Human beings are not the only great ape species likely to be severely impacted by climate change in the future. According to a new study by the Drexel University, Wildlife Conservation Society, and other groups, the Nigerian-Cameroon chimpanzee—the most endangered of all chimpanzee subspecies—may lose much of its habitat within the next five years and fully half of it in the next century.
Scientists predict that much of the current habitat of the Nigerian-Cameroon chimpanzee will become degraded by 2020, resulting in significant harm to populations of this rare great ape already threatened by illegal hunting, logging, and other pressures. This is the first study to examine the effects of climate change on the subspecies.
The study appears in the latest issue of the journal BMC Evolutionary Biology.
“The Nigeria-Cameroon chimpanzee is perhaps the least studied of all chimpanzee subspecies. This is the first time that their distribution and habitat has been studied in such detail, and the data used to predict how their habitats might alter under climate change,” said first author Paul Sesink Clee, Graduate Research Fellow at Drexel University. “We were surprised to see that the Nigeria-Cameroon chimpanzees living in the savanna-woodland habitat of central Cameroon are under the most immediate threat of climate change and may completely lose their habitat within our lifetime.”
“Teasing out the differences between different geographical areas for one of our least-studied apes—the Nigeria-Cameroon chimpanzee—has shown that over half of the population could be very severely affected by almost complete loss of their habitat—caused by climate change—in the next seventy years or so,” said Dr. Fiona Maisels, WCS conservation scientist and a co-author on the study. “This is yet another climate change warning to the international community,”
Numbering between 3,500 – 9,000 individuals across their range, the Nigerian-Cameroon chimpanzee is considered to be the least studied subspecies of common chimpanzee as well as the most threatened. The research team collected data from hair and fecal samples for genetic analyses, and other sources such as nesting sites and tools. What emerged was a detailed distribution of two distinct populations of Nigerian-Cameroon chimpanzee. The population in western Cameroon lives in mountainous rainforest, whereas the other population inhabits a mosaic of forest-woodland-savanna (known as ecotone habitat).
The team then combined the population data with the environmental characteristics of their locations (i.e. climate, slope, vegetation, tree cover) to determine how habitat drives the distribution of the Nigeria-Cameroon Chimpanzee. Using climate change scenarios provided by the UN’s Intergovernmental Panel on Climate Change, the team then predicted how habitats might change by the years 2020, 2050, and 2080 under the influence of climate change.
The authors predicted that the mountainous rainforest habitat would fare best in future scenarios, while the mosaic habitat would decline by the year 2020 and could vanish altogether by the year 2080. About half of the Nigerian-Cameroon chimpanzee population would be severely impacted in this worst case scenario. The authors cautioned that their analyses did not include the potential for chimpanzee populations to adapt to these changes.
The team also published a paper on how natural selection and environmental variation play a role in shaping the genetic diversity of chimpanzee populations in the same issue of BMC Evolutionary Biology.
WCS works to study and protect both populations of Nigerian-Cameroon chimpanzee. The largest population of Nigeria-Cameroon chimps is located in the Mbam Djerem Landscape, a region containing the Mbam Djerem National Park and a number of timber concessions. The park is managed by the Cameroonian Ministry of Forestry with strong technical and financial support from WCS and from FEDEC, a Cameroonian foundation. Wildlife populations, including chimps, have remained stable in Mbam Djerem since the creation of the park and the inauguration of assistance from WCS and FEDEC, but this study highlights the global conservation importance of continued effective management in this extraordinary ecotone habitat.
The second largest population is found in the forests and ecotone habitat on the border between Cameroon and Nigeria, in and around Cross River NP (Nigeria) and Takamanda NP (Cameroon). Here too, WCS is the main technical assistance provider to the governments of Cameroon and Nigeria. But more habitat in this area is at risk from unplanned development and, given the high human populations and rich soils, the challenges for providing a future for chimps in a period of climate change are substantial.
The authors of the paper titled “Chimpanzee population structure in Cameroon and Nigeria is associated with habitat variation that may be lost under climate change” are: Clee, P.R.S., Abwe, E., Ambahe, R.D., Anthony, N.M., Fotso, R., Locatelli, S., Maisels, F., Mitchell, M.W., Morgan, B.J., Pokempner, A.A., Gonder, M.K., 2014. Bmc Evolutionary Biology.
This study was made possible through the generous support of the Arcus Foundation, the U.S. Fish and Wildlife Great Apes Conservation Fund, and other partners.