People have harvested the diverse vertebrate community of Central African forests for millennia, depending on wild meat for protein and to improve their livelihoods; however, recently human population growth, more efficient weapons and greater access to forests have yielded unprecedented rates of modern bushmeat hunting. Hunting alters the vertebrate community by selecting against prey species, resulting in some species ‘losing’ (decreasing in abundance) and others ‘winning’ (increasing in abundance). Large-bodied, tropical mammal species with low reproductive rates, such as primates, are particularly sensitive to hunting pressures and are often ‘losers’ in this process. On the other hand, smaller-bodied sympatric species such as rodents are often ‘winners’ and can come to dominate communities with release from predation and competition for resources.
A new study shows that hunting has dramatically reduced wildlife biodiversity in forests near rural villages in Gabon. The colleagues surveyed wildlife populations along 24 straight sampling lines running between 60 small villages in the Ogooue-Ivindo province of northeastern Gabon. Survey sites were located at distances from 2 kilometers to 30 kilometers outside the nearest village. At each survey location, the team documented the diversity and abundance of all large vertebrate animal species they observed, along with any evidence of hunting - such as discarded shotgun shells, campfire sites or sightings of hunters themselves.
We observed a sharp decline in species diversity and a change in species composition the closer we got to any village. Conversely, the richness of mammal species increased by roughly 1.5 species for every 10 kilometers we traveled away from the village. That's a much steeper gradient of change than we had anticipated. It presents new evidence that bushmeat-hunting by rural communities is drastically shaping the wildlife community, an effect that could cascade through entire ecosystems and alter forest composition and diversity across the entire region. And this problem is only going to grow worse as the human population in the region increases.
The concentrated small-scale hunting occurring around the villages likely is also having an impact on plant diversity in the region. As the number of seed-dispersing species such as monkeys and apes decreases with proximity to villages and the number of seed-eating rodents rises, the relative abundance of large fruiting trees, which are food sources for both animal and human populations, could be reduced across the landscape.
The researchers suggest that near villages, resource management should focus on sustainable community-led hunting programs that provide long-term supplies of wild meat to rural people. Resource management far from villages should focus on law enforcement and promoting industry practices that maintain remote tracts of land to preserve ecosystem services like carbon storage and biodiversity.