Summary

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Nigeria-Cameroon Chimpanzee (Pan troglodytes ellioti) are present in Lake Barombi Mbo Forest Reserve.
The population size is unknown.
The chimpanzee population trend is unknown.
The site has a total size of 8.5 km².
Key threats to chimpanzees are logging, hunting, encroachment due to agricultural expansion, and uncontrolled harvesting of terrestrial plants.
Conservation activities are not documented.
The site is designated as a Ramsar site and features Lake Barombi, well-known for its high density of endemic species.

Site characteristics

The Lake Barombi Forest Reserve is located in eastern Cameroon and covers an area of over 850 ha. The site is named after an oval lake 2.5 km in diameter and 110 m deep, lying in a crater with a slope of 150 m at its highest point, and surrounded by tropical forest (Eno Nku 2004). The lake is famous among biologists for the occurrence of 12 endemic fish species, making it one of the places with the highest densities of endemic species per area in the world (Ramsar 2006). The site is also important due to the presence of freshwater sponges, one of which (Corvospongilla thysi) is also endemic. The lake is an important sacred site to the Barombi Mbo People and also used for fishing, transport, and farming of the surrounding land (Ramsar 2006). It is also a source of clean water for the metropolis of Kumba and its surrounding (Ramsar 2006). The site was designated as a Ramsar site in 2006.

Table 1. Basic site information for Lake Barombi Mbo Forest Reserve

Species	Pan troglodytes ellioti
Area	8.5 km²
Coordinates	Lat: 4.669490 , Lon: 9.382303
Type of site	Protected area (Forest Reserve)
Habitat types	Subtropical/tropical moist lowland forest
Type of governance

Types of sites Governance types Habitat types

Ape status

Vocalisation documented during a recce survey (Eno Nku 2004).

Table 2. Ape population estimates reported for Lake Barombi Mbo Forest Reserve

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 ellioti	2004	Present				Lake Barombi Mbo Forest Reserve	Reconnaissance walk		Eno Nku (2004)	survey effort 4.5 km

Sampling methods Analytical frameworks

Threats

The competition for farmland in the area that began in 1989 led to the extensive conversion of forest into farmland (Eno Nku 2004). A stripe of forest still exists along the lakeshore to shield the farms, but behind is extended plantations. Other threats include timber extraction, hunting, farming, fuel wood collection, overfishing, use of pesticides, and uncontrolled harvesting of NTFPs (Eno Nku 2004).

Table 3. Threats to apes reported for Lake Barombi Mbo Forest Reserve

Category	Specific threats	Threat level	Description	Year of threat
2 Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	High (more than 70% of population affected)	Habitat encroachment due to agricultural expansion (Eno Nku 2004).	Ongoing (2004)
5 Biological resource use	5.1 Hunting & collecting terrestrial animals	High (more than 70% of population affected)	Unsustainable hunting (Eno Nku 2004).	Ongoing (2004)
5 Biological resource use	5.2 Gathering terrestrial plants	High (more than 70% of population affected)	Uncontrolled harvesting of NTFPs (Eno Nku 2004).	Ongoing (2004)
5 Biological resource use	5.3 Logging & wood harvesting	High (more than 70% of population affected)	Timber extraction and fuelwood collection (Eno Nku 2004).	Ongoing (2004)
9 Pollution	9.3 Agricultural & forestry effluents	Present (unknown severity)	Pesticide spraying of cocoa-trees (Ramsar 2006).	Ongoing (2006)

Threats

Conservation activities

Challenges

Table 5. Challenges reported for Lake Barombi Mbo Forest Reserve

Challenges	Specific challenges	Source	Year(s)
	Not reported

Challenges

Enablers

Table 6. Enablers reported for Lake Barombi Mbo Forest Reserve

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

Enablers

Research activities

Documented behaviours

Table 7. Behaviours documented for Lake Barombi Mbo Forest Reserve

Category	Behavior	Observation type	Prevalence	Observation dates	Source	Habituation	Species	Comment
	Not reported

