The Western Lowland Gorilla Is Susceptible to Ebola

By: Nicole Antonio & Sascha Bos  | 
Black gorilla with silverback fur walks through short grass on all fours
This male western lowland gorilla, 32 years, sports silver coloring on his back as he walks along the edge of the forest at Dzanga Sangha Special Dense Forest Reserve. Younger gorillas don't typically have this silverback color. Anup Shah / Getty Images

The western lowland gorilla (Gorilla gorilla gorilla) is fortunate enough to boast the highest population numbers of all gorilla subspecies, but they are still considered endangered. They can be found in various countries in Western Africa, including Cameroon, the Central African Republic, the Democratic Republic of the Congo, Equatorial Guinea, Gabon, Angola and the Republic of the Congo.

These gorillas inhabit dense rainforests, swamps and lowland forests, making their exact population size difficult to determine due to the remote and inaccessible nature of the western lowland gorilla's habitat.

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Gorilla Taxonomy

The western lowland gorilla is one of two subspecies of western gorillas. Cross river gorillas (Gorilla gorilla diehli) are the other subspecies of western gorillas and are much rarer than western lowland gorillas, numbering a few hundred individuals compared to the western lowland gorilla's population of several hundred thousand.

In 2001, eastern gorillas (Gorilla beringei) were recognized as a separate species, also with two subspecies: Grauer’s gorillas (Gorilla beringei graueri) and mountain gorillas (Gorilla beringei beringei).

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Physical Characteristics of Western Lowland Gorillas

How can you distinguish western lowland gorillas from other gorilla subspecies? They're slightly smaller than their cousins, but you might not catch that unless you've arranged a side-by-side comparison. (They're actually the smallest of the four gorilla subspecies.) Western lowland gorillas also have brownish-gray hair, lighter chests, wider skulls with pronounced brow ridges and smaller ears.

Adult male gorillas, known as silverbacks, can reach a height of 4.5 to 5.5 feet (1.4 to 1.75 meters) and weigh between 300 and 600 pounds (136 to 272 kilograms). Adult female western lowland gorillas typically weigh between 150 to 300 pounds (113 to 136 kilograms).

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The silverbacks have (as you might expect) silvery-gray fur on parts of their body — specifically their backs and upper legs — which becomes more prominent as they mature.

A pronounced brow ridge and a broad, flat nose are easily spotted characteristics of this species. You may also notice that they have flat ears and particularly sharp canines, which come in handy for both eating and self-defense. They possess 32 teeth in all.

Their legs are actually shorter than their arms, creating a poster that allows gorillas to "knuckle-walk," meaning they walk on all fours. Gorillas have opposable thumbs and toes, enabling them to climb, grasp objects and manipulate their environment.

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Western Lowland Gorilla Habitat and Range

Western lowland gorillas inhabit a wide range of habitats within the Congo Basin, including rainforests, swamps and lowland forests. They have been recorded in areas up to 8,000 feet (2.4 kilometers) above sea level.

These gorillas are distributed across more than 270,000 square miles (699,297 square kilometers) of Western and Central Africa, including Angola, Gabon, Cameroon, the Central African Republic, the Democratic Republic of Congo, Equatorial Guinea and the Republic of Congo.

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The dense rainforests and swamps provide an abundant food source for western lowland gorillas. They primarily feed on fruit, roots, leaves, bark, roots, pith and wild celery. Water is primarily obtained through the consumption of vegetation.

Troops and Social Organization

Western lowland gorillas live in groups called troops, which can range in size from as little as a single pair to 30-plus members. However, the average troop size is around five individuals.

A typical troop, led by a dominant silverback male, often consists of at least one other black back male in addition to several adult females — and, of course their offspring. The composition of the group can vary due to a number of factors, including immigration/emigration patterns, as well as births and deaths within the troop.

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Mature offspring, both males and females, usually depart form the group they were born within to find mates. Females emigrate into new groups at around eight years old, choosing the silverback based on factors such as size and home habitat.

A female gorilla may change family groups multiple times throughout her life. Some sexually mature males may attempt to replace the silverback in an established group, but they often spend a few years as bachelor males. Troops can also be formed when non-related females join a lone male.

The dominant silverback male leads the group, regulating their activities such as feeding, nesting and movement within their home range. He also has what you might call the "right of first refusal" when it comes to breeding, although sub-adult males may have opportunities to mate with females as well, depending on the group.

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Threats to Western Lowland Gorillas

Despite being the most numerous gorilla subspecies, western lowland gorillas face significant threats, leading to their classification as critically endangered on the IUCN Red List. The primary threats to their survival are poaching and disease.

Poaching

Poaching poses a severe threat to western lowland gorillas. Although the hunting and killing of gorillas are illegal, they are still targeted for bushmeat or captured as pets.

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In some regions, approximately 5 percent of western lowland gorillas are killed each year. The opening of once remote forests by timber and other companies has facilitated poaching and the bushmeat trade.

Poaching also carries risks for humans, as the butchering and handling of gorilla and other primate meat may contribute to the spread of diseases such as Ebola.

Disease

Western lowland gorillas are susceptible to infectious diseases, including the deadly Ebola virus. Outbreaks of Ebola have caused significant die-offs among western lowland gorilla populations, with estimates suggesting that it has killed up to one-third of the wild gorilla population.

The toll has been even higher in certain areas, such as the Minkébé Forest, where the virus may have decimated more than 90 percent of the gorilla and chimpanzee populations.

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Conservation Efforts and What You Can Do to Help

Conservation organizations, such as the World Wildlife Fund (WWF), are working to protect western lowland gorillas and their habitat. Efforts focus on establishing protected areas across the Congo Basin and promoting sustainable development practices in logging and mining industries.

These initiatives aim to conserve the gorillas' habitat, reduce poaching, and mitigate the spread of diseases. Even as just one person, there are several ways you can contribute to the conservation of western lowland gorillas.

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  • Raise awareness: Share information about the threats facing western lowland gorillas and the importance of their conservation with friends, family and colleagues.
  • Support conservation organizations: Donate to reputable organizations working to protect gorillas and their habitats.
  • Choose sustainable products: Purchase products that are certified as sustainable, such as timber and palm oil, to reduce habitat destruction.
  • Avoid wildlife products: Refrain from purchasing products made from gorilla or other endangered animal parts, as this contributes to the illegal wildlife trade.
  • Engage in responsible tourism: If visiting areas where western lowland gorillas are found, choose responsible tour operators that prioritize the well-being and conservation of the gorillas. Follow guidelines to minimize disturbance to the animals and their habitat.

By taking these actions, we can contribute to the preservation of the critically endangered western lowland gorilla population and ensure a future for these magnificent creatures in the wild.

This article was created in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.

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