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Pan troglodytes ssp. troglodytes 

Scope: Global
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Primates Hominidae

Scientific Name: Pan troglodytes ssp. troglodytes
Species Authority: (Blumenbach, 1799)
Parent Species:
Common Name(s):
English Central 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. Recent mitochondrial DNA work (Gonder et al. 2011) suggests that there are three major clades of Chimpanzees: Pan troglodytes verus in West Africa, P. t. ellioti between the Dahomey Gap and the Sanaga River in Cameroon, and P. t. troglodytes in Central and East Africa, the last of which is usually subdivided into P. t. schweinfurthii and P. t. troglodytes (e.g., Fünfstück et al. 2015). 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, acknowledging that future work may lead to recognition of more or fewer subspecies.

Assessment Information [top]

Red List Category & Criteria: Endangered A4bcde ver 3.1
Year Published: 2016
Date Assessed: 2016-01-29
Assessor(s): Maisels, F., Strindberg, S., Greer, D., Jeffery, K., Morgan, D.L. & Sanz, C.
Reviewer(s): Williamson, E.A. & Mittermeier, R.A.
Contributor(s): Baillie, J., Butynski, T.M., Dupain, J., Gatti, S., Tutin, C. & Walsh, P.D.
Justification:

Pan troglodytes troglodytes has a very large geographic range (over 700,000 km2) and a relatively large population size, currently estimated at about 140,000 individuals (Strindberg et al. in prep). However, this subspecies has experienced a significant population reduction since the 1970s. Between 1983 and 2000, the country of Gabon lost half its great ape population to poaching and disease, at an annual rate of decline 4% (calculated from Walsh et al. 2003). A more recent study examined nest survey data collected between 2003 and 2013 across the entire range of the taxon and created a predictive model to map Central Chimpanzee density and distribution (Strindberg et al. in prep). Although the results show no statistically significant decline during those 10 years, Central Chimpanzee populations remain highly vulnerable to poaching and disease. Due to their slow life history and a generation time estimated to be 25 years, Chimpanzee populations cannot sustain high mortality levels, whether disease-induced or caused by humans. Given the scale of the poaching problem across Central Africa, this taxon is likely to be experiencing declines significant in terms of the population status, which we do not have the statistical power to detect.

It is suspected that this reduction will continue for the next 30 to 40 years due to illegal hunting and expansion of the commercial bushmeat trade, and to habitat loss and degradation occurring at an increasing rate as a result of expanding human activities. The causes of the reduction, although largely understood, have certainly not ceased and are not easily reversible. The predicted continuation of the population decline is a precautionary approach based on the rapidly-increasing human population density in the region, and the expansion of land clearing for industrial-scale agricultural plantations, which requires the clearcutting of forest and is likely to accelerate in the next two to three decades. The effects of climate change will also become increasingly evident. At the same time, the threat of emerging infectious diseases is ongoing; there is, for example, evidence that Ebolavirus will continue to spread (Walsh et al. 2005), which would have devastating consequences for Central African great ape populations. At a conservative rate of loss of 1% each year, the population reduction over three generations (75 years) from 1975–2050 is likely to exceed 50%, hence qualifying Central Chimpanzees as Endangered under criterion A.

Previously published Red List assessments:

Geographic Range [top]

Range Description:

Pan troglodytes troglodytes (Blumenbach 1799) has a very large geographic range (just over 700,000 km²). The eastern limit of their distribution is the Ubangi River; the northwestern limit is the Sanaga River in Cameroon; the northern limit is the forest-savanna boundary to a maximum of roughly 6oN. The Congo River south of its confluence with the Ubangi, to the coast, then becomes the southern and southeastern limit. Distribution is closely related to the proportion of forest cover in each country in their range: most Central Chimpanzees are found in the Republic of Congo (42%), followed by Gabon (~34%) and southwestern Cameroon (17%) (Strindberg et al. in prep).

