Distribution of bonobos and their ecological characteristics.

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The aim of this research project was to clarify the distribution and ecological characteristics of bonobos (Pan paniscus) through the comparison with chimpanzees (Pan troglodytes). Unfortunately we could not carry out a field research of bonobos due to the war in D.R. Congo. However, we made studies on the population dynamics, conservation, habitat utilization, and the sexual behaviors of bonobos, using the data we had obtained since 1973.We studied chimpanzees in the Kalinzu Forest in Uganda, and in Ugala, Lilanshimba, and Rukuwa areas in Tanzania. In Kalinzu, we made close observations of habituated chimpanzees, and examined how ecological and sociological conditions affect ranging pattern and habitat utilization. We examined newly discovered hunting and tool use behaviors in the perspective of cultural differences of chimpanzees. We also made an ecological study of l'hoest monkey that had not been well studied in other sites. Furthermore, we carried out a survey of biomass of large mammals in, and evaluated the status of chimpanzees in the ecosystem in Kalinzu. Ugala and Lilanshimba are in a dried region, which are on the margin of the distribution of chimpanzees. By the observation of nests, food remains, and dang, we confirmed the existence of chimpanzees, and estimated their density. Chimpanzees in these areas were using both riverine forest and savanna. On the other hand, Rukuwa is the southern most limit of the chimpanzee distribution. Judging from their nests, the density of chimpanzees was extremely low, and they used only riverine forest. They seemed to be isolated from chimpanzees in the northern areas for a long time, and they might have become a different subspecies.Thus we found many new facts on the distribution and ecology of chimpanzees. We regret, however, that we could not reach to a overall conclusion about ecological characteristics of chimpanzees and bonobos.