Algae Scooping Remains a Puzzle

Algae scooping is a tool-use signature marker of the Bossou chimpanzee community, as it is unique to this community and has never been observed at any other chimpanzee field site in Africa. Bossou chimpanzees use different techniques to feed on free-floating species of filamentous algae of the genus Spyrogyra available at the surface of ponds. However, the chimpanzees mainly rely on stick or stalk tools to gather the algae. This tool-use behavior is seasonal and occurs predominantly during rainy season months. A majority of tools were made from only two plant species. The availability of these plants beside ponds needs to be evaluated in the future to test whether the chimpanzees are purposely selecting those species over others. Differences in algae-feeding techniques recorded at Bossou may reveal interesting intracommunity patterns of social transmission. In addition, it is hypothesized that the chimpanzees select tools depending on algae abundance at the ponds’ surface to maximize proficiency as well as efficiency. Future perspectives are also discussed with regard to sex differences in algae scooping, with males performing algae scooping significantly more often than females, and the nutritional content of Spirogyra.