Countries occurrence:
Native:
Angola (Angola, Cabinda); Cameroon; Central African Republic; Congo; Congo, The Democratic Republic of the; Equatorial Guinea (Equatorial Guinea (mainland)); Gabon
Additional data:
Continuing decline in extent of occurrence (EOO):Yes
Upper elevation limit (metres):750
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:

Central Chimpanzees occur throughout almost all the protected areas and logging concessions in their geographic range, in both terra firma and swamp forests; the majority (81%) live outside the protected area network (Strindberg et al. in prep). Great ape population estimates are made using a standard index of abundance: night nest abundance and distribution, sometimes combined with predictive modelling. A recent meta-analysis examined 83 nest survey datasets collected using standardised methods across the entire range of Central Chimpanzees and western lowland gorillas between 2003 and 2013. Half the surveys were carried out in protected areas, the other half in logging concessions or unattributed forests, and a predictive model was produced to map great ape density and distribution. Excluding DRC where only a small number of Central Chimpanzees remain, the population is now estimated to be ~140,000 (Strindberg et al. in prep.), updating the previous estimate of 70,000–117,000 individuals (Oates et al. 2008). The results of the analysis show that no statistically-significant overall decline occurred in the decade between 2003 and 2013 (Strindberg et al. in prep.). However, there may be a time lag associated with these impacts on younger cohorts of individuals or on the overall reproductive fitness of these apes that is not detected with current survey methods. Thus, Central Chimpanzees are likely to be experiencing significant population declines that we do not have the statistical power to detect.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:140000Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:

Central Chimpanzees are found predominantly in moist lowland tropical forests and swamp forests. Although they prefer mixed species forest, they will use other forest types for nesting and foraging, including monodominant forest stands comprised largely of medium- to large-sized Gilbertiodendron trees. Chimpanzees are omnivorous, and their diets vary greatly between populations and seasons. Ripe fruit is the major constituent of their diet; young leaves, bark, stems and flowers are also important (Morgan and Sanz 2006, Head et al. 2011). Faunivory has been documented in all groups studied and mammals comprise a small but significant component of their diet. Consumption of other primates has been documented, but appears to be less frequent in Central Chimpanzees than in conspecifics inhabiting the forests of East and West Africa. Chimpanzee community sizes of 64–71 individuals have been recorded (Morgan 2007). The size of Chimpanzee community home ranges in Goualougo, Republic of Congo, is 13.7–25.6 km² (Morgan 2007). In Loango, Gabon, minimum home range size can reach 45 km² (Arandjelovic et al. 2011).

Generation length is estimated to be 25 years (24.6 in Langergraber et al. 2012). Central Chimpanzees have an interbirth interval of 6.04±0.73 years between surviving offspring, which decreases to 3.39±0.77 years when an offspring does not survive (Morgan and Sanz, unpublished data).

Systems:Terrestrial
Generation Length (years):24.6
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 P. t. troglodytes are:

