New survey nearly doubles Grauer’s gorilla population, but threats remain

  • A recent survey led by the Wildlife Conservation Society has revised the population estimate for Grauer’s gorillas to 6,800, up from a 2016 estimate of 3,800.
  • The survey includes data from the Oku community forests in the eastern Democratic Republic of Congo, which could not be surveyed in 2016 due to security issues.
  • Endemic to the eastern DRC, Grauer’s gorillas are still classed as critically endangered, and face threats due to mining and bushmeat hunting.
  • The large numbers of gorillas observed in the community forests surrounding Kahuzi-Biéga National Park underscore the importance of engaging local communities in conservation.

New research indicates that the global population of Grauer’s gorillas may be almost twice as high as previously estimated, leading to renewed optimism among conservationists about the future of the critically endangered ape.

A study led by the Wildlife Conservation Society (WCS) published last month has updated the global population estimate for Grauer’s gorillas (Gorilla beringei graueri) — the world’s biggest gorilla subspecies, found only in the Democratic Republic of Congo — to 6,800 individuals from a 2016 estimate of 3,800 individuals.

WCS officials said the 2016 survey produced such a low estimate because conflict and insecurity prevented researchers from covering the entire range of the Grauer’s gorilla, also known as the eastern lowland gorilla. The latest study included data from the Oku forests.

In the latest survey, researchers found a total of 3,815 Grauer’s gorillas in Kahuzi-Biéga National Park and contiguous Oku community forests, which lie outside protected areas and mining concessions to which traditional communities have access.

These two areas hold almost 60% of the global population. The other 40% is spread out in different parts of the eastern regions of the DRC.

A Grauer’s gorilla (Gorilla beringei graueri) with baby. The largest gorilla subspecies, Grauer’s gorillas can wiegh over 200 kilograms (450 pounds). Image by Andrew Plumptre.

The study’s authors say the findings came as a surprise, but also an encouragement.

The 2016 WCS-led study indicated that the species’ population had fallen by almost 80% since the mid-1990s. However, the new figures suggest the declines have been nowhere near as steep and that the population in the Oku forests and in highland areas of the national park have remained stable over the last two decades.

“I was very surprised at the findings as our message in 2016 was that the situation for the gorillas was pretty catastrophic,” Deo Kujirakwinja, co-author of the study and WCS DRC technical director, told Mongabay. “Now, they are still critically endangered, but we know there are more of them in places we could not look last time. We may even find some more in other areas we have yet to search.”

The figures, while encouraging, do not change the fact that the Grauer’s gorilla remains critically endangered.

Emma Stokes, WCS Central Africa director, told Mongabay that killing for bushmeat remains the biggest threat to the animals, but that mining poses a growing danger.

“The area is very rich in minerals and there has been a loss of habitat through mining and clearing of land. As demand for certain minerals rises, we expect to see an increase in mining,” she said.

More than 50% of the world’s supply of coltan, used in many electronic devices and electric cars, and 80% of global supply of cobalt is found in the DRC, including much of the Grauer’s gorilla habitat.

An infant Grauer’s gorilla in Kahuzi-Biéga National Park. About 60% of the species’ global population lives in the park and surrounding community forests. Image by Joe McKenna via Wikimedia Commons (CC BY 2.0) .

The community forests, where intensive industry like mining is not allowed, could play a crucial part in helping preserve habitat for the Grauer’s gorillas, according to Kujirakwinja, who said the study highlighted “the crucial importance of these forests — and the need to protect them — to the gorillas and their future.”

Indeed, the research suggests the Oku community forests have more Grauer’s gorillas than any other site across its range.

In 2018, three local community forest concessions comprising a total area of 1,465 square kilometres (565 square miles) were created and attributed to community management in Oku.

WCS has been working with these communities on their plans for the forests and “helping them develop the land for use, but in a way that is sustainable for the local habitat,” Kujirakwinja said.

“These community concessions provide safeguards for forests and protect them from landgrabs for developments and mining and other activities,” Stokes said. “It would be lovely to just have land left alone entirely as forests, but that is impossible because these communities live there and need to use that land.”

Other primate experts agree that the engagement of local communities in conservation efforts is crucial in helping the gorillas.

Describing the population upgrade for the Grauer’s gorilla as “really good news,” Alex Georgiev, a primatologist at Bangor University in the U.K. who was not involved in the recent study, told Mongabay: “Community-based conservation, which is becoming more popular, is the only way that conservation will work on a large scale. You cannot just produce national parks everywhere. You have to get the buy-in from local people for any conservation to work properly.”

Grauer’s gorilla. A 2016 survey estimated the species’ global population at just 3,800 individuals, but a more recent survey, covering areas previously off-limits to researchers due to insecurity, revised the estimate up to 6,800. Image by Joe McKenna via Wikimedia Commons (CC BY 2.0).

“In many places, what we are seeing is a greater overlap between areas of human subsistence activity and areas of ape habitat,” he added. “We must learn to be able to have both species co-exist.”

He cautioned, though, that this may not be easy in the DRC, which is troubled by insecurity, political instability, and socioeconomic hardship.

“There is no simple answer to conservation of a species. It is very difficult in some places to establish a conservation programme, and to meet the needs of local people as well as animals. There is a difficult military situation in the DRC, and insecurity is never a help to conservation in any country,” Georgiev said.

Beyond these community forests, the key to the gorillas’ future prospects lies in the creation of a wildlife reserve, according to the study’s authors.

WCS has been working with the government and local NGOs to create a wildlife reserve in the Oku forests to secure up to 3,000 km2 (1,158 mi2) of forest for gorillas and other flora and fauna.

“I am optimistic about the gorillas’ future but with some caveats,” Kujirakwinja said. “The wildlife reserve needs to be established.”

He said he believes the reserve could be established within three years if all goes well.

“For the gorillas to continue to exist they need a lot of space and if you can preserve that habitat, for example in a wildlife reserve, it is going to help them,” Georgiev said. “The buffer of community forests around a reserve sounds like an idea that could work well.”



  • Plumptre, A. J., Kirkby, A., Spira, C., Kivono, J., Mitamba, G., Ngoy, E., … Kujirakwinja, D. (2021). Changes in Grauer’s gorilla (Gorilla beringei graueri) and other primate populations in the Kahuzi‐Biega National Park and Oku Community Reserve, the heart of Grauer’s gorilla global range. American Journal of Primatology. doi:10.1002/ajp.23288

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