This week’s Animal of the Week is the Eastern Lowland Gorilla, also known as Grauer’s Gorilla. Deep within the forests of the eastern Democratic Republic of the Congo lives an enormous but highly social great ape:
Its scientific name is Gorilla beringei graueri. It is one of the two subspecies of eastern gorilla; its close relative is the mountain gorilla (Gorilla beringei beringei).
Grauer’s gorillas are particularly remarkable because they are considered the largest living gorilla subspecies—and therefore the largest living primates in the world. Adult males can weigh more than 400 pounds.
Despite the name “lowland gorilla,” these animals aren’t restricted to low elevations. They inhabit forests ranging from roughly 600 to 2,900 meters (about 2,000 to 9,500 feet) above sea level, which is one reason the name Grauer’s gorilla is increasingly useful.
Quick Facts
Animal: Eastern Lowland Gorilla, also called Grauer’s Gorilla
Scientific Name: Gorilla beringei graueri
Animal Type: Mammal / Great Ape
Family: Hominidae
Diet: Primarily herbivore; occasionally consumes insects
Body Support: Endoskeleton
Group Name: Troop or band
Newborn Weight: About 4 pounds
Average Size: Adult males can reach approximately 5½ to 6 feet when standing upright; females are considerably smaller
Average Female Weight: Approximately 150 to 220 pounds
Average Male Weight: Approximately 350 to 450+ pounds; exceptionally large males can exceed 400 pounds
Average Lifespan: Approximately 35 to 40 years in the wild; gorillas can live longer in human care
Top Speed: Commonly estimated at approximately 20 to 25 mph for short bursts
Habitat: Tropical lowland, transitional and montane forests
Range: Eastern Democratic Republic of the Congo
Conservation Status: Critically Endangered
Mating Season: Year-round; no specific breeding season
Babies: Usually one infant following approximately 8½ months of pregnancy; twins are rare
Social Life: Highly social; typically lives in family groups containing a silverback, females, juveniles and infants
Grauer’s gorillas occur only in the eastern Democratic Republic of the Congo, making them one of the country’s unique native animals.
What Makes Them Special
Size is one of the most striking features of the Eastern Lowland Gorilla.
Adult males are extraordinarily muscular animals with massive shoulders, arms, jaws and hands. Mature males develop the distinctive silver-gray hair across their backs that earns them the name silverback.
Their massive jaws are supported by powerful muscles attached to prominent ridges on the skull. But those impressive jaws aren’t primarily designed for hunting—they help gorillas process enormous quantities of tough vegetation.
Like other gorillas, Grauer’s gorillas have arms that are considerably longer than their legs. They usually move using knuckle-walking, placing their weight on the knuckles of their curled hands.
They can stand upright and walk short distances on two legs, but four-legged locomotion is much more common.
Gorillas also possess individual fingerprints. Even more remarkably, the patterns and wrinkles around a gorilla’s nose are individually distinctive and can help researchers identify particular animals.
Their intelligence is equally impressive. Gorillas are capable of problem-solving, learning from other gorillas, manipulating objects, forming complicated relationships and remembering individuals.
Habitat
Eastern Lowland Gorillas are found only in eastern Democratic Republic of the Congo.
Their remaining range includes forests within and surrounding areas such as Kahuzi-Biega National Park, one of the most important remaining strongholds for the subspecies.
Despite “lowland” being part of their traditional name, Grauer’s gorillas occupy a surprisingly wide range of elevations—from roughly 1,968.50 to 9,514.43 ft (600 to 2,900 meters).
Their habitats include:
- Lowland tropical rainforest
- Transitional forest
- Montane forest
- Bamboo forest at higher elevations
- Regenerating secondary forest
Researchers have found that Grauer’s gorillas may make extensive use of regenerating forests, including areas associated historically with abandoned settlements or agricultural fields.
Large adults spend most of their time on the ground, although younger gorillas are considerably more willing to climb trees.
Diet
Eastern Lowland Gorillas are predominantly herbivorous.
Their diet includes:
- Leaves
- Stems
- Shoots
- Herbs
- Bark
- Vines
- Lianas
- Roots
- Seasonal fruits
- Bamboo at higher elevations
- Occasional insects
Their exact diet changes according to location, elevation and season.
Fruit becomes particularly valuable when available, but gorillas can survive largely on fibrous vegetation when fruit is scarce.
This requires a tremendous digestive system. A gorilla’s noticeably large abdomen isn’t simply body fat. Its digestive tract houses microorganisms that help break down the fibrous plant material making up much of its diet.
Eating fruit also gives gorillas an important ecological role. Seeds swallowed with fruit can eventually pass through the digestive tract and be deposited elsewhere, helping disperse plant species throughout the forest.
Behavior
Eastern Lowland Gorillas spend much of their day foraging, eating, resting, traveling and socializing.
Their enormous bodies require a substantial amount of food, meaning feeding occupies a large part of their daily routine.
Around midday, gorillas often rest. Youngsters may use this opportunity very differently from the adults—wrestling, chasing one another, climbing and playing while older animals relax.
