Monte Alén National Park

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Summary

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• Central chimpanzees (Pan troglodytes troglodytes) & western lowland gorillas (Gorilla gorilla gorilla) are present in Monte Alén National Park.
• The population sizes are unknown.
• The great ape population trend is unknown.
• The site has a total size of 2,000 km².
• Key threats to great apes are hunting, logging, and pressure for farmland.
• Conservation activities include awareness raising activities and biomonitoring.

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  © R. Nchama Okenve

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  © R. Nchama Okenve

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  © R. Nchama Okenve

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  © R. Nchama Okenve

Site characteristics

Established in 1990, Monte Alén National Park is located in Equatorial Guinea. Monte Alén and Monte Mitra (both located within the National Park) are considered the highest massifs on mainland Equatorial Guinea, although available elevation data remain incomplete. The park is bounded to the west by the large, fast-flowing Uoro River, and to the east by the main road linking Niefang to Gabon. The size of the park was doubled in 1998 with the inclusion of Mount Mitra, and in 2000 another section to the south was added (Key Biodiversity Areas Partnership 2025). The site is designated as an Important Bird Area and also a Key Biodiversity Area (BirdLife International 2020, Key Biodiversity Areas Partnership 2025). Primate species include Colobus satanas (VU, fairly common), Cercocebus torquatus (LR/near threatened), Mandrillus sphinx (LR/nt), Gorilla gorilla (EN), and Pan troglodytes (EN) (Key Biodiversity Areas Partnership 2025).

Table 1. Basic site information for Monte Alén National Park

Species	Pan troglodytes troglodytes, Gorilla gorilla gorilla
Area	2,000 km²
Coordinates	Lat: 1.533574 , Lon: 10.126031
Type of site	Protected area (National Park)
Habitat types	Subtropical/tropical moist lowland forest, Subtropical/tropical moist montane forest
Type of governance	Governance by government

Types of sites Governance types Habitat types

Ape status

The site has been identified as a priority area for gorillas and chimpanzees in Equatorial Guinea, as it holds very high ape and large mammal densities (Murai et al. 2013).

Table 2. Ape population estimates reported for Monte Alén National Park

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
Gorilla gorilla gorilla	1994		2.16			Monte Alén National Park	Line transects		Garcia & Mba 1997	145 gorilla nests were reported. Survey effort: 84.9 km. Nest encounter rate is the mean taken from three estimates (dense forest (1.01), open forest (0.32), secondary forest (5.15)).
Pan troglodytes troglodytes	1994		3.02			Monte Alén National Park	Line transects		Garcia & Mba 1997	290 chimpanzee nests recorded. Survey effort: 84.9 km. Nest encounter rate is the mean taken from three estimates (dense forest (3.41), open forest (5.35), secondary forest (0.31)).
Pan troglodytes troglodytes & Gorilla gorilla gorilla	2024	Present				Monte Alén National Park	Line transects, Camera trap		Nchama Okenve, R., pers. comm. 2025

Sampling methods Analytical frameworks

Threats

Table 3. Threats to apes reported for Monte Alén National Park

Category	Specific threats	Threat level	Description	Year of threat
5 Biological resource use	5.1 Hunting & collecting terrestrial animals	High (more than 70% of population affected)	Commercial trapping and hunting (BirdLife International 2020, Nchama Okenve, R., pers. comm. 2025). Bristol Zoological Society conducts biomonitoring in the site and have repeatedly reported hunting signs, including snares, shotgun shells, and presence of hunting dogs (McLaughlin, McCabe & Fernández 2020).	2005-Ongoing (2020)
5 Biological resource use	5.1.5 Persecution/human wildlife conflict	Present (unknown severity)	Human-wildlife conflict due to crop raiding (Nchama Okenve, R., pers. comm. 2025).	Ongoing (2025)
2 Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	Present (unknown severity)	Agricultural expansion (Sunderland 2005, Kenfack 2014). Farming is mainly occurring at the borders of the park (Nchama Okenve, R., pers. comm. 2025).	2005-Ongoing (2025)
5 Biological resource use	5.3.1 Subsistence logging	Present (unknown severity)	Logging activity (Sunderland 2005, Kenfack 2014), mainly subsistence logging or wood harvesting (Nchama Okenve, R., pers. comm. 2025).	2005-Ongoing (2025)

Threats

Conservation activities

The park was managed by the European-Union-funded ECOFAC project from 1992 until 2005 (Key Biodiversity Areas Partnership 2025, Nchama Okenve, R., pers. comm. 2025). Bristol Zoological Society is conducting biomonitoring activities in the site and, with support from IUCN, there are projects to reduce human-wildlife conflict around the park as well as support for micro-projects to generate income (Nchama Okenve, R., pers. comm. 2025).

