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West Africa > Liberia > Sapo-Grebo-Krahn corridor

Summary

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Western chimpanzees (Pan troglodytes verus) are present in the corridor linking SNP and GKNP.
It has been estimated that 533 (CI: 248-1,147) individuals occur at the site.
The chimpanzee population trend is decreasing.
This proposed corridor after the 2019 survey has a total size of 1260.35 km².
Key threats to chimpanzees are poaching, mining and logging.
The area represents a potential corridor to link two highly valuable and fully protected areas in Liberia; it also makes up a significant portion of the Tai-Grebo-Krahn-Sapo (TGKS) corridor complex. The corridor partially falls into the Sapo-Grebo Corridor Key Biodiversity Area (KBA) and the Grebo Important Bird Area (IBA).

Site characteristics

The site is a proposed corridor to link two national parks (Sapo and Grebo-Krahn National Parks). It is located in the south-east of Liberia in River-Gee county. It hosts threatened species, such as the pygmy hippopotamus Hexaprotodon liberiensis and Jentink’s duiker Cephalophus jentinki, (WCF 2015, 2019), as well as the red colobus Piliocolobus badius and the lowland Bongo Tragelaphus eurycerus eurycerus (Junker unpubl. data).

Table 1. Basic site information for Sapo-Grebo-Krahn corridor

Area	1260.35 km²
Coordinates	5.55 N, 7.78 W
Designation	Proposed ecological corridor
Habitat types	Subtropical/tropical moist lowland forest, Rural gardens, Subtropical/tropical heavily degraded former forest, Subtropical/Tropical Moist Shrubland

IUCN habitat categories Site designations

Ape status

Two line transect surveys were carried out across the corridor by the WCF in collaboration with the FDA (WCF 2015, 2019). According to the results of these surveys, the chimpanzee density decreased significantly in this area from 2015-2019 (Tweh pers. comm. 2019).

Table 2. Great ape population estimates in Sapo-Grebo-Krahn corridor

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	2015	688 (354- 1,328)	0.401	3.69	Proposed corridor linking SNP and GKNP	Line transects (Distance)	WCF 2015	Survey effort was 103.17 km; nests, feeding signs and vocalizations recorded
Pan troglodytes verus	2019	533 (248- 1,147)	0.146	0.78	Proposed corridor linking SNP and GKNP	Line transects (Distance)	WCF 2019	Survey effort was 145.25 km; nests, feeding signs and vocalizations recorded

Threats

The teams of the nationwide survey (Tweh et al. 2014) found many poaching signs in the south eastern part of the corridor, including used cartridges, snares and poaching trails (Junker unpubl.). It has been observed that wood used for chewing sticks is collected around illegal camps (Tweh pers. obs.). Additionally, a large part of the corridor falls into a ratified logging concession (Junker et al. 2015) and a smaller proportion overlaps with illegally issued Private-Use Permits (PUP) for commercial logging. Private Use Permits were a type of logging license designed to allow private land owners to cut trees on their property, but which were reportedly subject to misuse by commercial logging companies. After investigations by Global Witness (Global Witness 2013) much public outcry and extensive media coverage, PUPs have now largely been rescinded (Johnson 2015). A considerable part of the proposed protected area is covered by Mineral Exploration Licenses (MEL) for gold and other base metals owned by Planet Minerals Ltd. and iron ore owned by Jonah Capital (BVI) Liberia Ltd. (Johnson 2015). MEL’s entail that after a proposed exploration program has been handed to the Minister of Land, Mines, and Energy, the company commences exploration (Wilson et al. 2017).

Table 3. Threats to great apes in Sapo-Grebo-Krahn corridor

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	Encounter rate: 0.5 human signs/km surveyed (WCF 2019)	Human signs include: artisanal mining/gold washing sites, signs of logging, pit sawing, mining prospection holes, hamlet by miners, farming	Ongoing (2019)
3. Energy production & mining	3.2 Mining & Quarrying	Low	Encounter rate: 0.5 human signs/km surveyed (WCF 2019)	Human signs include: artisanal mining/gold washing sites, signs of logging, pit sawing, mining prospection holes, hamlet by miners, farming	Ongoing (2019)
4. Transportation & service corridors		Unknown
5. Biological resource use	5.1 Hunting & collecting	Medium	Encounter rate: 2.8 hunting signs/km surveyed (WCF 2019)	Hunting signs include: gunshots, cartridges, traps, poacher’s trails, poacher’s camp	Ongoing (2019)
	5.3 Logging & Wood Harvesting	Low	Encounter rate: 0.5 human signs/km surveyed (WCF 2019)	Human signs include: artisanal mining/gold washing sites, signs of logging, pit sawing, mining prospection holes, hamlet by miners, farming	Ongoing (2019)
6. Human intrusions & disturbance		Unknown
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

No conservation activities have been reported.

Table 4. Conservation activities in Sapo-Grebo-Krahn corridor

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 intrusions & 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 Sapo-Grebo-Krahn corridor

Impediment	Source
Not reported

Research activities

Wildlife and human demography and social surveys have been conducted at the site (WCF 2015, 2019).

Documented behaviours

Table 6. Great ape behaviors reported for Sapo-Grebo-Krahn corridor

Behavior	Source
Not reported

References

Global Witness. (2013). Avoiding the Riptide: Liberia must Enforce its Forest Laws to Prevent a New Wave of Illegal and Destructive Logging Contracts. Global Witness.
Johnson S. 2015. Aggregated Biodiversity Offsets: A Roadmap for Liberia’s Mining Sector. Unpublished report by the World Bank Group (WBG) and Program On Forests (PROFOR).
Junker J, Boesch C, Freeman T, Mundry R, Stephens C, Kühl HS. 2015. Integrating wildlife conservation with conflicting economic land-use goals in a West African biodiversity hotspot. Basic and Applied Ecology: doi:10.1016/j.baae.2015.07.002.
WCF 2015, Final report: Survey of wildlife and anthropogenic threats in the Grebo-Krahn Corridor, south- eastern Liberia. Online: Wild Chimpanzee Foundation
WCF 2019, Final report: Survey of wildlife and anthropogenic threats in the Grebo-Krahn Corridor, south- eastern Liberia. Online: Wild Chimpanzee Foundation
Wilson STK, Wang H, Kabenge M, Qi X. 2017. The mining sector of Liberia: current practices and environmental challenges. Environmental Science and Pollution Research 24: 18711–18720.

Page completed by: A.P.E.S. Wiki Team Date: 06/11/2019

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