Oba Hills Forest Reserve
West Africa > Nigeria > Oba Hills Forest Reserve
Français | Português | Español | Bahasa Indonesia | Melayu
Summary
- 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) |
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) |
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 |
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 |
Research activities
Documented behaviours
Table 7. Behaviours documented for Oba Hills Forest Reserve
| Category | Behavior | Observation type | Prevalence | Observation dates | Source | Habituation | Species | Comment |
|---|---|---|---|---|---|---|---|---|
| Not reported |
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 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 -
Temperature anomaly in Oba Hills Forest Reserve
External links
References
Greengrass, E.J. (2006). A survey of chimpanzees in south-west Nigeria. Report to the NCF-WCS Biodiversity Research Programme. link
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. link
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
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: 2020-11-15