In Cameroon’s forgotten forests, gorillas and chimps hang on

At first glance, it’s easy to dismiss the ecological significance of Mbalmayo Forest Reserve in southern Cameroon, one of several degraded forest patches scattered across the country. Located on the outskirts of the town of Mbalmayo, about 50 kilometers (30 miles) from the country’s capital, Yaoundé, the reserve appears to be too close to human habitation to harbor a wealth of biodiversity — or at least that’s what scientists thought.

But when wildlife conservationist Jean Christian Mey Boudoug visited Mbalmayo to pursue fieldwork for his Ph.D. in the late 2010s, he was surprised to see parts of the forest still intact and flourishing. Although his research showed the reserve had lost nearly 30% of its forests to banana and cacao plantations by 2018, when he looked closer, he discovered what many trained eyes had missed.

“We found some evidence of what seemed to be chimps or gorilla,” Boudoug told Mongabay, referring to nests he found in the forest. Since the 1960s, just one primate species, the northern talapoin (Miopithecus ogouensis), was known to inhabit Mbalmayo Forest Reserve. Other species found in the area include duikers (Cephalophus spp.), African civets (Civettictis civetta), African palm civets (Nandinia binotata) and other small mammals. There were no photos or videos of other primates.

So Boudoug bought a few trail cameras off the internet with his own money and installed them in the reserve. When community members living around Zamakoe Forest Reserve, another similarly degraded forest patch just north of Mbalmayo, told him about chimpanzee calls they’d heard in their backyards, he extended his network of camera traps to include that reserve.

During the wet and dry seasons of 2021 and 2022, Boudoug and his colleagues installed 12 trail cameras that continuously recorded signs of animal movements in the two forest reserves. When Boudoug analyzed the videos a year later, he was stunned to see that the cameras had recorded a critically endangered western lowland gorilla (Gorilla gorilla gorilla) and several central chimpanzees (Pan troglodytes troglodytes), presenting the first evidence of great apes in the reserves. The researchers reported their findings in a study published in the African Journal of Ecology.

Cameras traps captured a group of chimpanzees just 150 m away from human habitation. Video courtesy of Christian Mey Boudoug.

The gorilla was caught passing through an intact patch of limbali (Gilbertiodendron dewevrei) trees in Mbalmayo, suggesting the remnant forests provide a habitat suitable for great apes. In October 2022, the researchers also saw a gorilla nest in a swamp there.

The chimpanzees were caught on video 12 times over the two years, foraging on fruit trees in the two reserves during both the wet and dry seasons, suggesting they regularly use the forests to access food or as a corridor to move between forests. They were often seen in groups with adults, infants, subadults and juveniles, although the latter two were seen more often on video than the others.

The most alarming finding of the study was the discovery of two videos of apes and humans using the same part of the forest, just a few hours apart, highlighting potential risks of human-ape conflict.

“At three to sometimes eight hours of difference, we have overlapping of the use of the area by both the chimpanzees and women or men coming to collect [fruits and other forest produce],” Boudoug said. “What if those people had come to harvest there three hours earlier? There would have been a clear clash between chimps trying to feed, and a man, his wife and a dog.”

While apes are known to adapt to human presence, ape-human conflicts put these already threatened animals in harm’s way. Although chimpanzees and gorillas enjoy the highest levels of protection in Cameroon, they’re often killed for their meat or body parts, shot at for raiding farms or for fear of personal safety, or become victims of trafficking.

Need for conservation beyond protected areas

The Mbalmayo and Zamakoe forest reserves don’t have high-value timber, so aren’t as heavily logged as other reserves in Cameroon.However, communities living around these forests collect fruits and other nontimber forest products from them. These reserves aren’t prized for their biodiversity either, so the Cameroonian government doesn’t afford them the same levels of protection or support it gives to national parks.

“Non-protected areas are kind of forsaken,” Boudoug said, adding that although these reserves don’t have intact forests or foster high levels of biodiversity, they do provide some of the last refuges for great apes, and that can’t be ignored.

“The areas where the chimpanzees have been discovered are riparian forest, which are hard to exploit [for agriculture],” Boudoug said, “They remain the last bastion where chimpanzees are free to move inside those areas.”

The fact that the two highly fragmented areas, with significant human presence, are home to around 20 chimpanzees, as seen in the videos, highlights the need to protect these reserves, he said.

The presence of great apes in Cameroon’s degraded forests isn’t limited to the two forest reserves.

“We have apes in so many forest patches in Cameroon,” said wildlife biologist Angwa Gwendoline, founder of Action for Conservation and Environmental Sustainability (ACES), a grassroots NGO in Cameroon, who wasn’t involved in the study. “If you go to the Deng Deng National Park [in eastern Cameroon], where we have a huge population of gorillas and chimpanzees, you’ll see that half of the population of great apes are moving out of the protected area into community forests and farmlands.”

In 2020, the Cameroonian government launched a project to establish a conservation corridor for great apes that connects some of the isolated populations in fragmented landscapes in the country. Gwendoline, who was a part of the project, said that while it identified some forest patches where great apes were known to occur, it didn’t include the Mbalmayo and Zamakoe forest reserves. The new evidence will help change that, she said.

“The study is really very significant, considering the status of apes,” Gwendoline said. “It gives room for further research to be done and for us to advocate for good policies and better ways to conserve these places.”

Banner image: A western lowland gorilla in Cameroon. Gorillas, which are critically endangered, are at risk of coming in close contact with humans in degraded habitats. Image by Nikolas AUBOURG via iNaturalist (CC BY-NC 4.0).

Study highlights elusive Cameroonian gorillas, and the threats encircling them

Citations:

Mey, C. B., & Gore, M. L. (2021). Biodiversity conservation and carbon sequestration in agroforestry systems of the Mbalmayo Forest Reserve. Journal of Forest and Environmental Science, 37(2), 91-103. doi:10.7747/JFES.2021.37.2.91

Mey Boudoug, J. C., Dewang Dyio, S., Fotie, C. N. S., Etah Kang, J., Ndzana, I., Nguimdo Vouffo, V. R., & Mbolo, M. M. (2025). Preliminary evidence of great apes’ occurrence in peri‐urban and highly degraded forest reserves in Cameroon. African Journal of Ecology, 63(2). doi:10.1111/aje.70022

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