@article {331926, title = {Stone-assisted drumming in Western chimpanzees and its implications for communication and cultural transmission}, journal = {Biology Letters}, volume = {21}, year = {2025}, note = {

doi: 10.1098/rsbl.2025.0053

}, month = {2025/05/07}, pages = {20250053}, abstract = {

Chimpanzees (Pan troglodytes) communicate in complex ways, including sounds produced by hand and foot drumming on trees, often combined with loud vocalizations. Recently, a puzzling stone throwing behaviour at trees was observed, resulting in stone piles at tree buttresses. It is a rare case of tool used for communication in animals and suggested to function like buttress drumming in long-distance communication and male displays. We tested this hypothesis by determining the behavioural dynamics in comparison to hand and foot tree buttress drumming in Western chimpanzees in Bo{\'e}, Guinea Bissau. Using camera traps, we show that in 78\% of cases, stones were picked up at trees, not leading to further stone accumulation beyond the already existing stone piles. Stone-assisted and hand and foot drumming occurred separately or were combined in similar behavioural contexts in apparent long-distance communication and highly aroused behavioural contexts. Yet, immediately before stone drumming, chimpanzees swayed less and pant-hooted more while afterwards pant-hooting less compared to the other contexts, suggesting a separate motivation and/or function for stone-assisted drumming. It suggests this unique stone-based activity has its own signal value, separate from hand/foot buttress drumming and, considering the spatial variation, might be culturally transmitted.

}, doi = {https://doi.org/10.1098/rsbl.2025.0053}, url = {https://royalsocietypublishing.org/doi/10.1098/rsbl.2025.0053}, author = {van Loon, Sem and Heitk{\"o}nig, Ignas M. A. and Goedmakers, Annemarie and Mundry, Roger and Naguib, Marc} }