The human footprint of overhunting in Cameroon's forests

Environment | Forests

By Sophie Coxon, Kingfisher Writer

Published October 14th, 2022

In the Dja Biosphere Reserve of Cameroon, human activity on the diversity and abundance of local native mammal species have had a significant impact. Targeted hunting of certain-sized mammals has reduced the area’s species richness, with smaller mammals dominating and upsetting the natural balance.

Rich, green hills of thick rainforest stretch to the horizon in every direction, while heavy clouds fringe the canopy in a blanket of humid mystery. In the distance, a troupe of mangabeys can be heard howling from the treetops, amongst the orchids and vines, where sunbirds flit between nectar blossoms and white-crested hornbills perch. The dense rainforest of Cameroon is a complex web of wildlife, but it is not invincible to human touch.

A pangolin, the most illegally trafficked animal in the world. | Louis Mornaud / Unsplash

Understanding the relationship between humans and local wildlife in fragile areas is an extremely important part of conservation research. Human impacts threaten many species worldwide, and the effect of anthropogenic activity is widely understudied across the globe.

In the tropics, rural communities often depend on bushmeat for a protein source and to sustain their families and livelihoods, however, there is a lack of knowledge about how sustainable these practices are.

African tropical rainforests harbour a diverse array of endangered and threatened species. They are also home to many rural forest communities, making this biome a key area to collect baseline data on human-mammal interactions. In the Dja Biosphere Reserve of Cameroon, the effects of human activity on mammal species distribution and composition were investigated in a study led by the University of Cambridge.

‘The dense rainforest of Cameroon is a complex web of wildlife, but it is not invincible to human touch.’

A biosphere reserve is a defined site dedicated to testing and observing different environmental management approaches. Typically, a biosphere reserve includes a protected central study area called the core, where the majority of research takes place, surrounded by a buffer zone, and then a transition zone. The buffer and transition zones include human settlements, education facilities, and ecotourism developments.

The Dja Biosphere reserve lies in the south of Cameroon, spanning approximately 800,000 hectares mainly of flat, dense, and largely intact rainforest. The reserve also contains 37 villages and 44,000 inhabitants, with 4,000 living in the core study zone. The reserve also provides a vital habitat for endangered mammals such as chimpanzees, leopards and giant pangolins.

The demand for bushmeat is increasing due to rapid urbanisation and population growth, along with the rising price of farmed meat, particularly in the past three decades.

The three major zones of a biosphere reserve and their general uses; the core study zone is used primarily for scientific research and is a rich habitat for wildlife with minimal human land use, the transition zone includes a combination of natural wildlife habitats and human agricultural lands, used for settlement, education, and tourism, and the outer buffer zone is the most heavily used by humans, with a higher occurrence of settlements, tourism developments, and education centres.| Sophie Coxon / The Kingfisher

New roads and the advancement of weapons have also made bushmeat more accessible to hunters, leading to localised pockets of overhuntingㅡcommon African bushmeat species have declined by an estimated 60% since 1970. This unsustainable practice upsets the natural balance of fauna within the ecosystem, meaning certain functions and roles are lost or not sufficiently fulfilled.

In the African rainforest, large ungulates and primates are important in natural seed dispersal and are also the primary target of bushmeat hunting. When populations are overexploited, the rate of seed dispersal for many fruiting trees decreases, limiting the distance the varying tree species can spread, which ultimately leads to a less biodiverse forest structure.

‘When populations are overexploited, the rate of seed dispersal for many fruiting trees decreases … and ultimately biodiversity.’

Hunters selectively target the larger, heavier animals as these provide a greater reward in terms of food or money, for hunting effortㅡenvironments which are dominated by small ungulates and rodent species can hence be indicative of unsustainable hunting practices.

As roads are often conduits for hunter access and imply greater human disturbance, they can also be used as an indicator of human impact. Species richness often increases with distance from roads, suggesting that animals are disturbed by road activity and/or hunting is concentrated in areas closer to roads, as they are more accessible.

Between August and September of 2017, a camera-trap survey captured a total of 24 different mammal species in the reserve, and occupancy analysis was carried out to estimate the area of the reserve used by each species. The number of species recorded plateaued after 80 days and hence it was concluded that all species in the area possible to record had been captured.

The most commonly recorded species were duikers, mangabeys and porcupines, all of which have a small body mass and suggest overexploitation of the broader biosphere reserve. Larger mammals such as forest elephants, large felids and giant pangolins were not detected despite predictions of their presence, another sign that unsustainable hunting practices may have depleted the area of large mammals.

‘The most commonly recorded species were duikers, mangabeys and porcupines, all of which have small body mass and suggest overexploitation of the broader biosphere reserve.’

In the zones closest to settlements, only mammals with low body size, generalist diets and very high reproductive rates were observed, further suggesting that a level of ecosystem degradation is apparent and that the natural faunal balance has been disturbed.

Despite this, both gorillas and chimpanzees were captured on camera within the reserve, in the central zone, showing that it is still an important habitat for these species and they have not been completely eradicated. Promisingly, chimpanzees were found in a relatively even distribution across the study area, suggesting that this species is less impacted by hunting and road disturbances.

The Baka people residing in Dja Biosphere Reserve rely on traditional hunting methods. | Earwig / Wikimedia Commons

Some larger species were detected in the most remote areas far from settlements, which proves that the community forest is not completely devoid of its prior fauna, validating results from other studies in the area.

However, the overall results suggest that human settlements and roads have a large impact on both distributions and the richness of mammal species in the Dja Biosphere Reserve. This highlights the need for more research into the interrelationships of local communities and native wildlife, in order to develop improved management strategies for increasingly successful conservation.

