Oba Hills Forest Reserve

West Africa > Nigeria > Oba Hills Forest Reserve

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Summary

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• Nigeria-Cameroon chimpanzees (Pan troglodytes ellioti) have been present in Oba Hills Forest Reserve.
• Chimpanzees are extinct or nearly extinct at the site.
• The population trend is unknown.
• The site has a total size of 68 km².
• Key threats to chimpanzees are logging, farming, hunting, and fires.
• Conservation activities are not reported.

Site characteristics

Located in the south-western state of Osun, in Nigeria, the site encompasses three hills and a valley in between.

Table 1. Basic site information for Oba Hills Forest Reserve

Species	Pan troglodytes ellioti
Area	68 km²
Coordinates	Lat: 7.783 , Lon: 4.117
Type of site	Protected area (Forest Reserve)
Habitat types	Agricultural land, Subtropical/tropical heavily degraded forest, Savanna, Shrubland, Subtropical/tropical swamp forest
Type of governance

Types of sites Governance types Habitat types

Ape status

Based on a survey in 2006, chimpanzees are likely to be extinct or nearly extinct in the area (Greengrass 2006). Only a chimpanzee-like vocalization was heard during the survey (Greengrass 2009). The last time local people reported seeing chimpanzees was in 2002 (Greengrass 2006), and in 1999 a dead chimpanzee was offered for sale in a nearby market (Oates et al. 2003 in Kormos et al. 2003).

Table 2. Ape population estimates reported for Oba Hills 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 ellioti	2006		0			Oba Hills Forest Reserve	Interviews, Reconnaissance walk		Greengrass 2006

Sampling methods Analytical frameworks

Threats

Taungya farming has spread throughout the bottom of the hills, and also halfway up the slopes (Greengrass 2006). In 2006, the hills were also being deforested and logged; scrubby vegetation growing back on the hills was frequently burnt, thus preventing regeneration (Greengrass 2006). In the western part of Oba Hills, there was once a large teak plantation, covering 12% of the total area, but since the plantation has been over-exploited, only coppices remain (Greengrass 2006).

Table 3. Threats to apes reported for Oba Hills 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)	All the land surrounding the three hills is subject to taungya farming, and the hills are being deforested; barely any forest is left (Greengrass 2006).	Ongoing (2006)
2 Agriculture & aquaculture	2.2 Wood & pulp plantations	Present (unknown severity)		Unknown
5 Biological resource use	5.1 Hunting & collecting terrestrial animals	High (more than 70% of population affected)	The chimpanzee population has been hunted likely to the point of extirpation; hunting of other species (e.g., duikers) continues (Greengrass 2006, Wahab 2016).	2006-Ongoing (2016)
7 Natural system modifications	7.1 Fire & fire suppression	High (more than 70% of population affected)	Repeated anthropogenic bush fires in the core of the reserve (Wahab 2016).	Ongoing (2016)

Threats

Conservation activities

Table 4. Conservation activities reported for Oba Hills Forest Reserve

Category	Specific activity	Description	Implementing organization(s)	Year of activity
5 Protection & restoration	5.2 Legally protect ape habitat	The forest reserve was established in 1955 (Wahab 2016).		1955-Ongoing (2026)

Conservation activities

Challenges

Table 5. Challenges reported for Oba Hills Forest Reserve

Challenges	Specific challenges	Source	Year(s)
1 Site management	1.3 Corruption	Greengrass 2006
2 Resources and capacity	2.3 General lack of funding	Greengrass 2006
4 Institutional support	4.1 Lack of law enforcement	Greengrass 2006

Challenges

Enablers

Table 6. Enablers reported for Oba Hills 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 Oba Hills 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. subm. 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 (see Kiribou et al. subm. for details).

Table 8. Estimated past and projected climatological characteristics in Oba Hills 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]	26.6	27.7	27.6	27.9	29
Annual precipitation [mm]	1408	1431	1452	1416	1487
Max no. consecutive dry days (per year)	43.2	43.8	43.6	44.3	47.4
No. days with heavy precipitation (per year)	5.4	9.8	10.1	9.6	11

Table 9. Projected exposure of apes to extreme climate impact events in Oba Hills 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	4.5	4.47	3	2.84	4.5	4.96	9.5	5.52
Drought	0	0	0	0	0	0	0	0
Heatwave	2	100	4.5	100	2	100	8.5	100
River flood	0	0	1	2.18	0	0	1	1.67
Tropical cyclone	0	0	0	0	0	0	0	0
Wildfire	30	0.55	30	0.53	29	0.53	29	0.7

• 

  Precipitation anomaly in Oba Hills Forest Reserve

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  Temperature anomaly in Oba Hills Forest Reserve

References

Greengrass, E.J. (2006). A survey of chimpanzees in south-west Nigeria. Report to the NCF-WCS Biodiversity Research Programme.

Greengrass, E.J. (2009). Chimpanzees are close to extinction in Southwest Nigeria. Primate Conservation 24(1), 77-83. doi: 10.1896/052.024.0105

Kormos, R., Boesch, C., Bakarr, M.I., Butynaki, T.M. (2003) West African Chimpanzees: Status survey and conservation action plan. Gland, Switzerland: IUCN.

Wahab, M.K.A. (2016). Wildlife Environmental Conservation: A Case Study of Oba Hill Forest Reserve. J Ecosys Ecograph, 6(214). doi: 10.4172/2157-7625.1000214

Page created by: APES Atlas Team Date: 2020-11-15