West Africa > Republic of Guinea > Bossou

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Summary

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Western chimpanzees (Pan troglodytes verus) are present in Bossou.
The last population estimate was 7 individuals.
The chimpanzee population trend is declining.
This site has a total size of 20 km².
Key threats to chimpanzees are isolation due to habitat destruction and fragmentation.
The following conservation activities were implemented: establishing a habitat corridor and environmental education.
Bossou is one of the longest-running research sites on chimpanzees.

Site characteristics

Bossou is a long-term research site in south-eastern Guinea located 6 km west of the foot of the Nimba mountains (Kormos et al. 2003). The site was established in 1976 by Sugiyama and colleagues from the Kyoto University Primate Research Institute in Japan (Sugiyama 1979). Prior, Kortlandt was the first researcher to study chimpanzees at Bossou in 1960, but continuous research has been ongoing since 1976 (Kormos et al. 2003). Research conducted at Bossou has contributed to the understanding of chimpanzee ecology and behavior through numerous studies as diverse as population dynamics, social structure, feeding behavior, grooming behavior, genetics, tool use (as detailed in Kormos et al. 2003, The chimpanzees of Bossou and Nimba 2019). In 2001 the Institut de Recherche Environnementale de Bossou was established to foster collaboration between the Guinean government and Japanese researchers (Kormos et al. 2003).

Only one chimpanzee community remains in the forest surrounding the village of Bossou and ranges in an area of about 20 km2 (Humle 2011). The area is characterized by agricultural areas, secondary forests, savanna and interspersed gallery forests (Sugiyama 1979). The site is not under any formal protection. It was identified as a priority site for conservation in the regional action plan for western chimpanzees (Kormos et al. 2003).

Table 1. Basic site information for Bossou

Species	Pan troglodytes verus
Area	20 km²
Coordinates	Lat: 7.65 , Lon: -8.49
Type of site	Non-protected area
Habitat types	Agricultural land, Subtropical/tropical heavily degraded former forest, Subtropical/tropical moist lowland forest, Savanna
Type of governance

Types of sites Governance types Habitat types

Ape status

Since the chimpanzee community at Bossou is habituated to the presence of researchers, exact population estimates have been recorded since the 1970s. From 1976 to 2003 chimpanzee abundance fluctuated around 20 individuals (Sugiyama 1981, Kormos et al. 2003, The chimpanzees of Bossou and Nimba 2019). In 2004 the size of the chimpanzee community started to decline and is now at 7 individuals (The chimpanzees of Bossou and Nimba 2019).

Table 2. Ape population estimates reported for Bossou

Species	Year	Abundance estimate (95% CI)	Survey area	Sampling method	Source	Comments
Pan troglodytes verus	2018	7.0	Bossou	Full count	The chimpanzees of Bossou and Nimba 2019
Pan troglodytes verus	2004	14.0	Bossou	Full count	The chimpanzees of Bossou and Nimba 2019
Pan troglodytes verus	1979-1980	20 (19-21)	Bossou	Full count	Sugiyama 1981
Pan troglodytes verus	1976	21.0	Bossou	Full count	Sugiyama 1979
Pan troglodytes verus	1967	17.0	Bossou	Full count	Sugiyama 1979	likely underestimate as chimpanzees were not yet habituated to human observers (Sugiyama 1979)

Sampling methods Analytical frameworks

Threats

The key threat to chimpanzees is the destruction and fragmentation of habitat which led to the complete isolation of the Bossou chimpanzee community from other chimpanzee groups. The last male chimpanzee migrated into the research group in 1982 (Hirata et al. 1998). In the 1980s other chimpanzee groups in the surrounding area have likely gone extinct (Hirata at el. 1998).

1,500 people live in the village of Bossou. During the civil war in Liberia in the 1990s there was a large influx of migrants from Liberia to Bossou, and the local population almost doubled leading to further deforestation (Matsuzawa et al. 2011a). During the outbreak of a flu-like respiratory disease in 2003 five chimpanzees died (Humle 2011 b). The local population is tolerant towards chimpanzees based on the belief that chimpanzees are reincarnation of their ancestors (Matsuzawa et al. 2011a). Consequently, chimpanzees are not hunted, nor have retaliatory killings as a result of crop raiding by chimpanzees been reported.

Table 3. Threats to apes reported for Bossou

Category	Specific threats	Threat level	Description	Year of threat
1 Residential & commercial development	1.1 Residential areas	Medium (30-70% of population affected)	humans live in close proximity chimpanzees, but do not hunt them (Matsuzawa et al. 2011a)	Ongoing (2011)
2 Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	High (more than 70% of population affected)	widespread agriculture (Hockings et al. 2012)	Ongoing (2012)
4 Transportation & service corridors	4.1 Roads & railroads	Medium (30-70% of population affected)	chimpanzees need to cross roads to move between habitat patches (Matsuzawa et al. 2011a)	Ongoing (2011)
5 Biological resource use	5.3 Logging & wood harvesting	High (more than 70% of population affected)	most of the forest has been destroyed or degraded, especially when many people moved to the area during the Liberian civil war (Matsuzawa et al. 2011a)	1989-2003
7 Natural system modifications	7.1 Fire & fire suppression	Low (up to 30% of population affected)	fire do occur in the area (Matsuzawa et al. 2011a)	Ongoing (2011)
8 Invasive & other problematic species, genes & diseases	8.4 Pathogens	Medium (30-70% of population affected)	outbreak of flu-like respiratory disease killing five chimpanzees (Humle 2011b)	2003

