Wild chimpanzees face extinction
Mankind’s closest living relatives – chimpanzees – are disappearing from the earth, because their habitats are destroyed and they are being eaten into extinction
In May 2019, over 40 scientists met at a symposium in Leipzig, Germany, to talk about the wild chimpanzee populations that they have been studying for decades. The occasion was the 40th anniversary of a long-term research and conservation project on chimpanzees in the Taï National Park, Côte d’Ivoire.
Altogether, the researchers represent over 300 years of experience with chimpanzees in their natural habitats. Despite working in eight different countries, their conclusions about population trends are all pressingly similar: the healthy chimpanzee populations that they study have been consistently “islandized”. Over the decades that we have been working with wild chimpanzee communities, we have all seen our study groups become isolated from their direct natural surrounding by the development of agriculture, by new or growing human settlements, or by turning forests into wasteland. Chimpanzees are being reduced into living in forest ghettoes.
Christophe Boesch, who has worked for 40 years in the Taï National Park in Côte d’Ivoire, said: “Forty years ago, we had to drive for 100 km on a mud-road to reach the park boundaries while encountering chimpanzees and elephants. Nowadays, you have to reach the park boundaries to see the first wild patch of forest and reach the research camp to have a chance to hear and see chimpanzees. Poaching is a constant threat to the individuals and we constantly fear to lose one more of our well-known group members.”
Crickette Sanz, who has worked for decades in the Goualougo Triangle in the Republic of Congo, said: “When we first arrived in the Ndoki forest, the chimpanzees would often approach us with curiosity. It is likely that we were the first humans they had ever met and they seemed to trust us. Now elephant poachers have arrived, and it is wise that the chimpanzees have changed their behavior. Their survival depends on it.”
Richard Wrangham, who has worked for 30 years in the Kibale National Park, Uganda, confirms: “When I arrived in Kibale, there were many patches of forest around the park still being used by chimpanzees. Now almost all the forest outside the Park has disappeared, and chimpanzees can be found only inside the Park. I used to follow chimpanzees for several kilometers beyond the Park boundaries, but nowadays the forest is gone and they never venture into those areas.”
Anne Pusey, who has worked for over 40 years in Gombe National Park in Tanzania, stressed that: “Since I started working in Gombe, the park has become a small island surrounded by dense farmland, leading to shrinkage of two of the three communities within the park and disappearance of communities outside. Nevertheless, work by the Jane Goodall Institute with local communities around the park led to the establishment of village forest reserves in the highlands that have increased connections with remaining populations outside the park and recent emigration has been documented.”
The great anthropologist Irven DeVore said once: “If we, in our travels in space, should encounter a creature that shares 98% of our genetic makeup, think of the money we would spend to study this species. Such creature exists on earth and we are allowing them to become extinct.”
Evidence shows that the permanent presence of researchers and local field assistants results in higher chimpanzee numbers and biodiversity compared to areas without research presence. Research represented at the symposium shows that nonetheless pressure on chimpanzee habitat is now so high that even healthy chimpanzee populations are affected by its growing isolation and reduced opportunities for dispersal and immigration.
Appeal of the long-term chimpanzee field researchers:
- We need to document the situation on the ground: For this, all projects in Africa should contribute data about chimpanzee signs, direct observations and distribution to the IUCN- Great Apes Database (http://apesportal.eva.mpg.de).
- We need to protect healthy chimpanzee research populations before it is too late: Known healthy populations should be the subject of special intense protection activities by researchers and by the local authorities. Other unknown healthy chimpanzee populations certainly exist, but as long as they are not followed, we do not know about them. That is why it is urgent to protect the known ones before the pressures becomes too strong.
- Protect chimpanzee population behavioral diversity: All our populations are unique in the way they behave, the way they are socially organized and the way they interact with their environment. More money needs to be invested in research so that we can fully understand chimpanzee population diversity before it is too late!
Under signees come from the following different long-term research projects: Gombe Stream Research Centre (Gombe National Park, Tanzania), Mahale Mountain Chimpanzee Research Project (Tanzania), Ngogo Chimpanzee Project (Kibale National Park, Uganda), Budongo Conservation Field Station (Budongo Forest, Uganda), Taї Chimpanzee Project (Taї National Park, Côte d’Ivoire), Fongoli Savanna Chimpanzee Project (Senegal), Goualougo Triangle Chimpanzee Project (Republic of Congo), Loango Chimpanzee Project (Loango National Park, Gabun), Chimpanzee Project (Miombo Woodland, Tanzania), Kalinzu Central Forest Reserve (Uganda), Pan African project: The Cultured Chimpanzee.
All chimpanzee subspecies are classified on the IUCN Red List as Endangered or Critically Endangered – meaning they could disappear forever in the near future (Humle et al. 2016). The western chimpanzee (Pan troglodytes verus) was listed as Critically Endangered in September 2016, because the total population loss over a three-generation period is estimated to exceed 80% (Kühl et al. 2017). This subspecies is already extinct in Benin, Burkina-Faso and Togo and has low numbers in Ghana, Guinea-Bissau and Senegal. The population in Côte d’Ivoire has declined by 90% (Campbell et al. 2008).
The Nigeria-Cameroon chimpanzee (Pan troglodytes ellioti) listed as Endangered, is the least numerous subspecies. One of the largest and probably most secure subpopulations is in Gashaka-Gumti National Park, Nigeria, estimated at 900–1,000 individuals (Ogunjemite et al. 2010, Adanu et al. 2011). Other subpopulations are found in Cameroon (Maisels et al. 2009).
The central chimpanzee (Pan troglodytes troglodytes) listed as Endangered, is found in Gabon, Congo, Cameroon, Equatorial Guinea, Democratic Republic of Congo, Angola, Central African Republic. The forests of central Africa are by far the least disturbed in the species’ range.
The eastern chimpanzee (Pan troglodytes schweinfurthii) listed as Endangered, is mainly found in the Democratic Republic of Congo (173,000–248,000, Plumptre et al. 2010, 2015). There are roughly 5,000 in Uganda (Plumptre et al. 2003), just over 400 in Rwanda (WCS Rwanda), fewer than 400 in Burundi (Hakizimana and Huynen 2013), and fewer than 2,500 in Tanzania.
A recent study showed a reduction in behavioral diversity of chimpanzees when human impact was high (Kühl et al. 2019). Much of the empirical work and resulting debate on the loss of wildlife biodiversity has been conducted in the context of species decline or loss of genetic diversity and ecosystem functions. However, behavioral diversity is also a facet of biodiversity which humans are destroying.