Eastern Lowland Gorillas – Eastern Gorilla of Kahuzi-Biega National Park

In the heart of the Eastern Democratic Republic of Congo’s lush forests, a fascinating yet critically endangered subspecies of gorillas, the Eastern Lowland Gorillas (Gorilla beringei graueri), make their home, captivating the imagination of wildlife enthusiasts alike.

The Democratic Republic of Congo, in central Africa, is the 2nd-largest African country and 11th-largest globally, covering 2,345,410 sq km (905,563 sq mi), roughly the size of five US states combined. It’s home to diverse wildlife, cultures, languages, and natural resources.

Grauer’s gorillas are concentrated in significant populations within various national parks, including Kahuzi Biega National Park, Maiko National Park, Tayna Gorilla Reserve, Usala Forest, and Itombwe Massif.

Additionally, other captivating locations and national parks are home to eastern lowland gorilla populations, such as Virunga National Park, which is renowned for its mountain gorillas, as well as Volcanoes National Park in Rwanda and Bwindi Impenetrable Forest National Park in southwestern Uganda, both of which are habitats for mountain gorillas. Mgahinga Gorilla National Park in Uganda is another notable location for mountain gorilla sightings.

With their remarkable intelligence, intricate social dynamics, and endearing gentle nature, Eastern Lowland Gorillas and their close cousins the Mountain Gorilla have long been compared to humans, with whom they share a strikingly close kinship.

This article invites you to venture into the captivating realm of these gentle giants, as we explore the intricacies of their habitat, genetic makeup, eastern lowland gorilla population dynamics, dietary preferences, social behaviors, and the concerted conservation efforts aimed at protecting these incredible gentle giants.

Eastern Lowland Gorilla Species and Genes

The following points outline key genetic and species classification information about eastern gorillas, as discussed in greater detail including Genetic makeup, Species classification, Taxonomy, and evolutionary history.

The Gorilla Subspecies

The Gorilla genus has two subspecies: eastern gorilla (Gorilla beringei) and western gorilla (Gorilla gorilla), found in Equatorial Africa, separated by the Congo Basin forest. They are further divided into four subspecies, including the eastern lowland gorilla, which shares 98.8% DNA with humans. The species classification is:

1. Kingdom: Animalia
2. Phylum: Chordata
3. Class: Mammalia
4. Order: Primates
5. Family: Hominidae
6. Genus: Gorilla
7. Species: G. beringei
8. Subspecies: G. b. graueri

The eastern lowland gorilla boasts a distinctive genetic signature, the “Grauer’s gorilla” haplotype, which distinguishes it from other gorilla subspecies like the separate subspecies of Mountain gorillas.

While research has uncovered genetic diversity within this subspecies, the overall diversity is surprisingly low compared to its cousins the Mountain Gorillas, likely a consequence of historical population fragmentation and habitat destruction.

The subspecies’ name, “Grauer’s gorilla,” pays homage to the pioneering Austrian zoologist and explorer Rudolf Grauer, who first identified this remarkable subspecies.

Physical Features of Eastern Lowland Gorillas /What Are Some Cool Facts About the Eastern Gorilla?

The Eastern Lowland Gorilla (Gorilla beringei graueri) is the largest of the four-gorilla subspecies, distinguished by its unique physical characteristics, which include;

a)   Eastern Lowland Gorilla Size and Weight Of Eastern Lowland Gorilla

Grauer’s gorilla, a subspecies of the eastern lowland gorilla, is the largest primate among the great apes, with impressive physical dimensions. Adult males (silverbacks) can grow up to 1.8 meters (6 feet) tall and weigh between 150-220 kg (330-485 lbs.), while females reach 1.6 meters (5.2 ft) in height and weight around 81 kg (178 lbs.).

b)   Facial Appearance and Features Of Eastern Lowland Gorilla

Males (silverbacks) have a distinctive appearance, characterized by:

1. A flat, broad face with a prominent forehead
2. A short snout (nose prints)
3. A noticeable crest on top of their head
4. Strong, large jaws with thick teeth
5. Dark, expressive eyes
6. A wide, flat nose

In contrast, females have narrower faces, differing from the males’ more robust features.

c)    Muscle Make Of Eastern Lowland Gorilla

Grauer’s gorillas possess a sturdy physique, characterized by:

• Stocky bodies
• Broad, expansive chests
• Strong and large powerful arms
• Sharp nails
• Relatively short legs
• Muscular, long arms with prominent shoulder muscles

Their robust build and impressive arm strength enable them to navigate their environment with ease and agility.

d)   Fur Color Of Eastern Lowland Gorilla

Grauer’s gorilla has a distinctive coat, characterized by:

• Thick, shorter fur
• Dark brown to jet-black coloration
• A subtle reddish-brown tint on their backs, adding a hint of warmth to their overall dark hue

Where Do the Eastern Lowland Gorillas Live?

