conservation of great apes in unprotected agricultural areas of Uganda. African Primates 13, 47-56.
Cibot, M., McLennan, M. R., Kváč, M., Sak, B., Asiimwe, C., & Petrželková, K. (2021). Sparse evidence for Giardia intestinalis, Cryptosporidium spp. and Microsporidia infections in humans, domesticated animals and wild nonhuman primates sharing a farm–forest mosaic landscape in Western Uganda. Pathogens, 10(8), 933. https://doi.org/10.3390/pathogens10080933
McCarthy, M. S., & Lester, J. D. (2021). Consumption of cultivated subterranean plant organs by chimpanzees in a human-dominated landscape. Behaviour, 159(2), 171-186. https://doi.org/10.1163/1568539X-bja10107
McCarthy, M. S., Lester, J. D., Howe, E. J., Arandjelovic, M., Stanford, C. B., & Vigilant, L. (2015). Genetic censusing identifies an unexpectedly sizable population of an endangered large mammal in a fragmented forest landscape. BMC Ecology, 15(1), 21. https://doi.org/10.1186/s12898-015-0052-x
McCarthy, M. S., Lester, J. D., & Stanford, C. B. (2017). Chimpanzees (Pan troglodytes) flexibly use introduced species for nesting and bark feeding in a human-dominated habitat. International Journal of Primatology, 38(2), 321-337. https://doi.org/10.1007/s10764-016-9916-y
McCarthy, M. S., Lester, J. D., Langergraber, K. E., Stanford, C. B., & Vigilant, L. (2018). Genetic analysis suggests dispersal among chimpanzees in a fragmented forest landscape in Uganda. American Journal of Primatology, 80(9), e22902. https://doi.org/10.1002/ajp.22902
McLennan, M.R. (2008). Beleaguered chimpanzees in the agricultural district of Hoima, Western Uganda. Primate Conservation 23, 45–54. https://doi.org/10.1896/052.023.0105
McLennan, M.R. & Asiimwe, C. (2016). Cars kill chimpanzees: case report of a wild chimpanzee killed on a road at Bulindi, Uganda. Primates 57, 377-388. https://doi.org/10.1007/s10329-016-0528-0
McLennan, M.R., Hasegawa, H., Bardi, M., & Huffman, M.A. (2017). Gastrointestinal parasite infections and self-medication in wild chimpanzees surviving in degraded forest fragments within an agricultural landscape mosaic in Uganda. PLoS ONE 12, e0180431. https://doi.org/10.1371/journal.pone.0180431
McLennan, M.R. & Hill, C.M. (2012). Troublesome neighbours: changing attitudes towards chimpanzees (Pan troglodytes) in a human-dominated landscape in Uganda. Journal for Nature Conservation 20, 219-227. https://doi.org/10.1016/j.jnc.2012.03.002
McLennan, M.R. & Hill, C.M. (2015). Changing agricultural practices and human-chimpanzee interactions: tobacco and sugarcane farming in and around Bulindi, Uganda. In: Arcus Foundation, ed. State of the Apes Volume II: Industrial Agriculture and Ape Conservation. Cambridge, UK: Cambridge University Press.
McLennan, M. R., Hintz, B., Kiiza, V., Rohen, J., Lorenti, G. A., & Hockings, K. J. (2021). Surviving at the extreme: chimpanzee ranging is not restricted in a deforested human‐dominated landscape in Uganda. African Journal of Ecology, 59(1), 17-28. https://doi.org/10.1111/aje.12803
McLennan, M. R., Hyeroba, D., Asiimwe, C., Reynolds, V., & Wallis, J. (2012). Chimpanzees in mantraps: lethal crop protection and conservation in Uganda. Oryx, 46(4), 598-603. https://doi.org/10.1017/S0030605312000592
McLennan, M.R., Lorenti, G.A., Mugenyi, S., Muganzi, J., & Rohen, J. (2019a). Digging for clues: stick tools used for honey digging in a second community of ‘forest fragment chimpanzees’ outside the Budongo and Bugoma Forests, Uganda. Revue de Primatologie, 10, https://doi.org/10.4000/primatologie.6718
McLennan, M. R., Lorenti, G. A., Sabiiti, T., & Bardi, M. (2020). Forest fragments become farmland: dietary response of wild chimpanzees (Pan troglodytes) to fast‐changing anthropogenic landscapes. American Journal of Primatology, 82(4), e23090. https://doi.org/10.1002/ajp.23090
McLennan, M.R., Mori, H., Mahittikorn, A., Prasertbun, R., Hagiwara, K., & Huffman, M.A. (2018). Zoonotic enterobacterial pathogens detected in wild chimpanzees. Ecohealth 15, 143-147. https://doi.org/10.1007/s10393-017-1303-4
McLennan, M.R., Rohen, J., Satsias, Z., Sabiiti, T., Baruzaliire, J.-M., & Cibot, M. (2019b). ‘Customary’ use of stick tools by chimpanzees in Bulindi, Uganda: update and analysis of digging techniques from behavioural observations. Revue de Primatologie, 10, https://doi.org/10.4000/primatologie.6706
Oxley, A. S. (2019). Great ape conservation in the matrix: Investigating the socio-ecological responses of chimpanzees living in a forest–farm mosaic, Uganda. Oxford Brookes University, UK (unpublished doctoral dissertation)
Plumptre, A.J. et al. (2010). Eastern Chimpanzee (Pan troglodytes schweinfurthii): Status Survey and Conservation Action Plan, 2010-2020. IUCN, Switzerland.
Reynolds, V., Wallis, J., & Kyamanywa, R. (2003). Fragments, sugar, and chimpanzees in Masindi District, western Uganda. In L. K. Marsh (Ed.), Primates in fragments: Ecology and conservation (pp. 309–320). USA: Springer.
Satsias, Z.M., Silk, M.J., Hockings, K.J., Cibot, M., Rohen, J., & McLennan, M.R. (2022). Sex-specific responses to anthropogenic risk shape wild chimpanzee social networks in a human-Impacted landscape. Animal Behaviour, 186, 29–40. https://doi.org/10.1016/j.anbehav.2022.01.016
Tusiime, P., Weary, T., Pappas, T., Tuhaise, S., Akankwasa, J.W., Sempebwa, D., Otali, E., Asiimwe, C., McLennan, M.R., Kalema-Zikusoka, G., Ross, E., Gern, J., & Goldberg, T. (2024). Pediatric respiratory pathogens circulate in children and adults in communities near susceptible wild great ape populations in Uganda. Transboundary and Emerging Diseases, 2024(1), 1771163. https://doi.org/10.1155/2024/1771163
Twongyirwe, R., Bithell, M., Richards, K. S., & Rees, W. G. (2015). Three decades of forest cover change in Uganda’s Northern Albertine Rift Landscape. Land Use Policy, 49, 236-251. https://doi.org/10.1016/j.landusepol.2015.07.013

Page created by: Matthew McLennan, Maureen McCarthy & Jack Lester Date: 2021-01-14

Page updated by: Matthew McLennan Date: 45649.0

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