Greater Mahale Ecosystem

East Africa > Tanzania > Greater Mahale Ecosystem

Summary

• Eastern chimpanzees (Pan troglodytes schweinfurthii) are present in the Greater Mahale Ecosystem.
• It has been estimated that 2,600 individuals occur in the site.
• The chimpanzee population trend is decreasing.
• The site has a total size of 20,000 km².
• Key threats to chimpanzees include human settlements in important habitat, logging and charcoal production, fires, expansion of agriculture and herding, and poaching.
• Conservation activities have focused on anti-poaching patrols and presence of researchers, and providing fuel-efficient ovens.
• The site holds approximately 90% of the chimpanzee population in Tanzania.

Site characteristics

Located in western Tanzania, the Greater Mahale Ecosystem includes the Mahale Mountains National Park and its surrounding natural habitat. In addition to the eastern chimpanzee, other species of conservation concern that occur in the area include red colobus monkeys, elephants, lions, sables, and the endemic bird Kungwe apalis (WCS). A total of 1,939 mammal, bird, reptile, amphibian and plant species have been recorded at the site, of which 15 species are endemic to the Albertine Rift and 28 species are threatened (CR, EN, VU) under the IUCN Red List (WCS).

Table 1. Basic site information for Greater Mahale Ecosystem

Area	20,000 km²
Coordinates
Designation	Unclassified
Habitat types	Subtropical/tropical montane forest, subtropical/tropical high altitude grassland

IUCN habitat categories Site designations

Ape status

The WCS Albertine Rift Program conducted surveys of the Greater Mahale Ecosystem in the mid 2000s with Jane Goodall Institute (JGI), to estimate chimpanzee numbers for the area and assess other biodiversity WCS).

Table 2. Ape population estimates in Greater Mahale Ecosystem

Species	Year	Abundance estimate (95% CI)	Density estimate [ind./ km²] (95% CI)	Encounter rate (nests/km)	Area	Method	Source	Comments	A.P.E.S. database ID
Pan troglodytes schweinfurthii	2005	2,600			Greater Mahale Ecosystem	Extrapolation of suitable habitat based on satellite imagery and densities for different areas	Plumptre et al. 2010

Threats

In Tanzania, 90% of the country’s chimpanzees are found in the Greater Mahale Ecosystem, where suitable habitat is being lost and fragmented by the expansion of human settlements, conversion of land for agriculture, logging, and cattle herding (Chitayat et al. 2021). Chimpanzees in savanna-woodland mosaics, such as in the Greater Mahale Ecosystem, already live at relatively low densities, highlighting the need to identify and protect areas critical for chimpanzee conservation (Chitayat et al. 2021).

Table 3. Threats to apes in Greater Mahale Ecosystem

Category	Specific threats	Threat level	Quantified severity	Description	Year of threat
1. Residential & commercial development	1.1 Housing & urban areas	Present, but threat severity unknown		People settling in the area tend to locate near water sources. As a result, small riverine strips of forest, critical for chimpanzees and the endemic Kungwe apalis, are disappearing (WCS n.d.)	Ongoing (2021)
2. Agriculture & aquaculture	2.1 Annual & perennial non-timber crops	High		Conversion of chimpanzee habitat into agricultural land (GMERC n.d.).	Ongoing (2021)
	2.3 Livestock farming & ranching	High		Cattle herding (Chitayat et al. 2021).	Ongoing (2021)
3. Energy production & mining		Unknown
4. Transportation & service corridors		Unknown
5. Biological resource use	5.1 Hunting & collecting terrestrial animals	Present, but threat severity unknown		Injuries caused by snares (GMERC).	Ongoing (2021)
	5.3 Logging & wood harvesting	High		Clearing the forest for charcoal production (GMERC).	Ongoing (2021)
6. Human intrusion & disturbance	6.2 War, civil unrest & military exercises			Settlement of refugees from the wars in Burundi and Democratic Republic of Congo in the landscape has led to loss of habitat (WCS n.d.).	Unknown
7. Natural system modifications	7.1 Fire & fire suppression	High		Fires ignited by humans, contributing to habitat loss (WCS n.d., GMERC n.d.).	Ongoing (2021)
8. Invasive & other problematic species, genes, diseases		Unknown
9. Pollution		Unknown
10. Geological Events		Absent
11. Climate change & severe weather		Unknown
12. Other options		Absent

IUCN Threats list

Conservation activities

Government-led patrols are conducted in partnership with the Jane Goodall Institute to fight illegal activities, such as poaching and herding (GMERC n.d.).

Table 4. Conservation activities in Greater Mahale Ecosystem

Category	Specific activity	Description	Year of activity
1. Residential & commercial development	Not reported
2. Agriculture & aquaculture	Not reported
3. Energy production & mining	Not reported
4. Transportation & service corridors	Not reported
5. Biological resource use	5.6. Conduct regular anti-poaching patrols	GMERC organise and sponsor patrols to combat illegal activities since 2009.	Ongoing (2021)
6. Human intrusion & disturbance	Not reported
7. Natural system modifications	Not reported
8. Invasive & other problematic species, genes, diseases	Not reported
9. Pollution	Not reported
10. Education & Awareness	Not reported
11. Habitat Protection	Not reported
12. Species Management	Not reported
13. Livelihood; Economic & Other Incentives	13.2. Provide non-monetary benefits to local communities for sustainably managing their forest and its wildlife (e.g. better education, infrastructure development)	Providing fuel efficient ovens GMERC.	Ongoing (2021)
	13.3. Run research project and ensure permanent human presence at site	Research is regularly conducted at the site GMERC.	Ongoing (2021)

Conservation activities list (Junker et al. 2017)

Challenges

Table 5. Challenges reported for Greater Mahale Ecosystem

Challenge	Source
Not reported

Research activities

The Greater Mahale Ecosystem Research and Conservation group cover several topics in their research, such as chimpanzee behavioral ecology, bioacoustics, environmental and biodiversity monitoring, as well as research on yellow baboons and red-tailed monkeys (GMERC n.d.).

Documented behaviours

Table 6. Ape behaviors reported for Greater Mahale Ecosystem

Behavior	Source
Not reported

External links

Greater Mahale Ecosystem Research and Conservation
Greater Mahale Ecosystem WCS
Greater Mahale Ecosystem Frankfurt Zoological Society

Relevant datasets

A.P.E.S Portal

References

Chitayat AB, Wich SA, Lewis M, Stewart FA, Piel AK (2021) Ecological correlates of chimpanzee (Pan troglodytes schweinfurthii) density in Mahale Mountains National Park, Tanzania. PLoS ONE 16(2): e0246628. https://doi.org/10.1371/journal.pone.0246628
GMERC (n.d.). Conservation. https://www.gmerc.org/conservation
WCS. (n.d.). Greater Mahale Ecosystem. https://albertinerift.wcs.org/Wild-Places/Greater-Mahale-Ecosystem.aspx
Plumptre AJ, Rose R, Nangendo G, Williamson E a., Didier K, Hart J, et al. Eastern Chimpanzee (Pan troglodytes schweinfurthii) Status Survey and Conservation Action Plan 2010–2020. Gland, Switzerland; 2010.

Page completed by: A.P.E.S. Wiki team Date: 14/10/2021