Yelleh-Sorbengi Forest and Mai-Mokombo Forest

West Africa > Sierra Leone > Yelleh-Sorbengi Forest and Mai-Mokombo Forest

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Summary

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• Western chimpanzees (Pan troglodytes verus) are present in Yelleh-Sorbengi Forest and Mai-Mokombo Forest.
• The population size is unknown.
• The chimpanzee population trend is unknown.
• The site has a total size of 50 km².
• Key threats to chimpanzees are habitat destruction and fragmentation, leading to chimpanzee-human conflict.
• Conservation activities have focused on education, livelihood support, and biomonitoring.

Swamp on the edge of Yelleh forest © TCP

Site characteristics

The Yelleh-Sorbengi Forest (YSF) and Mai-Mokombo Forest (MMF) are in the South East of Moyamba District, Sierra Leone. The sites are located on the shores of the Bagru creek and the Sherbro river. The area includes five small settlements: Mobondah, Yelleh, Sorbengi, Mai, and Mokombo. The two forest blocks are separated by an area of land confirmed through research as a corridor for the movement of chimpanzees and other wildlife known to exist in the area. The corridor area and the core area of the two forests comprise a matrix of vegetation types and features. Vegetation types in the area include: mangroves, primary and secondary growth forest, swamps, grassy savannah, wild oil palm and agricultural lands. The two forests cover approximately 3 sq.km and the swamp/mangrove ecosystems approximately 50 sq.km. The mangroves are part of the Marine Protected Area Shebro River Estuary. The mangroves are categorised among one of the Marine Protected Areas - Shebro River Estuary in Sierra Leone.

Table 1. Basic site information for Yelleh-Sorbengi Forest and Mai-Mokombo Forest

Species	'Pan troglodytes verus
Area	50 km²
Coordinates	Lat: 7.770640 , Lon: -12.549755
Type of site	Non-protected area (Community Forest)
Habitat types	Subtropical/tropical moist lowland forest, Subtropical/tropical swamp forest, Savanna
Type of governance

IUCN habitat categories Site designations

Ape status

Conservation activities involving the use of camera traps and reconnaissance walks have revealed and confirmed evidence of the presence of chimpanzee thriving at the sites through direct capture on camera traps in three successive years: 2016, 2018 and 2019, and indirect signs (nests, trail, feeding remain on fruits and oil palm tops) encountered during the camera trap survey periods (Garriga & Kanneh 2022). Density and abundance estimates were not provided for all three studies. Reported so far are: capture locations of chimpanzees on camera traps and the identification of chimpanzee individuals based on facial and body features as well as individual characteristics such as injuries, and estimated their number, gender. On one event of camera capture of the species, the maximum numbers reported of different individuals were 8 individuals (2016), 5 individuals (2018) and 4 individuals (2019) (Garriga & Kanneh 2022).

Table 2. Ape population estimates reported for Yelleh-Sorbengi Forest and Mai-Mokombo Forest

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 verus	2016					YSF and MMF	Camera trap, Reconnaissance walk		Garriga 2016, 2018 and 2019	Camera trap and reconnaissance walks
Pan troglodytes verus	2018					YSF and MMF	Camera trap, Reconnaissance walk		Garriga 2016, 2018 and 2019	Camera trap and reconnaissance walks
Pan troglodytes verus	2019					YSF and MMF	Camera trap, Reconnaissance walk		Garriga 2016, 2018 and 2019	Camera trap and reconnaissance walks

Threats

Threats to the conservation of the species are limited at this site. The main threat is the reduction and disappearance of suitable habitats for their movements and survival mainly due to deforestation from slash and burn agriculture for cassava, rice and groundnut cultivation in the area. This is gradually leaving the chimpanzee population vulnerable to human conflicts, as the remaining patch of chimpanzee habitats overlaps with human settlements and cultivated areas thereby resulting in first crop raiding and then human wildlife conflict where chimpanzees have been killed in the process (Garriga & Kanneh 2022).

