Tonkoli Forest Reserve

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Summary

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• Western chimpanzees (Pan troglodytes verus) are present in Tonkoli Forest Reserve.
• The population size is unknown.
• The chimpanzee population trend is decreasing.
• The site has a total size of 71 km².
• Key threats to chimpanzees are logging, hunting and loss of habitat due to agricultural expansion.
• Conservation activities are not reported.

Site characteristics

The site was established as a forest reserve in 1926 (WDPA).

Table 1. Basic site information for Tonkoli Forest Reserve

Species	Pan troglodytes verus
Area	71 km²
Coordinates	Lat: 8.885335 , Lon: -11.493043
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

During a national survey in 2009, interviews were conducted in 24 communities in and around the Tonkoli Reserve; 8 reported the presence of chimpanzees, and 16 communities reported having no chimpanzees in the vicinity (Brncic et al. 2010). Several people reported that chimpanzees were present around their community before the war. Based on interviews, they may still be present in the southeastern part of the reserve (Brncic et al. 2010).

Table 2. Ape population estimates reported for Tonkoli 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 verus	2009	Present				Tonkoli Forest Reserve	Interviews		Brncic et al. 2010		SLE0002, SLE0003 SLE0004, SLE0014, SLE0015, SLE0017, SLE0018, SLE0021, SLE0024, SLE0025, SLE0026, SLE0029, SLE0032, SLE0036, SLE0037

Sampling methods Analytical frameworks

Threats

The main threats to chimpanzees in the site, as reported by local communities during a 2009 interview survey, include hunting, farming, logging, and civil war (1991-20020). Many people reported that chimpanzees were present before the war, but not seen now for some time. The site was used extensively by rebels during the war. Much of the forest has been damaged or lost as a consequence; chimpanzees have been largely hunted or driven out from the area. In addition, much of the forest has been cleared for agriculture (Brncic et al. 2010).

Table 3. Threats to apes reported for Tonkoli 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)	A large portion of the forest appears to have been cleared for crops such as rice and pepper (Brncic et al. 2010).	Ongoing (2010)
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 2010 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 severely degraded the forest. A logging company appears to have a concession inside the reserve (Brncic et al. 2010).	Ongoing (2010)
6 Human intrusions & disturbance	6.2 War, civil unrest & military exercises	High (more than 70% of population affected)	The decline in chimpanzee population was noticeable to local communities as a result of war and increased severity of related threats, such as hunting and logging (Brncic et al. 2010).	1991-2002

Threats

Conservation activities

Table 4. Conservation activities reported for Tonkoli Forest Reserve

Category	Specific activity	Description	Implementing organization(s)	Year of activity
5 Protection & restoration	5.2 Legally protect ape habitat	The site is a forest reserve.		1926-Ongoing (2026)

Conservation activities

Challenges

Table 5. Challenges reported for Tonkoli Forest Reserve

Challenges	Specific challenges	Source	Year(s)
	Not reported

Challenges

Enablers

Table 6. Enablers reported for Tonkoli 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

Documented behaviours

Table 7. Behaviours documented for Tonkoli 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 Tonkoli 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]	25.6	26.8	26.6	26.8	28
Annual precipitation [mm]	2263	2210	2281	2278	2344
Max no. consecutive dry days (per year)	34.3	37.6	38.5	41.3	42.5
No. days with heavy precipitation (per year)	5.6	5.9	5.9	6.2	7.4

Table 9. Projected exposure of apes to extreme climate impact events in Tonkoli 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	5	0.15	3.5	0.15	4.5	0.15	8.5	0.35
Drought	0	0	0	0	0	0	0	0
Heatwave	8.5	100	7.5	100	9.5	100	8	100
River flood	0	0	0.5	1.07	0.5	2.08	2	2.6
Tropical cyclone	0	0	0	0	0.5	2.46	0	0
Wildfire	30	0.55	30	0.55	29	0.57	29	0.57

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  Precipitation anomaly in Tonkoli Forest Reserve

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  Temperature anomaly in Tonkoli Forest Reserve

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. 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), e0000345. doi:10.1371/journal.pclm.0000345

Page created by: APES Atlas Team Date: 2023-11-16