Behaviours

Exposure to climate change impacts

As part of a study on the exposure of African great ape sites to climate change impacts, Kiribou et al. (2024) extracted climate data and data on projected extreme climate impact events for the site. Climatological characteristics were derived from observation-based climate data provided by the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP, www.isimip.org). Parameters were calculated as the average across each 30-year period. For 1981-2010, the EWEMBI dataset from ISIMIP2a was used. For the two future periods (2021-2050 and 2071-2099) ISIMIP2b climate data based on four CMIP5 global climate models were used. For future projections, two Representative Concentration Pathways (RCP) were used. RCP 2.6 is a scenario with strong mitigation measures in which global temperatures would likely rise below 2C. RCP 6.0 is a scenario with medium emissions in which global temperatures would likely rise up to 3C by 2100. For the number of days with heavy precipitation events, the 98th percentile of all precipitation days (>1mm/d) was calculated for the 1979-2013 reference period as a threshold for a heavy precipitation event. Then, for each year, the number of days above that threshold was derived. The figures on temperature and precipitation anomaly show the deviation from the mean temperature and mean precipitation for the 1979-2013 reference period.

The estimated exposure to future extreme climate impact events (crop failure, drought, river flood, wildfire, tropical cyclone, and heatwave) is based on a published dataset by Lange et al. 2020 derived from ISIMIP2b data. The same global climate models and RCPs as described above were used. Within each 30-year period, the number of years with an extreme event and the average proportion of the site affected were calculated (Kiribou et al. 2024).

Table 8. Estimated past and projected climatological characteristics in Lake Barombi Mbo Forest Reserve

Value	1981-2010	2021-2050, RCP 2.6	2021-2050, RCP 6.0	2071-2099, RCP 2.6	2071-2099, RCP 6.0
Mean temperature [C]	24.9	26	26	26.2	27.2
Annual precipitation [mm]	2605	2679	2721	2743	2691
Max no. consecutive dry days (per year)	36.9	29.4	30.6	27.1	31.6
No. days with heavy precipitation (per year)	6.1	7.1	7.1	8.1	7.6

Table 9. Projected exposure of apes to extreme climate impact events in Lake Barombi Mbo Forest Reserve

Type	No. of years with event (2021-2050, RCP 2.6)	% of site exposed (2021-2050, RCP 2.6)	No. of years with event (2021-2050, RCP 6.0)	% of site exposed (2021-2050, RCP 6.0)	No. of years with event (2070-2099, RCP 2.6)	% of site exposed (2070-2099, RCP 2.6)	No. of years with event (2070-2099, RCP 6.0)	% of site exposed (2070-2099, RCP 6.0)
Crop failure	4.5	0.1	4	0.18	2.5	0.1	2.5	0.05
Drought	0	0	0	0	0	0	0	0
Heatwave	5.5	100	8	100	5	100	7.5	100
River flood	2	0.56	1	0.8	1	1.93	4	1.31
Tropical cyclone	0	0	0	0	0	0	0	0
Wildfire	30	0.6	30	0.61	29	0.6	29	0.64

Precipitation anomaly in Lake Barombi Mbo Forest Reserve
Temperature anomaly in Lake Barombi Mbo Forest Reserve

External links

IUCN Regional Action Plan for the Conservation of the Nigeria-Cameroon Chimpanzee (Pan troglodytes ellioti)

References

Eno Nku, M. (2004). Large mammal reconnaissance surveys of Lake Barombi Mbo and Southern Banduku Forests Reserves, SW Province. Report to Wildlife Conservation Society & MINEF.

Ramsar (2006). Barombi Mbo Crater Lake. Online: https://rsis.ramsar.org/fr/ris/1643 link

Kiribou, R., Tehoda, P., Chukwu, O., Bempah, G., Kühl, H. S., Ferreira, J., …, & Heinicke, S. (2024). Exposure of African ape sites to climate change impacts. PLOS Climate, 3(2), 1-19. doi:10.1371/journal.pclm.0000345

Page created by: APES Atlas Team Date: 2022-02-28