Pan troglodytes ssp. schweinfurthii 

Scope: Global
Language: English

Translate page into:

Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Primates Hominidae

Scientific Name: Pan troglodytes ssp. schweinfurthii (Giglioli, 1872)
Parent Species:
Common Name(s):
English Eastern Chimpanzee
Taxonomic Source(s): Mittermeier, R.A., Rylands, A.B. and Wilson D.E. 2013. Handbook of the Mammals of the World: Volume 3 Primates. Lynx Edicions, Barcelona.
Taxonomic Notes:

The four commonly recognised subspecies of Chimpanzee are: the Western Chimpanzee (Pan troglodytes verus); the Nigeria-Cameroon Chimpanzee (P. t. ellioti); the Central Chimpanzee (P. t. troglodytes); and the Eastern Chimpanzee (P. t. schweinfurthii). The relative importance of different threats faced by each taxon varies across Africa, making a regional approach valuable for conservation purposes. We, therefore, use a four-subspecies classification system here, acknowledging that future work may lead to recognition of more or fewer subspecies.

Assessment Information [top]

Red List Category & Criteria: Endangered A4bcd ver 3.1
Year Published: 2016
Date Assessed: 2016-03-18
Assessor(s): Plumptre, A., Hart, J.A., Hicks, T.C., Nixon, S., Piel, A.K. & Pintea, L.
Reviewer(s): Williamson, E.A. & Mittermeier, R.A.
Contributor(s): Balmforth, Z., Butynski, T.M., Cox, D., Critchlow, R., Davenport, T., Hall, J.S., Hunt, K., Kamenya, S., Kirkby, A., Kujirakwinja, D., Mitani, J., Moore, J., Nakamura, M., Nishuli, R., Reynolds, V., Vieilledent, G. & Wilson, M.

Pan troglodytes schweinfurthii is estimated to have experienced a significant population reduction in the past 20–30 years, especially in the Democratic Republic of Congo (DRC). The Albertine Rift escarpment in DRC is a stronghold for this subspecies (Plumptre et al. 2010a), but recent surveys indicate 80–98% declines at key sites in just 20 years, principally caused by illegal hunting for bushmeat (Plumptre et al. 2015). While habitat destruction presents a relatively low threat to the large population inhabiting lowland forests to the west of the Rift, extensive land conversion in the eastern highlands has destroyed much of the sub-montane forest where Chimpanzees in this region tend to occur at higher densities. Expanding human populations are fragmenting both the forests and the Chimpanzee populations that still exist in these highlands. Populations in northern DRC are relatively stable (Hicks et al. 2014); however, recent intrusions by artisanal miners and the bushmeat trade are resulting in significant numbers of Chimpanzees being killed (Hicks et al. 2010). In Tanzania and Uganda, Chimpanzee decline results mainly from habitat loss outside protected areas.

Although some Eastern Chimpanzee populations appear to be stable, particularly in well-managed protected areas east of the Albertine Rift (Wanyama et al. 2009, Plumptre et al. 2010b, Piel et al. 2015, Sop et al. 2015), human population growth, road construction, and conversion of habitat for agriculture will increasingly adversely affect Chimpanzees. Therefore, the population reduction over three generations (with one generation estimated to be 25 years) from 1980 to 2055 is expected to exceed 50%, hence qualifying this taxon as Endangered under criterion A. The prediction of continued decline of Eastern Chimpanzee populations is a precautionary approach based on the rapidly-increasing human population in East Africa and the degree of political instability in some range countries.

Previously published Red List assessments:

Geographic Range [top]

Range Description:

P. t. schweinfurthii ranges from the Ubangi River/Congo River in southeast Central African Republic (CAR) and Democratic Republic of Congo (DRC), to Burundi, Rwanda, western Uganda and western Tanzania. Few survey data are available for Central African Republic; it is known that chimpanzees have been extirpated from the Bangassou forest (Williamson et al. 2004), but are persisting in Chinko Nature Reserve (T. Aebischer pers. comm. 2015). Camera-trap images have provided recent confirmation that chimpanzees still occur in Garamba National Park, in DRC (African Parks 2012) and in South Sudan (Mongabay 2015).

Countries occurrence:
Burundi; Central African Republic; Congo, The Democratic Republic of the; Rwanda; South Sudan; Tanzania, United Republic of; Uganda
Additional data:
Lower elevation limit (metres):300
Upper elevation limit (metres):2790
Range Map:Click here to open the map viewer and explore range.

