The characteristics of the tool-behavior of chimpanzees were studied at the Campo Animal Reserve, in the south-west corner of the Republic of Cameroon between December 1984 and January 1985. The study area comprised tropical rain forest of which the canopy reached 30 m in height. Although the chimpanzees were shy, evidence of the tool-behavior could be obtained.
No evidence of nut-cracking ofCoula edulis by the chimpanzees using stone or wood hammers was found, although mature trees of this species were common in the study area and their nuts were well known to be cracked by the chimpanzees of Tai, Côte d'Ivoire, using stone or wood hammers during the fruiting season. The termite-tunnel probing-stalk which is commonly used by the chimpanzees at Gombe, Tanzania, and a few other study sites may not be employed by the chimpanzees of the present study area for collecting termites from the inside of the nest. One hundred and ten termitemound digging-sticks were found on the surface ofMacrotermes mulleri nests. Some sticks were found stabbing into the mound and others were just left on the mound where the marks of crushing were sometimes observed. Some stumps and upper parts of young trees which were abandoned after making stick-tools were identified and some sticks were confirmed to have been carried away. The length of the sticks (30.5–73.5 cm,\(\bar x\)=46.8 cm) and their width (diameter) (4–15 mm,\(\bar x\)=9.9 mm) were similar to those noted at Rio Muni (Equatorial Guinea). However, nearly half of the sticks in the present study area had a “brush” at one end which was seldom clogged with mud. The brush might be used for catching termites effectively.
Local differences in the chimpanzee cultural patterns were examined and confirmed for crosscultural variation.