Africa’s Gorilla Subspecies — Beyond the Mountain Gorilla
When gorilla trekking is discussed, “gorilla” almost invariably means mountain gorilla — the subspecies found in Rwanda, Uganda, and Congo’s Virunga range and at Bwindi in Uganda. But the gorilla genus (Gorilla) contains two species and four recognised subspecies, and the conservation status, distribution, and ecology of each provides context that makes the mountain gorilla’s specific situation more precisely understood. This guide covers all four subspecies, their ranges, their populations, and their current conservation challenges.
Mountain Gorilla — Gorilla beringei beringei
The mountain gorilla is the best-known of the four subspecies globally — the subject of Dian Fossey’s research, the primary gorilla trekking species, and the flagship species for conservation funding in the Albertine Rift. The global population of approximately 1,063 individuals (2018 census) is distributed between the Virunga range (shared by Rwanda, Uganda, and Congo) and the Bwindi-isolated population in southwest Uganda. The mountain gorilla is the only gorilla subspecies that cannot survive in captivity — no mountain gorillas exist in zoos anywhere in the world. Every mountain gorilla on earth is wild, in the mountains of central Africa, within a protected area system that has grown more effective over the past three decades. The population trend is positive — the only gorilla subspecies for which that statement is consistently true.
Eastern Lowland Gorilla — Gorilla beringei graueri
The eastern lowland gorilla, also called Grauer’s gorilla, is the largest of the four gorilla subspecies by body size — dominant males exceed 200 kilograms in the wild — and is endemic to the Democratic Republic of Congo, primarily in North and South Kivu provinces and the adjacent highland forests. The eastern lowland gorilla’s population has collapsed dramatically over the past thirty years as a consequence of armed conflict in eastern Congo, the bushmeat trade enabled by military presence, and the mining activity that has driven forest clearance and infrastructure development across the gorilla’s range. Current population estimates range from 3,500 to 6,800 individuals — a wide uncertainty range that reflects the difficulty of conducting census surveys in areas of active armed conflict — down from an estimated 17,000 in the 1990s. The eastern lowland gorilla is Critically Endangered.
Western Lowland Gorilla — Gorilla gorilla gorilla
The western lowland gorilla is the most numerous of the four gorilla subspecies and the most widely distributed — found across Cameroon, Central African Republic, Republic of Congo, Gabon, Equatorial Guinea, and the Democratic Republic of Congo’s western areas. It is the subspecies most commonly seen in zoos worldwide, where captive breeding programmes maintain a genetically managed population. The wild population is estimated at approximately 95,000–100,000 individuals, but the western lowland gorilla is classified as Critically Endangered because the population has declined by more than 60% over the past two to three decades as a consequence of Ebola virus disease outbreaks (which have killed gorillas in the same way they kill humans), the commercial bushmeat trade, and ongoing forest clearance for agriculture and mining throughout the subspecies’ range.
Cross River Gorilla — Gorilla gorilla diehli
The Cross River gorilla is the most threatened of all four gorilla subspecies — a population estimated at approximately 200–300 individuals confined to a small cluster of forests in the highland region where Nigeria and Cameroon share their border, near the Cross River from which it takes its name. The Cross River gorilla is the least studied of the four subspecies, partly because the fragmented forest patches it inhabits are difficult to access, and partly because the small population has proved resistant to habituation — there are no habituated Cross River gorilla groups available for research or tourism. The Cross River gorilla faces extinction threats from forest clearance for agriculture, hunting (even with protected status), and the very small population size that makes inbreeding and demographic stochasticity significant risks to the gene pool’s long-term viability.
