Unit groups of chimpanzees and their nomadism in the savanna woodland

Abstract

I chose an area in the savanna woodland of Western Tanzania covering about 45 km2 and made an intensive sociological study of the chimpanzees visiting this area. Three components constituting a chimpanzee population were recognized: large-sized groups, smallsized groups, and lone individuals. I took notice of the groupings of large-sized groups, and classified them into the following three statuses: the state of congregation, the state of partition, and the state of dispersion. Provided that the productivity of food was stable, large-sized groups carried on their nomadism regularly, no matter what their main food might be. During the period in which the food supply was scarce, however, large-sized groups presented two types of nomadism: rapid movement in the state of congregation, and extreme dispersion. Two large-sized groups were found and each had its own nomadic range of about 120 km2 respectively, 20% of which overlapped. Small-sized groups and lone individuals did not have their own ranges, and it is possible that they moved over wider ranges than the large-sized groups.