Threats

Conservation activities

Conservation activities focus on reestablishing habitat connectivity between Bossou and the Nimba mountains to end the isolation of the chimpanzee community (Hirata et al. 1998). In 1997 the [“Green Corridor Project” https://www.greencorridor.info/] started. To overcome the 10 km distance to the Nimba mountains a habitat corridor is being planted of a length of 4 km and 300m wide through savanna areas.

Conservation activities also include environmental awareness raising since 1993 through video screenings, pamphlets, educational material for schools and environmental education sessions at schools (Hirata et al. 1998, Humle 2011c). The research project also provided financial support to the construction of schools and latrines, and material donations to schools (e.g., books, benches etc. Humle 2011c).

After the outbreak of a respiratory disease in 2003, several measures preventing the spread of human diseases to chimpanzees were implemented: a minimum distance between chimpanzees and humans of 20 m, compulsory wear of a masks, reinforcement of guidelines on disposal of human waste and debris, promoting the construction and usage of latrines in villages, health screening of staff, researchers and tourists working with chimpanzees, and the requirement of up-to-date vaccination by people working with the chimpanzees (Humle 2011b).

Table 4. Conservation activities reported for Bossou

Category	Specific activity	Description	Year of activity
3 Species health	3.1 Wear face-masks to avoid transmission of viral and bacterial diseases to primates	since the outbreak of the respiratory disease all people observing chimpanzees have to wear masks (Humle 2011b)	2003-Ongoing (2011)
3 Species health	3.2 Keep safety distance to habituated apes	a minimum distance of 20 m is enforced (Humle 2011b)	2003-Ongoing (2011)
3 Species health	3.6 Ensure that researchers/tourists are up-to-date with vaccinations and healthy	up-to-date vaccinations are required (Humle 2011b)	2003-Ongoing (2011)
4 Education & awareness	4.1 Educate local communities about apes and sustainable use	video screenings, pamphlets, educational material for schools and environmental education sessions at schools (Hirata et al. 1998, Humle 2011c)	1993-Ongoing (2011)
5 Protection & restoration	5.6 Habitat restoration	the Green Corridor Project aims to reestablish habitat connectivity between Bossou and the Nimba mountains (Matsuzawa et al. 2011a)	1997-Ongoing (2011)
7 Economic & other incentives	7.2 Provide non-monetary benefits to local communities for sustainably managing their forest and its wildlife (e.g., better education, infrastructure development)	Financial support for the construction of schools and latrines, material donations to schools (Humle 2011c)	1999-Ongoing (2011)

Conservation activities

Challenges

Table 5. Challenges reported for Bossou

Challenges	Specific challenges	Source	Year(s)
	Not reported

Challenges

Enablers

Table 6. Enablers reported for Bossou

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

Research activities

Since 1976 research has been continuously conducted at Bossou covering a wide range of topics from ecology, demography and social organization, tool use, cognition, communication, culture, feeding behavior, genetics, and social behaviors (listed in more detail in Kormos et al. 2003, Matsuzawa et al. 2011b, The chimpanzees of Bossou and Nimba 2019). As chimpanzees at Bossou live in a landscape strongly impacted by anthropogenic activities, one focus of research activities was how chimpanzee are behaving in such a landscape, on crop-raiding behavior by chimpanzees and conflicts between chimpanzees and humans (e.g., Hockings et al. 2012, Hockings et al. 2010).

Documented behaviours

Table 7. Behaviours documented for Bossou

Category	Behavior	Observation type	Prevalence	Observation dates	Source	Habituation	Species	Comment
	Algae scooping				Humle et al. 2011
	Ant dipping				Matsuzawa & Humle 2011
	Branch shaking				Whiten et al. 1999
	Branch slapping				Whiten et al. 1999
	Buttress beating				Whiten et al. 1999
	Drinking palm wine				Hockings et al. 2015
	Hunting and meat eating				Sugiyama 1981
	Leaf clipping				Sugiyama 1981
	Leaf cushion				The chimpanzees of Bossou and Nimba 2019
	Leaf sponging for drinking water				Sugiyama 1981
	Medicinal uses of leaves				Matsuzawa & Yamakoshi 1996
	Nut cracking (palm nut)				Sugiyama 1981
	Pestle pounding				Matsuzawa & Humle 2011
	Stem pull-through				Whiten et al. 1999
	Stone throwing				Whiten et al. 1999
	Termite fishing				Whiten et al. 1999
	Wood pounding				Whiten et al. 1999

