Figure 1

Illustration of the total drumming bout and its division into 11 sequences.

Sequence 5 has less than 20 inter-beat durations and was not analyzed. At the end of the bout, the chimpanzee is on his arms and legs, quietly pushing and pulling the barrel on the floor in slow and wide circular movements. This part was not analyzed. Moving averages of the inter-beat duration of each sequence can be found in Supplementary Figure S1.