Sapo-Grebo-Krahn corridor
Summary
- 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 |
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 |
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 |
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