March Primate of the Month — Chimpanzee Subspecies

Chimpanzees
Chimpanzees are the most abundant of the Great Apes, both in number and geographic range. The four subspecies have a combined population of 172,000-300,000 individuals left in the wild, which occupy a geographic range of 2.5 million km²! Even though there may not be considerable physical differences between the different subspecies, primatologists have identified the four subspecies based on genetic variance between different populations. As with any wild animal taxonomical research, future data may increase or decrease the number of formally recognized subspecies.
Within the Primatology world, much still remains unknown about Chimpanzee subspecies taxonomy and how these genetic differences manifest in broader physical and behavioral traits. Certain ‘cultural’ differences between varying groups of chimpanzees have been identified, ranging from particularities with food foraging, nest building, tool use, ‘language’ and much more.
Chimpanzees across the board face the same general threats: habitat fragmentation and destruction, poaching and the illegal pet trade, and disease transmission as they come in more frequent contact with humans. Of course, each population group has their own specific risks and perils, for example the impact of country wide unrest on the Eastern Chimpanzees living in D.R.Congo. For this reason, subspecies and regionally specific plans must be enacted in each case to ensure the survival of each population by mitigating local hazards.
Due to the increasing amount of deforestation and subsequent habitat fragmentation, it’s likely that subspecies populations will become more isolated from each other. This would lead to distinctions between these groups being magnified, making each subspecies more idiosyncratic and unique. You can read more about these distinctions with our recent blog post here.


The Four Chimpanzee Subspecies

Western Chimpanzee (Pan troglodytes verus)
IUCN Status: Critically Endangered
Population: 18,000 – 65,000 wild individuals
Range: West Africa from Senegal to Ghana
Habitat: Dry and moist lowland tropical forests
Key Threats: Habitat loss and fragmentation particularly due to palm-oil development in Sierra Leone and Liberia, and extractive industries in their home ranger; Poaching also poses a significant threat.

Nigeria-Cameroon Chimpanzee (Pan troglodytes ellioti)
IUCN Status: Endangered
Population: Fewer than 6,000-9,000 wild individuals
Range: Found only in Nigeria and Cameroon, north of the Sanaga River
Habitat: Primary and secondary moist lowland forest, montane and submontane forest
Key Threats: Poaching in the greatest threat, particularly the sale of bushmeat; Habitat loss due to agriculture and fire further endanger the Nigeria-Cameroon Chimpanzee.

Central Chimpanzee (Pan troglodytes troglodytes)
IUCN Status: Endangered
Population: Approximately 140,000 wild individuals
Range: Ranges from Cameroon to the Congo River (D.R.Congo). Largest of the subspecies at 700,00 km2
Habitat: Moist lowland tropical forests and swamp forests
Key Threats: Illegal poaching for bushmeat (facilitated by logging access roads); Disease transmission is also significant, especially with recent Ebola Virus outbreaks around their natural range.

Eastern Chimpanzee (Pan troglodytes schweinfurthii)
IUCN Status: Endangered
Population: 181,000–256,000 wild individuals
Range: From Congo River eastward to Tanzania and South Sudan, majority live in D.R.Congo
Habitat: Submontane and lowland tropical forests
Key Threats: Long-term civil unrest and lack of development in D.R.Congo has meant that poaching for bushmeat is one of the greatest threats, as well as habitat loss and degradation due to large-scale precious mineral mines throughout the country.