The Forms and Structures of Chimpanzee Algae Fishing

Variation in the expression of behavior is a critical measure for understanding how socio-ecological factors shape cognitive and behavioral evolution and adaptability. Detailed descriptions of behavioral repertoires, and how they are combined and structured into programs of actions is an essential foundation for this work. However, comparisons within and across species are made challenging where there is substantial variation in the level of detail at which behaviors are described. Here, we use a systematic, multi-level framework to describe a recently reported chimpanzee tool use behavior—algae fishing—at three levels of granularity: Functional Behavioral Categories, Behaviors, and Behavioral Elements. We then describe how these units combine into structured programs of action. We show that chimpanzees’ algae fishing repertoire is relatively large, as compared to other forms of chimpanzee tool using, and flexibly deployed at each level of description. Adult chimpanzees use a diverse set of algae fishing techniques, suggesting that they benefit from retaining multiple solutions to this dynamic foraging challenge. We highlight the importance of matching the level of detail in descriptions of behavior to the question being addressed. We provide an example of a structured framework that can be applied to describe different levels of detail and used to show within- and between- task variation. Systematic coding frameworks that can be consistently applied are critical for providing the like-with-like comparisons necessary for robust investigations of species-level cognition and behavior, as well as for tailoring targeted conservation action.