New observations of ant-dipping techniques in wild chimpanzees at Bossou, Guinea

Ant-dipping behavior is often cited as a clear example of chimpanzee culture, since different populations have apparently different dipping techniques (the one-handed method used by chimpanzees in Bossou, Guinea and Taï, Côte d'Ivoire, and the two-handed method used in Gombe, Tanzania). Here we report a new observation of ant-dipping behavior from Bossou using the two-handed method, in addition to the first detailed description of the one-handed method. Although the main dipping pattern was the one-handed method in Bossou, one adult male was observed dipping for ants using the two-handed method, while other chimpanzees employed the conventional one-handed method in the same episode. The two-handed method was also sporadically observed in a juvenile and in adolescents, who were still immature in dipping techniques and hence prone to suffer from ant attacks. Cross-population comparisons of dipping techniques suggest that there are two sub-types of the one-handed method, and the Bossou one-handed technique may be substantially different from that of Taï. In terms of overall behavioral repertoire in ant dipping, the Bossou pattern appears more similar to that of Gombe than Taï. This may be explained by the difference in target ant species.