The eastern lowland gorilla is a permanent inhabitant of the Eastern DRC, specifically in the Albertine Rift region.

The Eastern Lowland Gorillas tend to inhabit a diverse range of natural habitats, including higher altitudes, lowland forests, montane or mountainous forests, cloud forests, bamboo forests, and swamp forests.

The eastern lowland gorilla habitat is evenly distributed across the eastern DRC, encompassing areas such as the Virunga Mountains, Kahuzi Biega National Park, Virunga National Park, Maiko National Park, Tayna Gorilla Reserve, Usala Forest, Itombwe Massif, and provinces like North Kivu, South Kivu, and Maniema.

These gorillas reside in areas with elevations ranging from 600 to 3,300 meters above sea level, characterized by high rainfall (1,500-2,000 mm per year), high humidity (70-90%), cooler temperatures (10-15°C/50-59°F), steep terrain, and dense vegetation.

Population of Eastern Lowland Gorilla

As of 2006, the estimated total population of Grauer’s gorillas, also known as eastern lowland gorilla is approximately 3,800 individuals, with a population density of 0.4-1.7 individuals per square kilometer.

This makes them one of the most endangered subspecies of gorillas. Notably, eastern gorillas tend to be fewer in number compared to the western lowland gorilla kind.

According to a 2004 report, the population of eastern lowland gorillas declined from approximately 5,000 in the wild to fewer than 3,800 in 2016, whereas western lowland gorillas have a significantly higher population of over 100,000 individuals.

What Fruits Do Eastern Lowland Gorillas Eat?

Eastern Lowland Gorillas are herbivores with specific dietary needs, which they meet through a varied diet consisting of fruits, leaves, shoots, roots, and bamboo.

Their digestive system is specially adapted to break down cellulose, allowing them to thrive on a high-fiber, low-protein diet.

Interestingly, wild gorillas do not eat banana fruits but may damage banana trees to access the nutritious pith. Their diet includes:

• Fruits (5-10%): Wild fruits, cultivated fruits, Wild celery
• Leaves (60-90%): Bamboo shoots, leafy greens, and fruits
• Shoots (5-15%): Bamboo shoots and other plant shoots
• Roots and tubers (1-5%): Wild potatoes, underground plant parts
• Bamboo (1-5%): Stems, seeds
• Water: from natural sources
• Eat Insects: occasionally consumed

Eastern Lowland Gorilla Growth Chart

Eastern Lowland Gorillas reach maturity between 12-15 years old, with various age and maturity dynamics as follows:

1. Infancy (0-3 years): Born after an 8.5-month gestation, weighing 1.5-2.5 kg (3.3-5.5 lbs.), relying solely on mother’s milk, starting solids at 4-6 months.
2. Juvenescence (4-6 years): Weaned from mother’s milk, learning essential skills like foraging and social behaviors, and becoming more independent.
3. Sub-adult (7-12 years): Physically and socially developing, silverbacks or males depart from their mother’s group to join other family groups, while females may stay in their natal group or join another.
4. Adulthood (13-50 years): Physical and sexual maturity stage, dominant males (silverbacks) develop silver saddle-shaped patches, and females reach reproductive maturity, giving birth every 6-8 years.
5. Senior (51+ years): Older males lose dominant status, females experience reproductive decline, and both sexes may experience physical decline or shrinkage.

Behaviors of Eastern Lowland Gorillas

The Eastern Lowland Gorilla exhibits various social characteristics and behaviors, including hierarchical structures, with dominant and subordinate roles, effective communication through vocalizations, gestures, and facial expressions, and cooperative behavior, such as collaborative problem-solving, and playful interactions, essential for social bonding and development.

Social Hierarchy

Eastern Lowland Gorillas live in stable family groups, known as troops or bands, typically consisting of 5-30 individuals.

These troops are organized in a harem structure, led by a dominant male, or silverback, who is responsible for protecting and defending the group.

The social hierarchy within these troops is complex. The dominant male (silverbacks)  is at the top, followed by subordinate males, adult females, juveniles, and young eastern lowland gorillas.

1. The silverback, often the largest and strongest, leads the group and is polygamous, mating with multiple females.
2. Subordinate males, often younger or weaker, may challenge the dominant male or leave to form bachelor groups.
3. Multiple or several females, often related, form close bonds and play a crucial role in group stability and reproduction.
4. Juveniles, offspring of older females, learn essential skills from adults and are playful and curious.
5. A Newborn Gorilla, is completely dependent on its mother, which can also be seen in the troops.

This hierarchical structure maintains social order, ensures group survival, protection, stability, and nurturing, and develops skills and social behaviors, preparing wild gorillas for future roles.

Notably, some troops are led by a dominant female, particularly in Grauer’s gorilla.

Social Relationships

Eastern lowland gorillas are renowned for their intelligence and social nature, earning them the nickname “gentle giants.” Their social relationships and interactions are built on:

1. Social Bonding: Gentle touching, embracing, and grooming strengthen social bonds.
2. Cooperation: Troop members work together to achieve common goals, like foraging and defending against threats.
3. Empathy: Remarkable empathy and altruism are displayed, comforting and helping each other in distress.
4. Affiliation: Close relationships are formed with specific group members, spending time near each other.
5. Social Learning: Young gorillas learn essential skills and behaviors by observing and imitating adults.
6. Play: Playful activities like chasing, tickling, and somersaulting contribute to social bonding.
7. Conflict Resolution: Various strategies are used to resolve conflicts, including reconciliation and mediation.
8. Resting And Relaxation: Breaks are taken together, resting in a close group to socially bond.
9. Exploration: Curiosity drives them to investigate their environment, exploring new sights, sounds, and smells.

Communication Methods

Eastern gorillas employ a range of communication strategies to convey information, express emotions, and maintain social bonds within their groups. These include:

1. Vocalizations: Various calls such as roars (long-distance alerts), grunts (intimate sounds), chirps (high-pitched excitement or alarm), and humming (soft comfort or reassurance).
2. Facial Expressions: Relaxed (open mouth, relaxed lips), tense (pursed lips, furrowed brow), and fearful (wide eyes, open mouth) faces.
3. Body Language: Posture (standing, slouching, or crouching), proximity (physical closeness or distance), and orientation (facing or turning away from others).
4. Touch: Grooming (gentle touching, stroking, or cleaning), embracing (wrapping arms around each other), and play-fighting (gentle wrestling or tickling).
5. Visual Displays: Chest-beating (drumming on the chest with fists to show dominance) and branch-shaking (shaking branches to signal excitement or alarm).
6. Olfactory Communication: Scent marking, leaving pheromones on objects or individuals to territory mark.

Through these diverse communication strategies, Grauer’s gorillas effectively share information, articulate emotions, and foster strong social connections, nurturing cohesive bonds within their groups.

Cognitive Abilities

Eastern gorillas are renowned for their impressive intellectual abilities, which often lead to comparisons with humans. Their cognitive skills are truly remarkable, encompassing:

1. Resourceful Problem-Solving: Using tools to extract food or navigate their environment.
2. Exceptional Memory and Recall: Recognizing individual group members even after long separations.
3. Self-Awareness: Demonstrating a clear understanding of their own identity and individuality.
4. Spatial Awareness: Navigating complex habitats with ease, remembering food sources and shelter locations.
5. Adaptive Cognitive Flexibility: Adjusting behavior through imitation or replication of actions observed in others.
6. Innovative Problem-Solving: Creating new solutions to problems, showcasing their creativity and ingenuity.

The intricate social dynamics of eastern gorillas reveal a sophisticated society, underscoring their exceptional intelligence, emotional intelligence, and adaptability to their environment.

Eastern Lowland Gorilla Gestation Period

Eastern Lowland Gorillas take approximately 8.5 months, similar to humans and other gorilla subspecies.

This extended gestation is likely due to their large size, complex brain development, and advanced physical abilities. The gestation pattern in eastern gorillas follows a specific sequence:

• Conception: Silverback mates with females during their fertile window
• Implantation: Occurs shortly after mating
• Embryonic development: Begins 2-3 weeks after implantation
• Fetal development: Lasts approximately 6-7 months
• Birth: Young gorilla born after 8.5 months of gestation

Females typically give birth to a single young eastern lowland gorilla, which they nurse for about three years. Infants develop quickly, crawling at nine weeks and walking at 35 weeks.

They stay with their mother for several years before maturing. Females typically have 2-6 offspring in their lifetime, with a significant interval between births.

Individual factors can influence the gestation pattern, but overall, eastern gorillas have a remarkable reproductive process.

Why Is the Eastern Lowland Gorilla Endangered?

Grauer’s gorillas are critically endangered due to numerous threats, including:

1. a)   Habitat Loss

Devastating fires, charcoal production, logging, infrastructure development, deforestation, and agricultural expansion have led to habitat destruction and fragmentation, leaving eastern gorillas without natural habitats, reducing food availability, and increasing isolation, disease spread, and vulnerability to climate change.

1. b)   Poaching

Gorillas are hunted for bush meat, and infants are captured for the illegal pet trade, leading to a rapid decline in eastern lowland gorilla numbers.

1. c)    Epidemics And Disease Transmissions

Outbreaks of diseases like Ebola and COVID-19, as well as increased risks of transmission from human activity, have resulted in numerous deaths among gorilla populations in the Democratic Republic of the Congo.

1. d)   Climate Change

Rising temperatures and changing precipitation patterns have altered the natural habitat and food availability of Grauer’s gorillas, posing a significant threat to their existence.

1. e)    Human-Gorilla Conflict

As natural habitats overlap with human settlements, gorillas raid crops or damage property, leading to retaliation and sometimes deadly consequences.

1. f)     Mining And Drilling

Timber extraction, mining, and drilling by artisanal miners have caused extreme damage to gorilla habitats, disrupted behavior, and led to deforestation, destroying natural habitats.

1. g)   Civil Unrest and Political Instability

Civil wars and armed groups in the Democratic Republic of Congo have resulted in a rapid decline in eastern gorillas, as military groups occupy and fight in their habitats for extended periods.

Civil unrest has led to a significant decline in eastern gorillas, and the reasons for this are manifold.

• Firstly, militia groups in the Eastern Lowland gorilla habitat have led to habitat destruction. These groups engage in logging, illegal mining, and agriculture, causing habitat loss and fragmentation.
• Secondly, poaching is another major threat. Rebels in the forests hunt and kill gorillas for bushmeat and illegal trade, significantly reducing their numbers. Moreover, conflicts disrupt food supplies, leading to malnutrition and increased poaching, which further threatens gorillas.
• Thirdly, conservation efforts are hindered by armed conflict. Conservation activities, research, and monitoring are challenging due to the presence of armed groups, posing a significant threat to gorilla habitats. Furthermore, conflict diverts funding and resources away from conservation efforts, as funders face limitations in accessing gorilla habitats during civil unrest.
• Lastly, disease transmission is a concern. Proximity between humans and gorillas during civil unrest leads to increased transmission of diseases, which can be deadly for gorillas. Additionally, population fragmentation makes certain gorilla groups more vulnerable to extinction due to low reproduction rates.

To address these threats and protect the eastern lowland gorillas, collaborative conservation, research, and support are essential.

Conservation Status

Conservation efforts are in full swing to protect the critically endangered species of eastern lowland gorilla and its habitats, thanks to the tireless work of organizations like the IUCN, the Dian Fossey Gorilla Fund International, and the World Wildlife Fund.

These organizations are making a real difference by monitoring populations, protecting habitats, and engaging local communities in conservation efforts.

The Democratic Republic of the Congo government is also stepping up to the plate, working closely with these organizations to establish protected areas, raise awareness, and enforce laws that prevent gorilla capture, hunting, poaching, and other harmful human encroachment near habitats.

Together, they’re ensuring the legal protection of these incredible animals and the preservation of their habitats guarded by park guards.

FAQ [Frequently Asked Questions]

1)     How Many Eastern Gorillas Are Left? /How many Eastern lowland gorillas are left in the world in 2025?

With a dwindling population of less than 6,000, the eastern lowland gorilla is teetering on the edge of extinction, classified as Critically Endangered.

2)      Are Eastern Gorillas Bigger Than Western Gorillas?

Eastern lowland gorillas are distinguished by their larger size, with mature males weighing up to 220 kg (484 lbs.) and females reaching approximately 80 kg (176 lbs.), making them slightly larger than the western species.

3)     Do Eastern Lowland Gorillas Have Any Predators?

The primary threat to Eastern lowland gorillas is not from other animals, but from humans. While adult gorillas may occasionally face predation from leopards and crocodiles, human activities pose the most substantial danger to their well-being and survival.

4)     Are Eastern Lowland Gorillas Aggressive? 

They are typically gentle and not aggressive unless they feel threatened, or scared or when protecting their habitats and territory.

5)     What Is Special About Eastern Lowland Gorillas?

They are special because they’re the largest of all gorilla subspecies, with distinctive thick, dark, and short fur and stocky bodies.

6)     Are Eastern Gorillas Silverbacks?

The male adult eastern gorillas or mountain gorillas are what we call silverbacks.

7)     Why Should We Save Eastern Gorillas? /Why Should Eastern Gorillas Be Saved?

Gorillas play a vital role in seed dispersal and other ecosystem functions that benefit the humans and environment in several ways such as keeping climate and food chains stable, tourism boosting economies, etc.

What Would Happen If Eastern Lowland Gorillas Became Extinct?

If eastern lowland gorillas become extinct, it would lead to increased vulnerability to climate change, disruption of the food chain and ecosystems, setbacks for conservation efforts and scientific research, etc.

Get ready to encounter the impressive Eastern Lowland Gorillas, the largest gorilla subspecies, in their natural habitat in the Democratic Republic of Congo. Despite numerous challenges, these gentle giants remain a sight to behold. Let Prime Safaris and Tours Ltd take you on an unforgettable journey to explore their world. Visit DRC today and witness the majesty of these incredible creatures!