Lake Sonfon

West Africa > Sierra Leone > Lake Sonfon

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

Area	8 km²
Coordinates	9.249629, -11.499968
Designation
Habitat types	Savanna, subtropical/tropical moist lowland forest

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 in Lake Sonfon

Species	Year	Abundance estimate (95% CI)	Density estimate [ind./ km²] (95% CI)	Encounter rate (nests/km)	Area	Method	Source	Comments	A.P.E.S. database ID
Pan troglodytes verus	2009			Present	Lake Sonfon Forest Reserve	Interview survey	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 in Lake Sonfon

Category	Specific threats	Threat level	Quantified severity	Description	Year of threat
1. Residential & commercial development		Unknown
2. Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	Low		Habitat degradation due to farming activities (Brncic et al. 2010, Sesay et al. 2017).	2010-Ongoing (2017)
3. Energy production & mining	3.2 Mining & quarrying	High		Artisanal gold mining is the largest threat (Brncic et al. 2010, Sesay et al. 2017)	2010-Ongoing (2017)
4. Transportation & service corridors		Unknown
5. Biological resource use	5.1 Hunting & collecting terrestrial animals	High		Hunting was reported as a main threat during a 2009 interview survey in the area (Brncic et al. 2010).	Ongoing (2010)
	5.3 Logging & wood harvesting	High		Logging and subsequent agricultural activities have degraded the forest (Brncic et al. 2010); charcoal extraction (Sesay et al. 2017).	2010-Ongoing (2017)
6. Human intrusion & disturbance	6.2 War, civil unrest & military exercises	Present, but severity unknown		A decline in chimpanzee population was noticeable to local communities since the war (Brncic et al. 2010).	1991-2002
7. Natural system modifications		Unknown
8. Invasive & other problematic species, genes, diseases		Unknown
9. Pollution		Unknown
10. Geological Events		Absent
11. Climate change & severe weather		Unknown
12. Other options		Absent

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).

Table 4. Conservation activities in Lake Sonfon

Category	Specific activity	Description	Year of activity
1. Residential & commercial development	Not reported
2. Agriculture & aquaculture	Not reported
3. Energy production & mining	Not reported
4. Transportation & service corridors	Not reported
5. Biological resource use	Not reported
6. Human intrusion & disturbance	Not reported
7. Natural system modifications	Not reported
8. Invasive & other problematic species, genes, diseases	Not reported
9. Pollution	Not reported
10. Education & Awareness	Not reported
11. Habitat Protection	Not reported
12. Species Management	Not reported
13. Livelihood; Economic & Other Incentives	Not reported

Conservation activities list (Junker et al. 2017)

Challenges

Table 5. Challenges reported for Lake Sonfon

Challenge	Source
Not reported

Research activities

Documented behaviours

Table 6. Ape behaviors reported for Lake Sonfon

Behavior	Source
Not reported

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 completed by: A.P.E.S. Wiki team Date: 24/11/2023