Pan troglodytes verus
"At the beginning of the 20th century, there were between 1 and 2 millions of chimpanzees occupying 25 African countries. Even in 1960, when I started my research with chimpanzees in Tanzania, there was at least one million of them, although they had already disappeared in 2 or 3 nations. Today, 57 years later, it is believed that there are less than 250,000 individuals left." - Jane Goodall.
Chimpanzees (Pan troglodytes) are one of the species of great apes that inhabit the planet and they are in the wild in tropical Africa. Together with the bonobos (Pan paniscus), chimpanzees are the closest species to humans in physical, behavioral and genetic terms (there is only a genetic difference between the chimpanzees and us of about 1,4%), so the study of chimpanzees provides an important approach for the knowledge of our evolutionary history. They are extremely social and intelligent animals, with high cognitive abilities for learning. A large number of behaviors are transmitted from generation to generation, which means that chimpanzees have cultural behaviors.
Chimpanzees are characterized for having an omnivorous diet, very variable depending on the population and seasonality, although the fruit consumption is a large part of their diet. They are predominantly found in humid and dry forests, also occupying gallery forests and being able to extend to savanna lands. In wild conditions, chimpanzees can live up to 40 years. To sleep, they build nests every night at the top of trees and they are selective when choosing the tree to build their nest. Some young females migrate leaving behind their natal group, while the males remain in it (they would not be accepted by males from other territorial groups).
Chimpanzees form social communities of between 5 and 150 individuals and have a social structure of fission-fusion, where sometimes less stable subgroups are formed, representing only a part of the whole group. This dynamic and social structure allows more flexibility when exploiting food, when resources are more or less limited due to seasonality. Chimpanzees use complex social interactions and show cooperative, alliance-building and reconciliation skills. The groups have hierarchical structures, where the adult males dominate (starting with the alpha male), although the females have hierarchies among them. They exhibit affiliative grooming behavior, which on the one hand has a hygienic function and, on the other, serves as a social tool to reinforce links between individuals, reduce tension or to create alliances between unrelated individuals.
On a regular basis, chimpanzees build and use a diverse tool repertoire to gain access to certain food, use them as a weapon or improve their comfort. It was the doctor Jane Goodall who discovered in 1960 the use of tools by chimpanzees during her studies in Gombe, Tanzania, and she eradicated the belief that humans were the only animals capable of creating and using tools. Subsequent research has proven that other animal species use tools. 4 chimpanzee subspecies are known for their extensively design and use of tools and it can be observed even the use of up to 54 tools with different repertoires depending on the area of Africa where they live and discoveries and generational knowledge transfer that they have made.
In spite of the wide distribution of the common chimpanzee across the African continent, their populations have decreased more than 66% in the last 30 years; therefore, chimpanzee is nowadays an endangered species, cataloged under this category by the International Union for the Conservation of Nature (IUCN) and it is in risk of disappearing in the coming years if no actions are taken in this regard.
Four chimpanzee subspecies are recognised: the chimpanzee of Western Africa (Pan troglodytes verus), the Nigeria-Cameroon chimpanzee (Pan troglodytes ellioti – formerly called vellerosus), the Central Africa chimpanzee (Pan troglodytes troglodytes), and the chimpanzee of Eastern Africa (Pan troglodytes schweinfurthii).
The team of the Jane Goodall Institute in Senegal, established in the Dindefelo Natural Community Reserve, in southeastern Senegal, focused the research in the chimpanzee subspecies of Western Africa (Pan troglodytes verus).
The chimpanzee of Western Africa (Pan troglodytes verus)
Physical features and characteristics:
The chimpanzee of Western Africa is characterized for presenting dark skin around the eyes, a light muzzle that becomes darker with age, baldness; although not as pronounced as in the chimpanzee of Central Africa, and a white or grey beard.
Adaptation to the savanna
In the Dindefelo Natural Community Reserve (Senegal) the subspecies lives in one of the driest and warmest regions of its total distribution area and we refer to it as savanna chimpanzee for its adaptation to this type of habitat.
Instrumental behavior
This subspecies uses diverse types of tools in the countries where inhabits and is notably known for cracking nuts with hammers and anvils (e.g. in Guinea or Ivory Coast), although this behavior has not been registered yet in the Dindefelo Natural Community Reserve, whereas using small tree branches for fishing termites is the most prominent cultural behavior among chimpanzees in this region. Fishing algae with sticks in Guinea and hunting bushbabies with spears made of sharp branches with the teeth in Senegal have also been discovered. Some groups have other striking behaviors such as visiting caves or getting into the water in order to cool off.
Geographic distribution
They are spread out from Southeastern Senegal to the Niger River in Nigeria or Togo-Dahomey Gap, the region of jungle and savanna mosaic of Guinea that extends to the coast of Benin, Togo and Ghana.
Conservation status
The chimpanzee of Western Africa (Pan troglodytes verus) is one of the two most endangered chimpanzee subspecies together with the chimpanzee of Nigeria-Cameroon (Pan troglodytes ellioti). In 2003, the total number of individuals of P.t. verus was estimated in between 21.300 and 55.600 by Kormos et al., being its largest population in Guinea. The chimpanzee of Western Africa is extinct in Togo and Gambia, potentially extinct in Benin and it could soon be pushed to the extinction in Burkina Faso, Senegal – in 2001 Butynski estimated the number of chimpanzees in Senegal between 200 to 400 individuals- and Ghana. The IUCN cataloged this subspecies as "critically endangered" on the 2016 Red List.
Threats
The fragmentation and loss of habitat as a result of human activities such as deforestation, either by cutting trees down or because the establishment of crop fields and fires, are some the biggest threats that chimpanzees suffer in West Africa in Senegal, along with the construction of infrastructures (water damn, high-tension lines & towers, roads, etc). For this reason, many populations of this subspecies are isolated in patches of forest which compromises their long-term survival. Fortunately, neither poaching nor illegal trafficking of chimpanzees are currently the main threat for the survival of this subspecies in Senegal but they are a threat in Guinea and other countries.
