8.3.4.3: Gorillas

The Gentle Giants

If you've ever had the chance to observe gorillas at a zoo, you probably couldn't help but feel struck by their sheer size, their human-like gestures, and their surprisingly gentle nature. They are truly magnificent animals. In fact, gorillas are so calm and approachable, even in the wild, that people pay up to thousands of dollars for guided gorilla treks in central Africa just for the chance to spend anywhere from an hour to half a day in their presence.

That gentle quality has captivated researchers and filmmakers for decades. In a recent Netflix documentary, “A Gorilla Story,” Sir David Attenborough returns to the forests of Rwanda to track down the descendants of a male gorilla, named Pablo, that he first met in the 1970s while filming “Life on Earth” for the BBC. Pablo grew up to become a dominant silverback whose family would come to lead the largest mountain gorilla group ever recorded. The documentary offers a rare multigenerational glimpse into gorilla life and serves as both a celebration of these animals and a sobering reminder of how much their world has changed.

The Dian Fossey Gorilla Fund and the Power of Long Term Research

The recovery of mountain gorillas didn't happen by accident. It is the result of decades of patient, rigorous scientific work, much of it carried out by the Dian Fossey Gorilla Fund. Founded in 1967 by pioneering primatologist Dian Fossey, the organization is now the world's largest and longest-running dedicated to gorilla conservation.

Recently, the Fossey Fund served as scientific advisors on the Netflix documentary A Gorilla Story: Told by David Attenborough, providing field expertise and behavioral interpretation drawn from nearly six decades of continuous research. The film follows the remarkable history of the Pablo family of mountain gorillas, a group followed across generations since Fossey's time. Without that deep scientific foundation, the filmmakers could not have told the full and intimate story of a real-life gorilla dynasty.

This is a powerful example of why long-term scientific research matters. Individual studies capture snapshots; decades of continuous observation reveal a richer, fuller picture — births, deaths, power struggles, family bonds, and the slow changes that shape a population over time. The mountain gorillas represent one of conservation’s rare success stories. Once pushed toward extinction, they are now the only great ape species whose population is increasing — a recovery made possible through a sustained commitment to research and collaboration with local communities.

Netflix (2026, March 23). A Gorilla Story: Told by David Attenborough |Official Trailer |Netflix. [Video]. YouTube. https://youtu.be/u6Qs4W0uwBw?si=DoL8FtQMSlUH3lRZ

About The Dian Fossey Gorilla Fund

Established in 1967 by famed primatologist Dian Fossey, the Fossey Fund works in Rwanda and the Democratic Republic of the Congo to protect and study critically endangered wild gorillas and their habitats, and to support the people who share the gorillas’ forest home. For more information, visit: gorillafund.org. Follow them on social @savinggorillas.

Size, Social Life, and Structure

Gorillas are the largest of all apes and live exclusively in Africa. They live in social groups called troops, typically made up of 10 to 20 individuals—one dominant silverback male, several adult females, and their offspring. The silverback gets his name from the distinctive patch of silvery hair that develops on his back and rump as he matures. He is the sole breeding male in the group, and his role goes beyond reproduction: he protects the troop, mediates conflicts, and plays an active role in socializing the younger members. This mating arrangement—one male with multiple females—is known as polygyny, a pattern seen in some human societies as well.

The size difference between males and females is striking. Males can weigh up to 350-400 pounds, while females typically weigh closer to 155-200 pounds, making gorillas one of the most sexually dimorphic of the great apes.

Daily Life

Gorillas are primarily herbivores, feeding mainly on leaves, stems, and fruit, occasionally supplemented with ants and other insects. Given the relatively low caloric density of leaves, gorillas spend a large portion of their waking hours eating as it takes a lot of foliage to fuel a 350-pound ape.

They move through their environment by knuckle-walking, supporting their weight on the knuckles of their hands rather than their palms. While they are capable climbers, gorillas are mostly terrestrial and construct sleeping nests on the ground whenever they want to rest or sleep, weaving together nearby leaves, vines, and branches into a comfortable bed. With the exception of young infants, who sleep with their mothers, each gorilla in the troop builds its own nest. And since gorillas follow food availability and are frequently on the move, they rarely sleep in the same spot twice.

Because gorillas can be elusive and shy around humans, field scientists often rely on nest counts to estimate the size and movements of a troop. Each nest represents one individual, making them a surprisingly useful census tool.

Gorilla infants are born helpless and require intensive care from their mothers, nursing at least once an hour in the early weeks of life. Silverbacks also invest in the young of the group—protecting infants from threats and playing an important role in socializing juveniles. In the wild, gorillas typically live between 35 and 40 years.

Two Species, Both in Trouble

Gorillas are divided into two species: the western gorilla and the eastern gorilla. All populations are critically endangered, meaning they are one step away from extinction. Perhaps the most well-known are the mountain gorillas (Gorilla beringei beringei), a subspecies of eastern gorilla living in the highland forests of the Democratic Republic of Congo, Rwanda, and Uganda near the Virunga volcanoes. With under 1,000 individuals remaining, their situation is precarious. Threats include poaching, habitat loss due to human expansion, and the destabilizing effects of ongoing political unrest in the region, making conservation work both urgent and dangerous.

As discussed in the section above, there is a rare conservation success story here. Mountain gorilla numbers hit an all-time low of just 254 individuals in the 1980s, but sustained conservation efforts have slowly pushed that number back up. They are one of the few great apes whose population is actually growing.

Notably, there are no mountain gorillas in captivity, and this is unlikely to change. Mountain gorillas are highly sensitive to human diseases, including common respiratory illnesses like the cold and flu, to which they have little natural immunity. In captivity, the risk of disease transmission from humans is extremely difficult to control. Mountain gorillas are also deeply tied to their high-altitude forest habitat, which is difficult to replicate in a zoo setting. They have a highly specialized diet of specific plants that grow in those forests, and the psychological stress of captivity itself has proven fatal. Previous attempts to keep mountain gorillas in captivity have resulted in the animals' deaths, and conservationists have concluded that their survival depends entirely on protecting them in the wild.

The picture is darker for the eastern lowland gorilla, whose population has declined by roughly 70% over the last two decades — a staggering loss driven by habitat destruction, instability in the region, and a threat that has grown more calculated and demand-driven over time: the illegal wildlife trade. As discussed in Chapter 7, the trade in baby great apes has evolved into a deliberate, order-driven business fueled in part by social media. Every infant taken represents not just one lost animal, but the loss of a future mother or silverback, and for a species already in steep decline, those losses compound quickly.

For gorillas, as for all great apes, the threats are interconnected. Forests are cleared, instability follows, hunters move in, and traffickers are not far behind. Understanding these pressures together, rather than in isolation, is essential for understanding why great ape populations are in crisis, and what it will take to turn the tide.