Figure 3. Flow chart describing the behavioural elements observed in chimpanzee accumulative stone throwing.

Three key behaviours were common to all observations of adult (N = 63) chimpanzee accumulative stone throwing (grey rectangles): 1) picking-up and handling a rock, 2) pant hoot introduction and/or build up phase, and 3) throwing the stone. Other behaviours were only sometimes observed or were observed in combination with one another (italicized). *Only 50 videos contained audio, all of which recorded a pant hoot vocalization.