Table 4. Conservation activities reported for Monte Alén National Park

Category	Specific activity	Description	Implementing organization(s)	Year of activity
5 Protection & restoration	5.2 Legally protect ape habitat	The site is a National Park.		1990-Ongoing (2025)
2 Counter-wildlife crime	2.11 Implement monitoring surveillance strategies (e.g., SMART) or use monitoring data to improve effectiveness of patrols	Monitoring program that uses different methods (recces, line transects, camera traps) also detects human activities, such as illegal hunting (McLaughlin, McCabe & Fernández 2020).	Bristol Zoological Society, INDEFOR	2019-Ongoing (2020)
2 Counter-wildlife crime	Other	Eco-guards patrol and take care of the park (Nchama Okenve, R., pers. comm. 2025).	IUCN	Ongoing (2025)
4 Education & awareness	4.4 Regularly play TV and radio announcements to raise ape conservation awareness	Radio programs to raise awareness in local population (Nchama Okenve, R., pers. comm. 2025).	INDEFOR	Ongoing (2025)
7 Economic & other incentives	7.1 Provide monetary benefits to local communities for sustainably managing their forest and its wildlife (e.g., REDD, alternative income, employment)	Funding of microprojects to support income generation in local communities (Nchama Okenve, R., pers. comm. 2025).	IUCN, Bristol Zoological Society	Ongoing (2025)
7 Economic & other incentives	Other	There is some eco-tourism in the site, but not with permanent presence (Nchama Okenve, R., pers. comm. 2025).		Ongoing (2025)

Conservation activities

Challenges

Table 5. Challenges reported for Monte Alén National Park

Challenges	Specific challenges	Source	Year(s)
2 Resources and capacity	2.3 General lack of funding	Kenfack 2014, Nchama Okenve, R., pers. comm. 2025	2014-Ongoing (2025)
2 Resources and capacity	2.1 Lack of capacity/training	Kenfack 2014	Ongoing (2014)
2 Resources and capacity	2.4 Lack of continuous/long-term funding	Nchama Okenve, R., pers. comm. 2025	Ongoing (2025)
4 Institutional support	4.1 Lack of law enforcement	McLaughlin, McCabe & Fernández 2020, Nchama Okenve, R., pers. comm. 2025	2020-Ongoing (2025)

Challenges

Enablers

Table 6. Enablers reported for Monte Alén National Park

Enablers	Specific enablers	Source	Year(s)
1 Site management
2 Resources and capacity	2.6 External partnerships that add expertise or resources	McLaughlin, McCabe & Fernández 2020	Ongoing (2020)
3 Engaged community
4 Institutional support
5 Ecological context
6 Safety and stability

Enablers

Documented behaviours

Table 7. Behaviours documented for Monte Alén National Park

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 Monte Alén National Park

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]	24.1	25.2	25.1	25.3	26.4
Annual precipitation [mm]	3229	3314	3289	3382	3341
Max no. consecutive dry days (per year)	17.9	7.6	6.7	7.2	6.7
No. days with heavy precipitation (per year)	6.4	11.3	10.6	11.3	12.6

Table 9. Projected exposure of apes to extreme climate impact events in Monte Alén National Park

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	1.5	0	1	0	1.5	0	6	0
Drought	0	0	0	0	0	0	0	0
Heatwave	0	0	0	0	1	50	2.5	50
River flood	1.25	1.15	1	1.33	1	1.26	3	1.54
Tropical cyclone	0	0	0	0	0	0	0	0
Wildfire	26.5	0.12	25.25	0.1	25.75	0.12	26.5	0.12

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  Precipitation anomaly in Monte Alén National Park

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  Temperature anomaly in Monte Alén National Park

References

BirdLife International. (2020). Important Bird Areas factsheet: Monte Alen National Park. Downloaded from http://www.birdlife.org on 10/12/2020.
Garcia, J. E., & Mba, J. (1997). Distribution, status and conservation of primates in Monte Alen National Park, equatorial Guinea. Oryx, 31(1), 67-76.
Kenfack, C.E. (2014). El paisaje del Monte Alén /Montes de Cristal. CIFOR report, retrieved from: https://www.cifor.org/publications/pdf_files/brief/4507-brief.pdf
Key Biodiversity Areas Partnership (2025) Key Biodiversity Areas factsheet: Monte Alen National Park. Extracted from the World Database of Key Biodiversity Areas. Developed by the Key Biodiversity Areas Partnership: BirdLife International, IUCN, American Bird Conservancy, Amphibian Survival Alliance, Conservation International, Critical Ecosystem Partnership Fund, Global Environment Facility, Re:wild, NatureServe, Rainforest Trust, Royal Society for the Protection of Birds, World Wildlife Fund and Wildlife Conservation Society. Downloaded from https://keybiodiversityareas.org/ on Nov 14, 2025.
McLaughlin, P., McCabe, G., & Fernández, D. (2020, June). A long-term monitoring programme for great apes in Monte Alén National Park. Gorilla Journal, (60), 20–22. Retrieved from https://www.berggorilla.org/en/gorillas/species/western-gorillas/articles-western-gorillas/a-long-term-monitoring-programme-for-great-apes-in-monte-alen-national-park/
Miles, J. O. C. L., & Annan, K. (2005). World atlas of great apes and their conservation. Univ of California Press.
Murai M, Ruffler H, Berlemont A, Campbell G, Esono F, Agbor A, et al. (2013). Priority Areas for Large Mammal Conservation in Equatorial Guinea. PLoS ONE 8(9): e75024. https://doi.org/10.1371/journal.pone.0075024
Sunderland, T. C. H. (2005). A biodiversity assessment of the Monte Mitra forest, Monte Alén National Park, Equatorial Guinea. Washington, D. C.: Smithsonian Institution Press.

Page created by: Regina Nchama Okenve & APES Atlas Team Date: 2020-12-29