Summary

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Western chimpanzees (Pan troglodytes verus) may be present in Lake Sonfon.
The population size is unknown.
The chimpanzee population trend is decreasing.
The site has a total size of 8 km².
Key threats to chimpanzees are mining, hunting, and habitat loss due to agriculture.
Conservation activities carried out by CSSL have focused on awareness raising and supporting livelihood alternatives.

Site characteristics

Lake Sonfon is located in the mountainous northeastern part of Sierra Leone, at an altitude of 549 m above sea level. The vegetation around the lake comprises open grassland, wooded savanna, forest, and farmbush. Seven small streams flow into the lake, which provide a water source for local communities. The lake is also important to local people in terms of traditional beliefs and ceremonies (Sesay et al. 2017, BirdLife International 2023, GNF). The site is an Important Bird Area (BirdLife International 2023). Western chimpanzees may be present around the lake; other large mammals in the Lake Sonfon environs include warthog, bay duiker, Maxwell’s duiker, bushbuck, buffalo, red river hog, and various monkeys (Brncic et al. 2010).

Table 1. Basic site information for Lake Sonfon

Species	'Pan troglodytes verus
Area	8 km²
Coordinates	Lat: 9.249629 , Lon: -11.499968
Type of site	Unknown
Habitat types	Savanna, Subtropical/tropical moist lowland forest
Type of governance

IUCN habitat categories Site designations

Ape status

Interviews were conducted around Lake Sonfon in 2009, which concluded that it does not contain a substantial chimpanzee population. The surrounding forest and woodland savanna may have several groups of chimpanzees (Brncic et al. 2010). Two of these groups were identified during the Bumbuna Hydroelectric Project Baseline Biodiversity Survey; the southernmost group was based near Worowaya ranging to the Seli River, comprising 8-16 individuals. A second group was located northeast of the Sel- Mawoloho confluence, comprising 6-9 individuals (Brncic et al. 2010). During a camera trap survey in 2016 chimpanzees were encountered at the site, though not on the camera traps (Sesay et al. 2016).

Table 2. Ape population estimates reported for Lake Sonfon

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	2009	Present				Lake Sonfon Forest Reserve	Interviews		Brncic et al. 2010
Pan troglodytes verus	2016	Present				Lake Sonfon Forest Reserve	Camera trap		Sesay et al. 2017	Chimpanzees were observed, but not on the camera traps

Threats

During a 2009 survey, people from nearby villages identified mining, hunting, and farming activities as causing a decline in the chimpanzee population since the war (Brncic et al. 2010). The lake itself and the immediate environs are threatened primarily by artisanal gold mining. A significant amount of mining activity was seen at the lake and its surroundings, which is likely to reduce water quality, increase wildlife exploitation and increase forest clearance (Brncic et al. 2010).

Table 3. Threats to apes reported for Lake Sonfon

Category	Specific threats	Threat level	Description	Year of threat
10 Geological events		Absent
12 Other threat		Absent
3 Energy production & mining	3.2 Mining & quarrying	High (more than 70% of population affected)	Artisanal gold mining is the largest threat (Brncic et al. 2010, Sesay et al. 2017)	2010-Ongoing (2017)
5 Biological resource use	5.1 Hunting & collecting terrestrial animals	High (more than 70% of population affected)	Hunting was reported as a main threat during a 2009 interview survey in the area (Brncic et al. 2010).	Ongoing (2010)
5 Biological resource use	5.3 Logging & wood harvesting	High (more than 70% of population affected)	Logging and subsequent agricultural activities have degraded the forest (Brncic et al. 2010); charcoal extraction (Sesay et al. 2017).	2010-Ongoing (2017)
2 Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	Low (up to 30% of population affected)	Habitat degradation due to farming activities (Brncic et al. 2010, Sesay et al. 2017).	2010-Ongoing (2017)
6 Human intrusions & disturbance	6.2 War, civil unrest & military exercises	Present (unknown severity)	A decline in chimpanzee population was noticeable to local communities since the war (Brncic et al. 2010).	1991-2002
1 Residential & commercial development		Unknown
4 Transportation & service corridors		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

Since 2011, Friends of the Environment and Culture (FOTEC) has worked towards protecting the flora and fauna at the site (GNF). The Conservation Society of Sierra Leone has also conducted conservation activities in the area, including awareness raising and support for alternative livelihood programs (CSSL).

Challenges

Table 5. Challenges reported for Lake Sonfon

Challenges	Specific challenges	Source	Year(s)
	Not reported

Enablers

Table 6. Enablers reported for Lake Sonfon

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

Documented behaviours

Table 7. Behaviours documented for Lake Sonfon

Behavior	Source
Not reported

Exposure to climate change impacts

External links

Relevant datasets

References

Brncic, T.M., Amarasekaran,B. & McKenna,A. 2010. Final Report of the Sierra Leone National Chimpanzee Census Project. Tacugama Chimpanzee Sanctuary, Freetown, Sierra Leone.

BirdLife International (2023) Important Bird Area factsheet: Lake Sonfon and environs. Downloaded from http://datazone.birdlife.org/site/factsheet/lake-sonfon-and-environs-iba-sierra-leone on 04/12/2023.

Sesay, P. B. Abdulai Duada, A. D. Momoh Bai-Sesay M. B., Havery, S. J., Ashpole, J., Hillers, A. & Oppel, S. (2017) Report on the biodiversity of Lake Sonfon, Sierra Leone. Report to African Bird Club & Bread for the World.

Page created by: A.P.E.S. Wiki team Date: NA

Lake Sonfon

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