Confirmation of Bonobo Population around Lac Tumba
Ndunda Mwanza, Mbangi Mulavwa, Ihomi Mola, and Kumugo Yangozene


Bonobos (bilia, Pan paniscus) are reported from several isolated sites, e.g., Lomako, Ikela, Yalosidi, Salonga, Lukuru, Lilungu, Lui-Kotali, Koko Lopori, Wamba, and the west side of Lake Tumba. Among these, the bonobo population living between Lake Maindombe and Lake Tumba is most vulnerable.

Though bonobos were found in this area in the past (1, 2), the current situation of this population is unknown. Therefore, we, as researchers of the Research Center for Ecology and Forestry (CREF), carried out expeditions to confirm their presence. We also wanted to verify the existence of taboos against killing and eating bonobos since we were exploring the possibility of establishing a research site in this area and trying to encourage people in this area to conserve bonobos.

Two expeditions were organized: one in March and another in August-September 2002 with financial and materiel support from the Bonobo Conservation Initiative and the Wamba Committee for Bonobo Research.

On the first expedition, seven persons, including researchers and research assistants, formed two teams. We interviewed local people, mainly chiefs of villages, hunters, intellectuals and women, and collected materials or information that showed that bonobos were still surviving or had recently been killed around the village. When we obtained credible information, we entered the forest with local guides and collected information that showed the presence of bonobos.

On the second expedition, four persons formed two teams. We carried out surveys on the bed site, footprint, and bonobo trails in the savanna. For bed sites two days old or newer, feces were collected and analyzed to determine the fruits species eaten. We also tried to observe bonobos directly. We tried to find them when we heard their vocalization. When we found bonobos, we counted the number of animals within the group and recorded the age/sex composition as far as possible. We also recorded species name and part eaten of the plants that bonobos fed on. The survey was made for 9 forest blocks, including Malinda/Mantuna, Eboya/Lwaka, Lokole/Bokupa, Bobele, Lokele, Itota, Molungola/Moholo, Nkamba, and Bosango (Figure 1).

Attitudes of Local People

During two expeditions, we interviewed 26 local people. All of them were very familiar with the species, but the name “bonobo” was new to 22 persons. The popular name was “elia” (plural forms were “bilia”), or “mokomboso.” The name “mokomboso” meant both Pan troglodytes and Pan paniscus, while “elia” specifically meant Pan paniscus. This was probably because the distribution of Pan paniscus is mostly limited in the area of Mongo ethnic groups and “elia” is a term of Mongo language, while “mokomboso” is a term of Lingala, which is a common language of D.R. Congo. The term “bonobo” has no ethnic root.

Twenty-four persons admitted that they had been eating bonobo meat two times a year on average, and they liked it very much. The tribe Mpama of Bosango learned about eating bonobo meat from other ethnic groups like Ntomba, but they conserved the myth that the bonobo is not an ordinary animal but a relative of human beings. In Bosango, there were several histories telling that bonobos are like humans in their mind and behavior. Two persons in Botwali and Gondola said that bonobos were harmful to the cultivation of sugar cane. This meant that bonobos were sometimes coming close to villages. Fresh bones and skin with bonobo hair were found in Miale, Bosango I, Bosango II and Mokeli villages, which had been conserved as traditional medicines.

Thus the human pressure on bonobos was considerably high in the surveyed area, but after our campaign, local people promised to abandon this habit.

Current Status of Bonobos and their Habitat

Three biotopes were remarkably distinct in the area: swamp forests, terra firma forests, and savannas. Fauna was not abundant. In spite of hunting activities by traps and shotguns, large mammals, including wild pigs (Potamochoerus porcus), sitatungas (Tragelaphus spekei), several antelopes, rodents and small carnivores, were still present. However, some species recorded previously, including elephants (Loxodonta africana cyclotis), buffalos (Syncerus cafer nanus) and leopards (Panthera pardus), had completely disappeared.

We found beds of bonobos in 8 of 9 forest blocks. We counted 294 beds, including 129 new and 165 old ones. Eboya/Lwaka forest block seemed to have more bonobos than other forests. Though we could not decide on the site for future study, this forest seemed to be most promising.

We directly observed bonobos in 4 of the 9 forest blocks. In spite of human pressure, these bonobos did not flee but observed us. We made direct observation during 383 minutes and we counted 54 animals in total. These included: 11 animals in Malinda/Mantuna for 56 and 156 min; 13 animals in Eboya/Lwaka for 80 min; 10 animals in Bobele for 73 min; and 20 animals in Nkamba for 8 min. The bonobos observed in Nkamba forest might be a fusion of two groups.

In the survey made in 1981, Mbangi and other researchers observed one group of 10 bonobos in Bobele. Twenty years later the same number of bonobos was observed in the same forest block. We suppose that human pressure on bonobos in this area might be lower than we had predicted. This might be because local people killed bonobos for their own use but sold meat very rarely.


We confirmed that bonobos were still surviving on the west side of Lake Tumba, but there remained various kinds of threats from humans. Immediate and effective actions were required to protect this vulnerable population of bonobos from poachers and commercial wood exploitation by SCIBOIS, an enterprise that was negotiating for concessions in this area.

Bonobos were usually ranging far from human villages, but in Bosango we had information that they sometimes visited fields to eat sugar cane. The fact that a similar number of bonobos were observed in the same forest as 20 years ago showed the existence of equilibrium between people and bonobos. However, this equilibrium is very shaky. It is time to start intensive studies in this area and to conduct conservation programs before the situation gets worse.


  1. Nishida T 1972. Preliminary information of the pygmy chimpanzees (Pan paniscus) of the Congo Basin. Primates 13: 415-425.
  2. Horn AD 1980. Some observations on the Ecology of the Bonobo Chimpanzee (Pan paniscus, Schwarz 1929) near Lake Tumba, Zaire. Folia primatol 34: 145?169.

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