Population [top]


The vast majority of P. t. schweinfurthii are found in DRC (173,000–248,000, Plumptre et al. 2010a), including a large population that occupies areas previously considered to be outside this subspecies' geographic range (Hicks et al. 2014). It is estimated that 37,000 Chimpanzees remain the Maiko-Tayna-Kahuzi-Biega landscape, from the Kabobo Massif in the south, through Kahuzi-Biega National Park up to Maiko National Park and the Usala/Tayna Forest region (Plumptre et al. 2015). The Ituri forest in northeastern DRC forest likely supports 12,000 Chimpanzees, with two thirds of them in the protected Okapi Faunal Reserve (Vosper et al. 2013, Maisels pers. comm. 2016). In Virunga National Park, an estimated 1,376 Chimpanzees live in the lowland forest area and Rwenzori flanks together with a forest corridor linking Virunga Park to Mt. Hoyo Reserve (Plumptre et al. 2008). This population is contiguous with Semliki National Park and Rwenzori National Park in Uganda.

Approximately 8,000 Eastern Chimpanzees occur outside DRC: roughly 5,000 are in western Uganda (Plumptre et al. 2003a). Data from the protected areas (Budongo and Bugoma forest reserves, Kibale National Park) show that the populations there are relatively stable (Wanyama et al. 2009, Plumptre et al. 2010b); however, forest is being lost at many smaller sites. Most Chimpanzees in Rwanda live in Nyungwe National Park, where their numbers are relatively stable at around 400 individuals (WCS Rwanda unpubl. data). This population is contiguous with a somewhat smaller population in Kibira National Park in Burundi (Hakizimana and Huynen 2013). The size of the populations in CAR and South Sudan is unknown.

Fewer than 2,500 chimpanzees now remain in Tanzania (A. Piel and F. Stewart, pers. comm.) and almost all of them reside in the Greater Mahale Ecosystem (GME). Longitudinal survey work in western Tanzania has produced mixed results: in the Masito-Ugalla areas of northern GME, areas first surveyed in 2007 exhibited similar density estimates in 2014 (Piel et al. 2015); in the southern GME, critical areas such as Ntakata and Kalobwe forests, which serve as important genetic reservoirs for Mahale, were also stable between 2011 and 2015; whilst Wansisi Hills, potentially the most eastern population of P. t. schweinfurthii, was found to be under heavy threat with Chimpanzee numbers and habitat dwindling in just two years, between 2012 and 2014 (Piel and Stewart, unpubl. data).

Great ape population estimates are made using a standard index of abundance: night nest abundance and distribution, sometimes combined with predictive modelling.

Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:Yes
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:

Eastern Chimpanzees are found predominantly in lowland and submontane tropical forests, and forest galleries extending into savanna woodlands. They occur at relatively high densities at 1,000-2,000 m asl. Montane forest at higher altitudes is not good chimpanzee habitat. They are omnivorous, and their diet varies between populations and seasons. Ripe fruit constitutes about half the diet; leaves, bark and stems are also important. Mammals are a small but significant component of the diet of many populations. Eastern chimpanzees form communities of 20–150 individuals (Mitani and Watts 2005). Home ranges are larger in woodland forest mosaics than in mixed forest (6 km² at Budongo in Uganda, Newton-Fisher 2003; 72 km² at Semliki in Uganda, Samson and Hunt 2012).

Generation Length (years):25
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade:

Chimpanzees are completely protected by national and international laws in all countries of their range, and it is, therefore, illegal to kill, capture or trade in live Chimpanzees or their body parts.

Threats [top]

Major Threat(s):

The major threats to Eastern Chimpanzees are:

1. Poaching

Despite the fact that all killing, capture or consumption of great apes is illegal, poaching represents the greatest threat to great apes in eastern DRC. Due to low Chimpanzee population densities and slow reproductive rates, hunting often leads to the local extirpation of Chimpanzee populations.

a) Bushmeat: Eastern Chimpanzees are killed illegally for bushmeat, particularly in DRC, which leads to reductions in numbers or extirpation. Poaching is intense around artisanal mining and logging camps, where bushmeat is usually the main source of protein available. Great apes are generally hunted opportunistically, but are sometimes targeted because they provide more meat than smaller mammals, such as duikers.