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 Bossou

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	26.1	26.1	26.2	27.3
Annual precipitation [mm]	1930	1955	1991	1998	2070
Max no. consecutive dry days (per year)	33.9	31.6	30.4	33	33.8
No. days with heavy precipitation (per year)	6	8	7.3	8.2	9.7

Table 9. Projected exposure of apes to extreme climate impact events in Bossou

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	7.5	5.96	6.5	5.96	7.5	5.96	17.5	5.96
Drought	0	0	0	0	0	0	0	0
Heatwave	7.5	100	5.5	100	6.5	100	6	100
River flood	0.5	0.08	1.75	0.88	2	1.46	4.5	1.39
Tropical cyclone	0	0	0	0	0	0	0	0
Wildfire	30	0.42	30	0.43	29	0.42	29	0.43

Precipitation anomaly in Bossou
Temperature anomaly in Bossou

External links

References

Hirata, S., Morimura, N., & Matsuzawa, T. (1998). Green passage plan (tree planting project) and environmental education using documentary videos at Bossou: A progress report. Pan African News, 5, 18–20.

Hockings, K. J., Yamakoshi, G., Kabasawa, A., & Matsuzawa, T. (2010). Attacks on local persons by chimpanzees in Bossou, Republic of Guinea: long‐term perspectives. American Journal of Primatology, 72(10), 887-896. doi:10.1002/ajp.20784

Hockings, K. J., Anderson, J. R., & Matsuzawa, T. (2012). Socioecological adaptations by chimpanzees, Pan troglodytes verus, inhabiting an anthropogenically impacted habitat. Animal Behaviour, 83(3), 801-810. doi:10.1016/j.anbehav.2012.01.002

Hockings, K. J., Bryson-Morrison, N., Carvalho, S., Fujisawa, M., Humle, T., McGrew, W. C., …, & Matsuzawa, T. (2015). Tools to tipple: ethanol ingestion by wild chimpanzees using leaf-sponges. Royal Society Open Science, 2(6), 150150. doi:10.1098/rsos.150150

Humle, T. (2011a). Location and ecology. In T. Matsuzawa, T. Humle, & Y. Sugiyama (Eds.), The chimpanzees of Bossou and Nimba. Springer. doi:10.1007/978-4-431-53921-6_3

Humle, T. (2011b). The 2003 epidemic of a flu-like respiratory disease at Bossou. In T. Matsuzawa, T. Humle, & Y. Sugiyama (Eds.), The chimpanzees of Bossou and Nimba. Springer. doi:10.1007/978-4-431-53921-6_33

Humle, T. (2011c). Environmental education and community development in and around Bossou. In T. Matsuzawa, T. Humle, & Y. Sugiyama (Eds.), The chimpanzees of Bossou and Nimba. Springer. doi:10.1007/978-4-431-53921-6_39

Humle, T., Yamakoshi, G., & Matsuzawa, T. (2011). Algae Scooping Remains a Puzzle. In Primatology Monographs (pp. 117-122). Springer Japan. doi:10.1007/978-4-431-53921-6_12

Kormos, R., et al. (2003). The Republic of Guinea. In R. Kormos, C. Boesch, M. I. Bakarr, & T. M. Butynski (Eds.), Status survey and conservation action plan. IUCN/SSC Primate Specialist Group.

Matsuzawa, T., & Yamakoshi, G. (1996). Comparison of chimpanzee material culture between Bossou and Nimba, West Africa. In A. E. Russon, K. A. Bard, & S. T. Parker (Eds.), Reaching into thought: The minds of the great apes. Cambridge University Press.

Matsuzawa, T., & Humle, T. (2011). Bossou: 33 Years. In Primatology Monographs (pp. 3-10). Springer Japan. doi:10.1007/978-4-431-53921-6_2

Matsuzawa, T., et al. (2011a). Green corridor project: Planting trees in the savanna between Bossou and Nimba. In T. Matsuzawa, T. Humle, & Y. Sugiyama (Eds.), The chimpanzees of Bossou and Nimba. Springer. doi:10.1007/978-4-431-53921-6_38

Matsuzawa, T., et al. (2011b). The chimpanzees of Bossou and Nimba. Springer. doi:10.1007/978-4-431-53921-6

Sugiyama, Y., & Koman, J. (1979). Social structure and dynamics of wild chimpanzees at Bossou, Guinea. Primates, 20(3), 323-339. doi:10.1007/bf02373387

Sugiyama, Y. (1981). Observations on the population dynamics and behavior of wild chimpanzees at Bossou, Guinea, in 1979–1980. Primates, 22(4), 435-444. doi:10.1007/bf02381236

The chimpanzees of Bossou and Nimba. (2019). Green Corridor Project. https://www.greencorridor.info/

Whiten, A., Goodall, J., McGrew, W. C., Nishida, T., Reynolds, V., Sugiyama, Y., …, & Boesch, C. (1999). Cultures in chimpanzees. Nature, 399(6737), 682-685. doi:10.1038/21415

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), 1-19. doi:10.1371/journal.pclm.0000345

Page created by: APES Atlas Team Date: 2019-07-19