  1. Poaching. Illegal hunting for bushmeat is a serious problem across Central Africa and is the primary driver of Central Chimpanzee population declines. Until the mid-1990s, much of their range was a series of vast, roadless forest blocks, to which access was extremely difficult and where human population density was very low. In the last quarter of a century, however, almost all terra firma forest in the non-protected areas of the Central Chimpanzee’s range has been attributed as logging concessions (Global Forest Watch 2016). This means that most of the once-remote, previously inaccessible forest is now covered by a network of logging roads (Laporte et al. 2007), which provides rapid access to hunters entering the forest and to traffickers taking consignments of bushmeat out of the forest to distant destinations – often towns and cities where bushmeat fetches the highest prices. Throughout Central Africa, mining permits for prospection or extraction are being issued over an increasingly large surface area. As well as direct removal of Chimpanzee habitat (depending on the type of extraction), mining leads to very high rates of human immigration and the creation of yet more access roads, which are then used for poaching (Edwards et al. 2014, White and Fa 2014). Huge road projects are currently underway across the continent and these will substantially fragment existing Chimpanzee habitat (Laurance et al. 2015). Across their range, Central Chimpanzee densities are lowest near roads, particularly unprotected public and major logging roads (Strindberg et al. in prep), because the ease and speed of transport is now orders of magnitude higher than before the creation of the access roads, and hunting pressures are much higher. In addition, human populations in these once-remote areas have increased, as people have migrated to the new employment opportunities offered in logging towns (Wilkie et al. 2000, Poulsen et al. 2009). This is a global phenomenon, not one confined to Central Africa (Laurance et al. 2014).
  2. Disease. The second major driver of Central Chimpanzee decline is infectious disease, especially Ebola virus disease (EVD). Surveys carried out from the 1980s to the present day show that a series of massive great ape die-offs have occurred in a large, mostly-intact forested area straddling the border between northeastern Gabon and northwestern Congo, which includes several national parks and logging concessions (Walsh et al. 2003, Maisels et al. 2004, 2013). About 14% of their total area of distribution is thought to have been affected by Ebolavirus since the early 1990s. Populations in the protected areas have started to recover; however, total recovery from a disease outbreak would take a Chimpanzee population around 100 years in the absence of poaching (Walsh et al. 2003). Ebolavirus has already been detected to the east of the major river barrier (Mambili River) between Odzala-Kokoua National Park and the Sangha River and it is known that Ebolavirus can cross rivers (Reed et al. 2014), thus a future outbreak in the Ngombe concession is a strong possibility. The vast Ngombe logging concession (over 11,500 km²) and the Ntokou-Pikounda National Park (4,252 km²), which together contain about 9,500 Central Chimpanzees (Maisels et al. 2015). This area is limited to the east by the Sangha River, on the opposite side of which is the Ndoki-Likouala landscape, which contains a further 8,800 or so Central Chimpanzee (Maisels et al. 2012). To the north of the Ngombe concession is the Ngoko River, which forms the international boundary between Congo and Cameroon, and the southeastern corner of Cameroon probably contains 16,000 Central Chimpanzees in a series of national parks and logging concessions (Blake et al. 2012). As large areas can be affected by each outbreak, and rapid transmission is possible between individuals (Walsh et al. 2007, 2009), large numbers of Chimpanzees could succumb to this deadly virus within a span of weeks or months.
  3. Habitat loss and degradation. A threat that is increasingly impacting Central Chimpanzees is loss of habitat. Habitat degradation has long been ongoing, as the type of timber extraction used in Central Africa is selective logging, which removes marketable timber species, among them several important Chimpanzee foods sources (Morgan and Sanz 2007, Morgan et al. 2013). Chimpanzees are best suited to old-growth forests in this region, and even without clearcutting, the habitat change caused by selective logging is likely to impact Chimpanzee food availability and thus reduce suitability of forests for this taxon. As timber concessions undergo repeated cycles of logging, degradation over time will lead to profound changes in forest composition (Zimmerman and Kormos 2012) as the mature trees of certain species–some of high importance to Chimpanzees for food–are logged out. In the past, habitat loss (as opposed to degradation) was not an issue for most great apes in Central Africa. However, as Asian oil-palm plantations are reaching capacity, Africa has become the new frontier for this crop, and offers excellent economic prospects for countries with appropriate rainfall, soil and temperature conditions (Rival and Lavang 2014). Unfortunately, these areas coincide with good great ape habitat: 41.7% of the Pan troglodytes’ range is suitable for oil palm (Wich et al. 2014). The creation of the development corridors, which can be several kilometres wide, adds to areas of “lost forest” (Laurance et al. 2015), as does the creation of open-pit mines (Lanjouw 2014). In all central chimpanzee range states except Gabon, there is a disconnect between the various bodies responsible for land-use planning in the realms of conservation, mining and agriculture. Consequently there will be increasing competition for land between long-term conservation needs and immediate financial gain as range states explore the potential of clearing natural habitat in favour of this crop. Without careful and immediate land-use planning involving cooperation between the government bodies responsible for protected areas and wildlife on one hand, and economic agricultural development on the other, large areas of habitat could be converted to cultivated land that does not support Chimpanzees within a few decades.
  4. Climate change. Climate change is already thought to be affecting Central African tropical moist forests (Lewis et al. 2013). Although the likely impacts of global climate change in Western Equatorial Africa are not yet known, some predictions suggest a drying of this region with potentially-negative consequences for forest ecology, such as changes in forest productivity and fruit and flower phenology, increased vulnerability to fire, and even forest retreat (James et al. 2013). Seasonal changes in precipitation and temperature, and weather extremes are likely already ongoing and set to continue during the next few decades (Lovett 2015). Negative consequences for great apes in this region have already been predicted (Lehmann et al. 2010), particularly along the coast (Korstjens et al. 2010). Some species of trees that are important sources of fruit for Chimpanzees require a minimum temperature to set seed (Tutin and Fernandez 1993), so increases in temperature will prevent their fruiting. Climate change is the least likely factor for which effective action for great apes, and for African tropical forests in general, can be taken in a timely manner. Although the 2015 Conference of the Parties to the United Nations Framework Convention on Climate Change resulted in international cooperative agreement between most of the world’s nations as to the need for action, the task of reversing or even flattening current temperature trends will be extremely challenging. Nonetheless, there is potential for mitigating against the impacts of habitat degradation or conversion, which would otherwise exacerbate the effects of climate change on both the short- and long-term prospects for Chimpanzee survival.

