African great apes will lose most of their range in the next 30 years

African great apes will suffer massive range losses over the next 30 years, according to a new report from the Wildlife Conservation Society. Gorillas, chimpanzees and bonobos are being pushed out of their historical range as a result of human population growth, land use changes, and the impacts of climate change.

“There must be global responsibility for stopping the decline of great apes,” said study senior author Hjalmar Kuehl. “Global consumption of natural resources extracted from ape range countries is a major driver of great ape decline. All nations benefiting from these resources have a responsibility to ensure a better future for great apes, their habitats and the people living therein by developing more sustainable economies.”

The experts analyzed data on African great apes from the IUCN, using a database that contains two decades of information on population status and conservation for several hundred sites.

The researchers projected the combined effects of climate change, land use changes, and human population growth through 2050 based on a best- and worst-case scenario.

Even under the “best-case scenario,” the authors predict that great apes will lose 85 percent of their range, half of which will fall outside of national parks and other protected areas. Under the worst-case scenario, the apes will lose 94 percent of their range.

“By integrating future climate and land-use changes as well as human population scenarios, this study provides strong evidence for synergistic interactions among key global drivers constraining African ape distribution,” said lead author Joana Carvalho.

“Importantly, massive range loss is widely expected outside protected areas, which reflects the insufficiency of the current network of protected areas in Africa to preserve suitable habitats for great apes and effectively connect great ape populations.”

Climate change will make the mountain areas more suitable than the lowlands for African great apes. If they are able to physically move from the lowlands to the mountains, they may be able to survive, and even increase their range – depending on the species. However, the researchers noted that the apes may not be able to relocate in the time remaining between today and 2050.

“As climate change forces the different types of vegetation to essentially shift uphill, it means that all animals – not only great apes – that depend on particular habitat types will be forced to move uphill along with the vegetation, or become locally extinct,” said study co-author Fiona Maisels.

“And when the hills are low, many species, great and small, will not be able go higher than the land allows, and huge numbers of animals and plants will simply vanish.”

The study authors argue that effective conservation strategies require careful planning for each species that focuses on both existing and proposed protected areas – the creation and management of which can be informed by these habitat suitability models. In addition, efforts to maintain connectivity between suitable habitats will be crucial for the survival of African great apes. 

The study is published in the journal Diversity and Distributions.

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By Chrissy Sexton, Earth.com Staff Writer