Gorillas are the world’s largest primates, divided into two species and four distinct subspecies. All wild populations are exclusively found in the tropical and subtropical forests of equatorial Africa. The geographic distribution is separated by approximately 900 kilometers, with the Congo River forming a significant natural barrier. This isolation has led to separate evolutionary paths, resulting in the Western and Eastern gorilla species, each with unique adaptations.
Western Gorillas: Geographic Range and Subspecies
The Western Gorilla species (Gorilla gorilla) consists of two subspecies found in Central West Africa. The Western Lowland Gorilla (Gorilla gorilla gorilla) is the most numerous and widely distributed of all four subspecies.
Its range spans a vast area of the Congo Basin, encompassing countries like Gabon, the Republic of the Congo, Equatorial Guinea, Cameroon, and the Central African Republic. These gorillas primarily inhabit lowland tropical rainforests, swamp forests, and marshlands, living at elevations up to 1,600 meters. Their ability to thrive in remote, dense swampy areas has historically offered some protection. They are generally smaller and have a slightly browner coat and a reddish crown compared to their eastern relatives.
The second subspecies is the critically endangered Cross River Gorilla (Gorilla gorilla diehli), which has the most restricted range of any gorilla. This small, isolated population is found only in a rugged, hilly forest region along the border of Nigeria and Cameroon. Their habitat consists of fragmented patches of lowland and submontane forest, largely concentrated around the headwaters of the Cross River. This subspecies is separated from the Western Lowland Gorillas by roughly 300 kilometers, including the Sanaga River.
Eastern Gorillas: Geographic Range and Subspecies
The Eastern Gorilla species (Gorilla beringei) is confined to the forests of East Central Africa. Grauer’s Gorilla, also known as the Eastern Lowland Gorilla (Gorilla beringei graueri), is endemic only to the eastern Democratic Republic of Congo (DRC). This subspecies is the largest of all gorillas and lives in a wide altitudinal range, from lowland tropical rainforests to montane forests, between 600 and over 3,300 meters.
Their remaining stronghold is primarily within the Kahuzi-Biega National Park and Maiko National Park, as well as the Itombwe Massif in the eastern part of the country. The other subspecies is the Mountain Gorilla (Gorilla beringei beringei), which occupies two small, isolated, high-altitude forest regions. They live exclusively in the Afromontane cloud forests at elevations typically ranging from 2,200 to 4,300 meters. The first population is found in the Virunga Massif, a chain of volcanic mountains spanning the borders of Rwanda, Uganda, and the DRC. The second population is located entirely within Uganda, residing in the Bwindi Impenetrable National Park.
Conservation Status and Ecological Threats
The restricted and often fragmented geographic ranges of all gorilla subspecies contribute significantly to their vulnerability. Three of the four subspecies—the Western Lowland, Cross River, and Grauer’s Gorillas—are classified as Critically Endangered. The Mountain Gorilla is classified as Endangered, a result of decades of intensive, transboundary conservation efforts that have allowed its population to slowly increase.
Habitat destruction is a pervasive threat across all ranges, driven by deforestation for agriculture, logging, and infrastructure development. For Grauer’s Gorillas in the eastern DRC, this threat is exacerbated by the ongoing civil unrest and the proliferation of illegal mining camps, which fuel intense poaching for bushmeat and trophies. The instability in this region has made park enforcement extremely difficult, leading to a severe population decline.
Disease represents another major ecological threat, particularly for the Western Lowland Gorilla, whose populations have been devastated by outbreaks of the Ebola virus. The virus has caused massive die-offs in the Congo Basin, with some estimates suggesting a loss of over 60% of the population in the last two decades. The extremely small and fragmented population of the Cross River Gorilla is vulnerable to genetic bottlenecks and the threat of snares set by hunters.
Conservation strategies are therefore highly localized and focus on increasing the connectivity of habitats and strengthening anti-poaching patrols. Successful models, like the collaborative transboundary management in the Virunga Massif, demonstrate that intensive monitoring, veterinary care, and community engagement can lead to population stabilization and growth, even in politically volatile regions. Protecting these forest ecosystems is the primary action for the long-term survival of all gorilla subspecies.