While each of the major threats to the Central Chimpanzee's survival is described as an independent factor, these threats are often interconnected and may interact in ways that exacerbate their impacts on wildlife. For example, as access to forests is opened up, poaching intensifies in regions where Zaire ebolavirus and other pathogens are already significant threats. The extensive selective-logging regime applied over most of the Central Chimpanzee’s geographic range is leading to widespread habitat modification, while global warming is likely to cause additional changes in the extent and quality of habitats suitable for great apes. Global warming may also lead to increased exposure to novel pathogens, as Chimpanzees expand their diets to acquire adequate resources.



Conservation Actions [top]

Conservation Actions:

Pan troglodytes is listed on Appendix I of CITES and in Class A of the African Convention. National and international laws controlling hunting or capture of great apes exist in all habitat countries, but enforcement of protective legislation is inconsistent or lacking throughout much of the species’ range. Only around 33% of Central Chimpanzees and about 22% of their range are protected by forest guards, who work in most protected areas and in the well-managed logging concessions; the remainder of their range is unprotected and highly vulnerable to poachers.

Two targeted conservation action plans for the great apes of Western Equatorial Africa have been produced (Tutin et al. 2005, IUCN 2014). The areas where most of the world's Central Chimpanzees occur in geographically distinct blocks have been identified and a series of actions outlined for each, which can be broadly encapsulated as:

  1. An increase in effective law enforcement throughout the region, not only in protected areas, but also in logging concessions and unprotected swamp forests as only 14% of Central Chimpanzees occur in protected areas, with a further 8% in FSC-certified logging concessions.
  2. Effective, coordinated land-use planning to avoid the clearing of large areas of intact Chimpanzee habitat to establish large-scale agriculture, especially oil-palm plantations. Industrial extraction of other natural resources, namely timber and minerals, should be included in this holistic, spatially-explicit approach. Such planning needs to be done at both national and regional levels. Several of the most important areas for great ape conservation are transboundary, and thus fall under the remit of national agencies of two or three countries.
  3. Awareness-raising among all sectors that deal with land and the protection of natural resources: law enforcement and judiciary; protected area authorities; mining, logging, and agricultural industries; local communities and tour operators. This outreach effort should include specific information on minimising human impacts, such as avoidance of human disease transmission to great apes. IUCN best practice recommendations for logging companies regarding management that is compatible with great ape conservation (Morgan and Sanz 2007; Morgan et al. 2013) can be downloaded here: http://www.primate-sg.org/best_practice_logging
  4. Further research into ways of mitigating the spread and virulence of Ebolavirus, such as addressing the possibilities of administering vaccines that are non-detrimental to the target species (great apes) and other species that may come into contact with the vaccine, and that protect a sufficiently large and geographically-appropriate proportion of the great ape population to form barriers against its spread. IUCN disease prevention guidelines (Gilardi et al. 2015) are available here: http://www.primate-sg.org/best_practice_disease
  5. Long-term standardised monitoring of law enforcement efforts and effectiveness, of Chimpanzee abundance throughout their range, and of great ape health, particularly with respect to Ebolavirus. A standardised tool for law enforcement monitoring (SMART: http://www.smartconservationsoftware.org) is in use across much of the range; standard methods for surveying and monitoring great ape populations that facilitate more accurate and precise monitoring of changes in abundance have been in use for about a decade (Kühl et al. 2008 http://www.primate-sg.org/best_practice_surveys); and non-invasive diagnosis of a range of pathogens is now possible, for example, detection of Ebolavirus in faeces (Reed et al. 2014).

Maintaining large, intact and well-protected areas of forest will be key to maintaining great ape populations in the long term, and this can only be done by a combination of the actions detailed in the 2015–2025 IUCN Action Plan. Threats and conservation actions needed are outlined in greater detail in the action plans than is possible here. These documents can be downloaded at: http://www.primate-sg.org/action_plans


Citation: Maisels, F., Strindberg, S., Greer, D., Jeffery, K., Morgan, D.L. & Sanz, C. 2016. Pan troglodytes ssp. troglodytes. The IUCN Red List of Threatened Species 2016: e.T15936A17990042. . Downloaded on 06 December 2016.
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