(b) Live trade: significant numbers of Chimpanzees are killed for bushmeat and their infants may then be trafficked as pets (Hicks et al. 2010). Although all trade in Chimpanzees and their body parts is illegal, a small clandestine trade persists is some parts of Africa. The hundreds of Chimpanzees housed in sanctuaries in the Eastern Chimpanzee range states and continuing confiscations are strong indications of hunting pressures.

(c) Human-wildlife conflict: people kill Chimpanzees intentionally to protect their crops (Hockings and Humle 2009).

(d) Snares: Chimpanzees may also be maimed or killed unintentionally when caught in snares set for other animals, such as duikers (e.g., Quiatt et al. 2002).

2. Habitat destruction and degradation

(a) Smallerholder and shifting agriculture: rapid growth in human populations across Africa is expected to lead to continued widespread conversion of forest and woodland to agricultural land.

(b) Industrial agriculture: oil-palm plantations could become a threat in the future as eastern DRC stabilises.

3. Disease

The main cause of death in Chimpanzees at Gombe and Mahale in Tanzania is infectious disease (e.g., Goodall 1986, Nishida et al. 2003). Because Chimpanzees and humans are so similar, Chimpanzees succumb to many diseases that afflict humans. The frequency of encounters between Chimpanzees and humans and/or human waste is increasing as human populations expand, leading to higher risks of disease transmission between humans and Chimpanzees. If not properly managed, research and tourism also create opportunities for disease transmission between humans and Chimpanzees (Gilardi et al. 2015).

4. Mining

Artisanal mining is a major source of threat to Chimpanzees, particularly in DRC, from Ituri in the northeast to Kabobo in the south. Artisanal mining lures workers into previously remote and isolated forests to dig for gold, coltan, tin and wolframite. Once at these remote sites, people rely on bushmeat as a primary source of protein. In addition to intense poaching pressure, mining puts Chimpanzees at increased risk of contracting diseases carried by people living in unsanitary camps. Because of the potential wealth of mines, many are controlled by armed militias, who provide access to firearms, which not only makes hunting of wildlife easier, but monitoring/protection efforts become dangerous activities. Large-scale industrial mining currently represents a low risk to Eastern Chimpanzees; however, sites are being established west of Itombwe and the potential for large-scale iron-ore extraction is being explored by mining corporations in the Ituri region. Oil exploitation along the Albertine Rift in eastern DRC and western Uganda is planned as the Great Lakes Region becomes more stable. Major industrial developments will trigger immigration, which brings with it a host of associated threats to Chimpanzees and their habitats. 

5. Climate change

Climate change is unlikely to be a major threat to Chimpanzees in eastern DRC and western Uganda, as they occur in a variety of habitat types across a wide range of altitudes and are very adaptable. Some regions where it is predicted that rainfall will decline with global warming, such as western Tanzania, may lose Chimpanzees if conditions become much drier (the region is already one of the driest habitats where this subspecies occurs). However, there has been little research into how the species will respond to climate change. Niche modelling predicts a contraction of the Eastern Chimpanzee's range with increasing temperature (A.J. Plumptre unpublished data), but this assumes that Chimpanzees will not adapt to change, which may not be the case, given that other Chimpanzee subspecies occur outside these niche envelopes.

Conservation Actions [top]

Conservation Actions:

Pan troglodytes is listed on Appendix I of CITES and as Class A of the African Convention. Eastern Chimpanzees are protected by laws in their range countries and are present in numerous national parks throughout their range, although many occur outside protected areas. Stricter enforcement of wildlife laws and more effective management of protected areas are urgently needed. Conservation education and promotion of economic alternatives to hunting and land-extensive agriculture should also be supported.

IUCN has published a regional conservation action plan for eastern chimpanzees, which is effective until 2020 (Plumptre et al. 2010a). National action plans for eastern chimpanzee conservation have also been developed for DRC (Maldonado et al. 2012), Tanzania (TANAPA et al. 2015) and Uganda (Plumptre et al. 2003b). These documents are available for download at:

Errata [top]

Errata reason: This is an errata version of the 2016 assessment to correct some minor grammatical errors in the Population and Habitats & Ecology sections.

Citation: Plumptre, A., Hart, J.A., Hicks, T.C., Nixon, S., Piel, A.K. & Pintea, L. 2016. Pan troglodytes ssp. schweinfurthii (errata version published in 2016). The IUCN Red List of Threatened Species 2016: e.T15937A102329417. . Downloaded on 22 September 2018.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided