Western Lowland Gorilla

Quick Take

• A gorilla once held a conversation using over 1,000 words, and what she revealed about animal emotions changed everything. Sign language capacity →
• Humans and gorillas share 98% of their DNA, yet something in that tiny 2% gap makes a common cold potentially fatal for gorillas. Disease vulnerability explained →
• A silverback's authority over his group goes far beyond just fighting, and his daily decisions reveal a surprisingly complex social structure. Silverback social structure →
• Despite a population of roughly 100,000, this gorilla remains critically endangered, and the reason why is more unsettling than you'd expect. Population and endangerment →

The Western Lowland Gorilla is an intelligent animal sharing 98% of its DNA with that of humans. Perhaps the most famous Western Gorilla of all time is Koko, the gentle great ape who learned American Sign Language and taught the world that animals have thoughts and feelings too. Koko had a vocabulary of around 1,000 words — similar to that of a human toddler. She also shared a love of cats with her human friends and had several pet cats throughout her lifetime. Koko was believed to represent what language humans may have spoken ten million years ago. That was when gorillas and humans diverged in evolution — each following its own path.

Incredible Western Lowland Gorilla Facts

• We share around 98% of our DNA with gorillas. Despite our similarities, even the common human cold can have a detrimental impact on gorillas; they don’t have the necessary immunity to ward off something so simple.
• The Western Lowland Gorilla has the smallest family group of gorillas, with an average of 4 to 8 members. Other gorilla species may have up to 30 to 50 members in a group.
• Western Lowland Gorillas walk on all fours and use knuckles to carry the weight of their heads and torsos.
• Female Western Lowland Gorillas are able to give birth at 10 years old.
• The Western Lowland Gorilla is very intelligent and can even learn to use sign language to communicate with people and other gorillas.

Evolution

Although not much is known about the evolution of gorillas, they are closely related to humans and chimpanzees. Gorillas diverged from the human-chimpanzee lineage around 8 to 10 million years ago, while humans and chimpanzees split from their common ancestor approximately 7 to 13 million years ago — a notably wider range of estimates. Human gene sequences differ from gorilla sequences by only 1.6% on average.

Gorillas were previously thought to be a single species with three subspecies (Western lowland, eastern lowland, and mountain gorillas), but it is now agreed that there are two main species, the Western gorilla (Gorilla gorilla) and the Eastern gorilla (Gorilla beringei), and they each have two subspecies. Western and Eastern gorillas split into two groups at least 150,000 years ago.

Classification and Scientific Name

The scientific name of the Western Lowland Gorilla is Gorilla gorilla gorilla, and they are the smallest of the gorilla subspecies, weighing anywhere from 220 to 400 pounds.

The etymology of the word gorilla derives from the word ‘gorillai’, a Greek translation of Periplus of Hanno, written in Punic. It describes a tribe of hairy people. The Punic word for gorilla that the Greeks borrowed is, in turn, itself borrowed from a language native to West Africa. The Mpongwe of Gabon call the gorilla ‘G’guyla’, and the Fang call them ‘N’gil’.

Appearance

Compared to other gorilla subspecies, the Western Lowland Gorilla is smaller and weighs less. Males weigh anywhere from 300 to 500 pounds, while their Eastern counterparts weigh 300 to 485 pounds.

The height of the Western Lowland Gorilla ranges from about 4 feet 5 inches to 5 feet 1 inch, ranging from a child’s height to just above the average adult human height. Like other great apes, these gorillas have opposable thumbs, making using tools and other activities much easier.

They have wider skulls than other gorillas, and their brow ridges are more pronounced. It is also far easier to distinguish the females from males in Western Lowland Gorillas, as the females are almost half the size of silverbacks.

The Western Lowland Gorilla’s hair is a brown-gray color, with a little bit of red or auburn on top of its head. Male Western Lowland Gorillas have a patch of whitish hair that extends to their thighs, hence the name Silverback.

Behavior

The Western Lowland Gorilla is primarily a peaceful animal that prefers to avoid conflict. However, the dominant male will show signs of aggression to protect the group from outsiders. When offspring mature, they are ready to leave the group they were born into and find a mate.

This happens when the female is about eight years old and chooses the leader they want to join based on the range of their territory and the lead silverback’s size. When males mature, they either try to replace the silverback in an established group or spend a few years on their own until a few unrelated females join the male.

A silverback male has breeding rights to all the females, but he also allows the other males who haven’t reached maturity to mate with the females as well. As the leader of the group, he chooses what time they eat, what time they wake up, what time they go to sleep, the area where they live, and takes care of any disputes the group members may have with each other.

These gorillas never attack unless they are provoked, but males do fight over females, and when there is a new leader in the group, he will kill unrelated infants. When there is an aggressor or a challenger, an adult male will stand on his legs, roar, and scream while slapping his chest. If the intruder doesn’t get the message or ignores it, this will result in the male throwing his head back several times and then charging on all fours toward the intruder.

Habitat

In the wild, the Western Lowland Gorilla lives in the tropical rainforests of western Africa. The range of these animals includes the countries of Cameroon, Gabon, Angola (Cabinda Province), Central African Republic, Democratic Republic of the Congo, Republic of the Congo, and Equatorial Guinea. The territory of the Western Lowland Gorilla spans more than 270,000 square miles.

Diet

The Western Lowland Gorilla is largely an herbivorous animal with over 100 fruit species recorded in their diet, as well as shoots, leaves, and pith. When the fruit is scarce during the drier months, they also eat bark, nuts, pulp, wild cherry, roots, termites, lizards, and weaver ants. A fully grown adult male has the capacity to eat around 40 pounds of vegetation per day, which is around 10% of his body weight. For perspective, a 5-gallon bottle of water, a mid-size microwave, four 10-pound bags of potatoes, and an average 3-year-old child all weigh about 40 pounds.

Predators and Threats

The critically endangered Western Lowland Gorilla has very few threats in the wild, other than leopards and crocodiles. The main threats to the gorillas come from humans through habitat loss, disease, and poaching.

Due to habitat loss, humans clear-cut the trees gorillas live among. Humans use trees for mining, developing human settlements, and logging. In turn, logging roads make it easy for poachers to drive into the gorillas’ habitat and kill the gorillas to sell as high-priced bush meat for wealthy consumers. They also make ashtrays out of gorilla hands, and other body parts are turned into trinkets as well.

Gorillas are vulnerable to diseases and illnesses that humans easily fight off. This is because they haven’t developed the immunities that humans have. As a result, the common cold that humans get at least once a year can kill a gorilla. This also means that visitors who are carriers of contagious illnesses, such as the coronavirus, cannot get too close to gorillas, or they must wear a mask and sterile gloves.

Reproduction, Babies, and Lifespan

Unlike some animals in the wild, the Western Lowland Gorilla does not quickly reach the age when they begin to breed. Females don’t reach breeding age until they are 10 years old, and males don’t reach breeding age until they are 15 to 20 years old. The lifespan of these gorillas is 50 years or more, both in the wild and in captivity.

The gestation period for the Western Lowland Gorilla is similar to that of humans and lasts for nine months. Females typically give birth to a single offspring, with twins being rare. At birth, the baby gorilla weighs four pounds and can do little except cling to its mother. When they reach four months of age, they start to ride on their mother’s backs everywhere until they are three years old.

The infant mortality rate among the Western Lowland gorillas is high. Typically, a female gorilla gives birth around every 4 years, becoming pregnant around the time her previous offspring no longer rides on her back. With a lifespan of 50 years and giving birth every four years, the female gives birth to around 10 babies in her lifetime, with only two or three surviving to adulthood.

Population

The habitat of Western Lowland Gorillas makes it difficult for scientists to accurately determine how many of them are left in the wild. However, scientists believe that the total population is close to 100,000 individual gorillas. While it may seem like a relatively high number, the Western Lowland Gorilla is listed as critically endangered.

In Zoos

The Western Lowland Gorilla is actually one of two subspecies of gorilla found in Western Africa. The other subspecies of Western Gorilla is the Cross River gorilla, which is rare. Of all of the gorilla subspecies, the Western Lowland Gorilla is the most common gorilla subspecies found in zoos.

The Atlanta Zoo was home to one of the oldest male Western Lowland Gorillas in the world. This gorilla’s name was Ozzie, and he was born around 1961, making him about 61 years old when he died in 2022. Ozzie fathered 12 gorillas at the Atlanta Zoo and hated loud music, but loved oranges and cabbage.

The Smithsonian National Zoo has six Western Lowland Gorillas. Their names are Baraka, Mandara, Calaya, Kibibi, and Kojo. Baraka is a silverback and the largest member of the gorilla troop who weighs more than 400 pounds. He was born at the zoo in April of 1992.

Mandara raised Baraka as her own offspring shortly after his birth and had six babies of her own. Kojo, one of Mandara’s offspring along with Kibibi, is a young adult male and is one of the most playful gorillas there.