Medium to small-sized duikers showed a positive relationship with proximity to settlements, likely due to an increase in feeding resources and croplands in these areas, as well as reduced competition due to the overhunting of the larger ungulates. This highlights the altered species structure within the reserve, and the need for better management to restore the ecosystem to a more balanced and evenly diverse area.

‘Promisingly, chimpanzees were found in a relatively even distribution across the study area.’

These findings are, however, only the result of a single short-term survey, and hence do not provide conclusions on what has shaped the mammal species structure in Cameroon’s Dja Forest.

However, it does provide insight into the potential and probable effects of human activity on local mammal species. It may instigate increased monitoring of mammal species in the area, and in similar zones across Africa.

Continuous monitoring and survey data are required to form a solid understanding of the intricacies of human-wildlife interactions, and once a more informed knowledge of the area is achieved, more effective management can be put in place to help both communities and wildlife thrive in the beautiful rainforest of the Dja Biosphere Reserve they call home.

However, bushmeat is a traditional part of many communities’ diets, providing a vital protein source and food security to local people, whilst also being culturally significant. Changing conventional hunting methods and habits is no simple task; there are complex aspects which must be addressed to improve the ecological situation, without compromising human values or nutrition.

A grey duiker, commonly seen around the edge of villages, is too small to be worth hunting, so it is relatively undisturbed by human settlements. | Hans Veth / Unsplash

Replacing bushmeat with farmed meat is difficult in rainforest environments, as suitable pasture is rare without felling and burning large areas of forest. Helping raise awareness within the local communities about more sustainable food sourcing will play a large part in the future of biosphere reserves and the management of community forests.

However, it must be noted that overreliance on bushmeat is not the sole cause of mammal, and hence biodiversity decline in the Dja forestㅡit is a multifactorial issue with many complexities. Poaching is a major problem across Africa, and the Dja Biosphere Reserve is in no way immune to this threat, with poachers now using GPS software to aid their hunts and increase poaching success.

The reserve’s anti-poaching programmes are underfunded, making it difficult to predict future mammal population structures and patterns, as animals are at constant risk.

A rubber plantation under Sudcam has also been developed less than 500 kilometres from the western border of the reserve, resulting in extensive deforestation and displacement of local communities. Nearby mining operations and dam construction are exacerbating this problem.

‘Poaching is a major problem across Africa, and the Dja Biosphere Reserve is in no way immune to this threat.’

Through working with local people and promoting increased education about the dynamics of mammal population structures in biosphere reserves, human impact on mammalian species can be lessened; hunting can be spread among a diverse size range of animals, and increased reliance on vegetarian protein sources such as legumes, nuts and seeds can reduce pressure on bushmeat hunting and livestock agriculture.

Despite these steps in the right direction, the Dja Biosphere Reserve and many other tropical forest habitats are under a multitude of threats; to combat the degradation of these magnificent ecological wonderlands, all threats to the forest and its animal inhabitants must be addressed in a holistic conservation approach, if the richness and ecological productivity of the reserve is to be sustained.

Featured Image: ©John Novis | courtesy of Greenpeace

Brashares, J., Arcese, P., Sam, M., Coppolillo, P., Sinclair, A. and Balmford, A. (2004) Bushmeat Hunting, Wildlife Declines, and Fish Supply in West Africa. Science. Volume 306, Issue 5699, pages 1180-1183.

Greenpeace Africa (2016) ‘UNESCO fails to protect Cameroon’s Dja Reserve from multiple threats including the Sudcam rubber plantation’. Greenpeace. Available at: [Accessed September 24th, 2022]

Ini E. (2018) ‘Sudcam: bleeding the forest and its dependent communities’. Greenpeace. Available at: [Accessed September 24th, 2022]

International Union for Conservation of Nature and UN Environment World Conservation Monitoring Centre (1987) ‘Dja Faunal Reserve’. World Heritage Datasheets. Available at: [Accessed September 24th, 2022]

Mackenzie, J. (2022) ‘Global food-price surge led by increase in cost of meat and vegetables,’ Independent. Available at: [Accessed 27 September 2022]

Natural World Heritage Site (2014) ‘Dja Faunal Reserve’. Natural World Heritage Site. Available at: [Accessed September 24th, 2022]

Sackey, H., McNamara, J., Milner-Gulland, E., & Ntiamoa-Baidu, Y. (2022). The bushmeat trade in northern Ghana: Market dynamics, drivers of trade and implications for conservation. Oryx. Volume 56, Issue 5, pages 1-12.

Rosin C., Poulsen J.R. (2016) Hunting-induced defaunation drives increased seed predation and decreased seedling establishment of commercially important tree species in an Afrotropical forest, Forest Ecology and Management. Volume 382, Pages 206-213.

Topa G., Karsenty A., Megevand C., Debroux L. (2009) ‘The Rainforests of Cameroon: Experience and Evidence from a Decade of Reform’. World Bank. Available at: [Accessed September 24th, 2022]

Tudge S., Brittain S., Kentatchime F., et al. (2022) The impacts of human activity on mammals in a community forest near the Dja Biosphere Reserve in Cameroon. Oryx. FirstView article, pages 1-9.

UNESCO (2022) ‘Dja Biosphere Reserve, Cameroon.’ UNESCO. Available at: [Accessed September 11th, 2022]

UNESCO (2022) ’What are Biosphere Reserves?’ UNESCO. Available at: [Accessed September 11th, 2022]

Zoological Society London (n.d.) ‘ Dja Conservation Complex’. ZSL Africa. Available at: [Accessed September 24th, 2022]

Bring back the super-spreaders: How reintroducing howler monkeys can pave the way for seed dispersal

Environment | Forests

Unspoken victims of warfare: the destructive impacts of armed conflict on local biodiversity

Environment | Forests