Western lowland gorilla

Photograph by Joel Sartore, National Geographic Photo Ark
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A male and female western lowland gorilla photographed at Gladys Porter Zoo in Brownsville, Texas.
Photograph by Joel Sartore, National Geographic Photo Ark

What is the western lowland gorilla?

Western lowland gorillas are the smallest of the four gorilla subspecies, which also include the Cross River gorillas, Grauer’s gorillas, and mountain gorillas. Western lowland gorillas have shorter black-brown hair, longer arms, and a more prominent ridge along their brow. Infants have a tuft of white hair on their backsides, and older gorillas may get streaks of silver in their hair. Like their cousins, western lowland gorillas are endangered and face the loss of their habitat.

Habitat and diet

As the most widespread gorilla subspecies, the western lowland gorilla can be found across more than 270,000 square miles of central and West Africa—including Cameroon, Central African Republic, the Democratic Republic of the Congo, Equatorial Guinea, Gabon, Angola, and the Republic of the Congo. These gorillas live in thick tropical rainforests, where they find plenty of food for their vegetarian diet. They eat roots, shoots, fruit, wild celery, and tree bark and pulp.

Behavior

Gorillas can climb trees, but they’re usually found on the ground in communities—known as troops—of up to 30 individuals. Troops are led by one dominant, older adult male, often called a silverback because of the swath of silver hair that adorns his otherwise dark fur. Troops also include several other young males, some females, and their offspring.

The leader organizes troop activities, such as eating, nesting in leaves, and moving about the group's home range. Though gorillas can stand upright, they prefer traveling on all fours, pushing themselves forward with their knuckles and soles of their feet.

When challenged by another male, a troop leader will demonstrate his strength by standing upright, throwing things, making aggressive charges, and pounding his huge chest while barking out powerful hoots or unleashing a roar. Despite these displays and the animals’ obvious physical power, gorillas are generally calm and nonaggressive unless they are disturbed.

Communication

Though they’re normally quiet animals, western lowland gorillas have an extensive array of vocalizations—at least 22 different hoots, barks, and screams, each with its own meaning. In captivity, gorillas have displayed significant intelligence and have even learned simple human sign language.

Reproduction

Female gorillas give birth to one infant after a pregnancy of nearly nine months. Unlike their powerful parents, newborns are tiny—weighing about four pounds—and are capable of doing no more than clinging to their mothers' fur. These infants ride on their mothers’ backs from the age of four months through the first two or three years of their lives. Young gorillas, from three to six years old, spend much of their day at play, climbing trees, chasing one another, and swinging from branches.

Threats to survival

While western lowland gorillas are one of the more populous gorilla subspecies, they face a number of threats that have led the International Union for Conservation of Nature (IUCN) to classify them as critically endangered.

Forest loss is a twofold threat: It destroys gorilla habitat, and it clears the way for people who hunt gorillas for bushmeat. Nearly 80 percent of western lowland gorillas live in unprotected areas that are vulnerable to poaching.

Farming, grazing, and expanding human settlements are shrinking the western lowland gorilla's space. Climate change further threatens their habitat as warming temperatures dry out the region, making it more vulnerable to fire and forest retreat.

Gorilla populations have also been ravaged by infectious diseases. Experts believe that the Ebola virus may have killed as much as a third of western lowland gorillas in the early 2000s.

Conservation

Though western lowland gorillas are protected by national and international laws, historically enforcement has been weak. Conservation groups aim to change that by working with local and national authorities to strengthen penalties for poaching and improve land-use planning to better protect the gorilla’s habitat.

In 2018, researchers surveying the gorilla’s range made an uplifting announcement: Their study found 361,900 western lowland gorillas—a third more than previously had been estimated. As Liz Williamson, great apes coordinator for the IUCN told the Guardian at the time, “Our study has revealed that it is not too late to secure a future for gorillas.”