Table 3. Threats to apes reported for Yelleh-Sorbengi Forest and Mai-Mokombo Forest

Category	Specific threats	Threat level	Description	Year of threat
10 Geological events		Absent
12 Other threat		Present (unknown severity)	Human-chimpanzee conflict due to habitat fragmentation, destruction and reduction (Garriga & Kanneh 2022).	Ongoing (2022)
1 Residential & commercial development		Unknown
2 Agriculture & aquaculture		Unknown
3 Energy production & mining		Unknown
4 Transportation & service corridors		Unknown
5 Biological resource use		Unknown
6 Human intrusions & disturbance		Unknown
7 Natural system modifications		Unknown
8 Invasive & other problematic species, genes & diseases		Unknown
9 Pollution		Unknown
11 Climate change & severe weather		Unknown

IUCN Threats list

Conservation activities

Table 4. Conservation activities reported for Yelleh-Sorbengi Forest and Mai-Mokombo Forest

Category	Specific activity	Description	Implementing organization(s)	Year of activity
2 Counter-wildlife crime	2.11 Implement monitoring surveillance strategies (e.g., SMART) or use monitoring data to improve effectiveness of patrols	Community bio-monitoring and forest patrols implemented by Tacugama (Garriga & Kanneh 2022).		2018- 2020
4 Education & awareness	4.1 Educate local communities about apes and sustainable use	Introduction of the Tacugama Kids Environmental Education Program (TKEEP) in two schools and regular training community bio-monitors (Garriga & Kanneh 2022).		2018- 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)	Livelihood support projects organized by Tacugama, including agricultural seed support (rice and groundnuts) and sustainable oyster farming (Garriga & Kanneh 2022).		2018- 2020
8 Permanent presence	8.1 Run research project and ensure permanent human presence at site	Research through camera trapping and reconnaissance walks implemented by Tacugama (Garriga & Kanneh 2022).		2018- 2020

Conservation activities list (Junker et al. 2017)

Challenges

Addressing the human-chimpanzee conflict is a serious challenge at this site with limited livelihood intervention for the local population at the conservation area. At present there is no ongoing conservation project to complement previous conservation efforts and promote continuity. Establishment and strengthening of local bylaws as the forest area is owned by the surrounding communities (Garriga & Kanneh 2022).

Table 5. Challenges reported for Yelleh-Sorbengi Forest and Mai-Mokombo Forest

Challenges	Specific challenges	Source	Year(s)
2 Resources and capacity	2.3 General lack of funding	Garriga & Kanneh 2022
3 Engaged community	3.1 General lack of community engagement or support	Garriga & Kanneh 2022

Enablers

Table 6. Enablers reported for Yelleh-Sorbengi Forest and Mai-Mokombo Forest

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

Camera trap survey in 2016, 2018 and 2019; biomonitoring initiated in 2018 and presently on hold due to lack of funds. Community needs assessment (compilation of community profile) through questionnaire surveys in 2016 and 2018 (Garriga & Kanneh 2022).

© TCP

Documented behaviours

High frequency of chimpanzees nesting on palm trees which is not common to other places. This is probably due to the widespread presence of palm trees within the landscape in Sierra Leone and not the same case in other parts of the country (Garriga 2019).

Table 7. Behaviours documented for Yelleh-Sorbengi Forest and Mai-Mokombo Forest

Behavior	Source
Nesting on palm trees	Garriga 2019

External links

Tacugama Chimpanzee Sanctuary

References

Garriga, R. & Kanneh, A. (2022, October 20-21). Sierra Leone. Regional workshop on IUCN APES wiki, Monrovia, Liberia.

Garriga R.M., 2019. Mobondah community conservation project Moyamba District, Sierra Leone camera trap surveys. Report, Tacugama Chimpanzee Sanctuary, Freetown Sierra Leone, 27p.

Page created by: Rosa M. Garriga & Ambrose Bockarie Kanneh Date: NA