Before nightfall, gorillas construct sleeping nests from surrounding vegetation.
These nests aren’t permanent bedrooms. A gorilla will generally construct another nest when it chooses a new sleeping location.
Infants initially sleep with their mothers before eventually constructing nests of their own.
Gorillas also possess a surprisingly rich communication system. Across gorillas, researchers have documented numerous vocalizations, including grunts, barks, roars, screams and other sounds. Body posture, facial expressions, touch and gestures provide additional ways of communicating.
And then there’s the famous chest beat.
A chest-beating gorilla isn’t automatically preparing to attack. Displays can communicate information to other gorillas and sometimes help prevent a confrontation from becoming a physical fight.
Social Life
Eastern Lowland Gorillas are highly social.
A typical family group may contain:
- One dominant silverback
- Additional adult or younger males
- Several adult females
- Juveniles
- Infants
Group composition can vary considerably.
The dominant silverback plays an essential role within the troop. Rather than simply being the strongest animal, he acts as a leader and protector.
He can influence where the troop travels and feeds, mediate disputes among group members, protect infants and confront potential threats.
Young gorillas spend years learning from their mothers and other troop members.
Play is especially important. Youngsters chase one another, climb, wrestle, tumble and interact with adults. These activities help develop coordination while teaching young gorillas how to behave within their social group.
As males mature, their relationship with the troop can change. Some eventually leave and live temporarily alone or with other males before establishing their own reproductive groups.
Mating
Eastern Lowland Gorillas can reproduce throughout the year rather than during a specific mating season.
Females usually become reproductively mature before males reach full physical maturity.
A female may actively initiate mating by approaching a male, maintaining eye contact or using other social signals.
After successful mating, pregnancy lasts approximately 8½ months, remarkably similar to human pregnancy.
Gorillas have one of the slowest reproductive rates among mammals. A mother typically has only one infant at a time and spends several years caring for that offspring before producing another.
That slow reproductive cycle becomes especially important when considering the conservation of Grauer’s gorillas. A population that loses many mature animals cannot quickly replace them.
Babies
A baby Eastern Lowland Gorilla is called an infant.
Females normally give birth to one infant, although twins occasionally occur.
A newborn gorilla weighs only around 4 pounds—astonishingly small compared with a massive adult silverback. Gorilla newborns possess a natural grasping reflex that allows them to cling to their mothers.
During the first few months, mothers provide extensive physical support while carrying their babies.
As infants grow stronger, they begin riding on their mothers’ backs, exploring their surroundings, playing with other youngsters and experimenting with solid foods.
Young gorillas remain dependent upon their mothers for several years.
This extended childhood is important because becoming a gorilla involves learning much more than finding food. Youngsters must learn how to communicate, recognize social relationships, respond to the silverback, find suitable foods, build nests and navigate their forest environment.
Silverbacks can also show remarkable tolerance toward youngsters. Adult males may allow young gorillas to climb on them, remain near them or interrupt their resting periods during play.
Conservation Status
The Eastern Lowland Gorilla is Critically Endangered.
Its limited geographic range makes conservation particularly important because every wild Grauer’s gorilla lives within the Democratic Republic of the Congo.
Research published in 2016 estimated that the population had declined by approximately 77% in a single generation, from an earlier estimate of roughly 17,000 animals to about 3,800. Researchers linked the decline particularly to armed conflict, illegal hunting and mining activity.
Those figures describe the documented historical decline rather than a precise 2026 population count.
Major threats include:
- Habitat destruction and fragmentation
- Illegal hunting and bushmeat
- Mining
- Snares
- Human conflict and political instability
- Disease
- Increasing human pressure on forests
Mining presents a particularly complicated conservation problem in eastern DRC. Remote mining operations can destroy habitat, while people working far from established communities may hunt wildlife for food.
Because females produce so few offspring during their lives, even a relatively small number of deaths can have long-lasting consequences for the population.
How You Can Help
Supporting reputable organizations working directly with gorillas and communities in the Democratic Republic of the Congo can contribute to habitat protection, anti-poaching work, scientific research and community conservation.
Recycling cell phones and other electronics can also help reduce demand for newly mined materials. Some minerals used in electronics are extracted in gorilla habitat within the Democratic Republic of the Congo, where poorly managed mining can contribute to forest destruction and wildlife hunting.
Consumers can also support responsibly sourced products and learn where materials such as tropical timber and minerals originate.
Protecting Grauer’s gorillas doesn’t benefit only the gorillas. Conserving their enormous forest habitat protects countless other species while preserving an ecosystem that local human communities also depend upon.
Final Fun Fact
🐾 Fun Fact: Eastern Lowland Gorillas have been observed wading into swampy forest clearings to feed on aquatic plants. While gorillas generally avoid deep water and aren’t known as swimmers, Grauer’s gorillas may deliberately enter shallow water to reach mineral-rich vegetation—showing just how adaptable these massive great apes can be when searching for food.
Sources
Primates in peril – conservationists reveal the world’s 25 most endangered primates | IUCN
African Wars Endanger World’s Largest Gorilla Subspecies | Smithsonian Institution