Classification and Species

Mountain gorillas (Gorilla beringei beringei) are a subspecies of the eastern gorilla (Gorilla beringei). There are two subspecies of eastern gorilla: the mountain gorilla and the Grauer’s gorilla (also called the eastern lowland gorilla, Gorilla beringei graueri), found only in the DRC. Mountain gorillas are the larger of the two and live exclusively at high altitude.

Gorillas are one of the four great apes, alongside chimpanzees, orangutans, and bonobos. They share approximately 98.3% of their DNA with humans — making them our closest relatives after chimpanzees.

Physical Characteristics

Mountain gorillas are the largest living primates. Adult males, known as silverbacks, typically weigh between 160 and 220 kilograms and stand around 170 centimetres tall when upright. Females are significantly smaller, averaging 70 to 100 kilograms.

The name “silverback” refers to the distinctive saddle of silver-grey hair that develops on a male’s back as he reaches full maturity at around 12 to 13 years of age. The silverback is the dominant member of the group — he makes all major decisions, settles disputes, and is responsible for the safety of every individual in the family.

Mountain gorillas have longer, thicker fur than other gorilla subspecies, an adaptation for surviving the cold temperatures of their high-altitude habitat, which ranges from 2,200 to 4,300 metres above sea level.

Diet and Feeding Behaviour

Mountain gorillas are almost entirely herbivorous. Their diet consists of leaves, stems, bark, roots, and wild celery — particularly the pith and leaves of plants like Galium, Urera, and wild banana. Fruit is rarely available at their altitude and forms only a very small part of their diet, unlike their lowland relatives.

An adult silverback consumes up to 34 kilograms of vegetation per day. Gorillas spend the majority of their waking hours — roughly six hours daily — feeding. They rarely need to drink directly from water sources because the plants they eat contain enough moisture to keep them hydrated.

Groups forage across a home range that shifts seasonally. Rangers track each habituated family daily, recording their sleeping position the previous evening and following their trail from first light.

Social Structure

Mountain gorillas live in stable family groups of five to thirty individuals, typically built around one dominant silverback. A group includes adult females, juveniles, infants, and sometimes one or two younger males called blackbacks.

Gorillas are peaceful animals within their family group. Aggression is rare and usually consists of displays — chest-beating, charging, vocalising — rather than physical contact. A silverback’s charge is almost always a bluff designed to warn off threats rather than an actual attack.

Infants are born after an 8.5-month gestation period and weigh around 1.8 kilograms at birth. They cling to their mother’s chest for the first several months before transitioning to riding on her back. Gorillas have a slow reproductive rate — females give birth roughly every four years, and infants stay close to their mothers for up to five years.

Intelligence and Communication

Mountain gorillas are highly intelligent and demonstrate tool use, problem-solving, and the ability to learn sign language in captivity. In the wild, their communication includes at least 25 distinct vocalisations — including grunts, belches (a contentment sound), screams, roars, and the iconic chest-beat, which functions both as a display to other males and as an announcement of location within the forest.

Gorillas build a new nest each night, either on the ground or in low tree branches, from folded vegetation. They sleep in these nests in family clusters, which rangers use to locate the group each morning.

Conservation Status

Mountain gorillas are listed as Endangered on the IUCN Red List. Their population has grown steadily over the past three decades — from around 620 individuals in 1989 to over 1,063 today — making them one of the few great ape populations that is increasing rather than declining.

This recovery is the direct result of intensive conservation work: anti-poaching patrols, veterinary intervention for sick or snared animals, community benefit-sharing programmes, and the revenue generated by gorilla trekking permits. The $700 (Uganda) and $1,500 (Rwanda) permit fees fund ranger salaries, park management, and community projects in the villages surrounding the forest.

The primary ongoing threats to mountain gorillas are habitat encroachment, snaring (gorillas are rarely the target but become bycatch in snares set for other animals), and disease transmission from humans — which is why strict health rules apply to all visitors.