Wilhelm Wytse, Eleuteri Vesta, Koops Kathelijne, Fitzgerald Maegan, Zuberbühler Klaus, Hobaiter Catherine
Wild Minds Lab, School of Psychology and Neuroscience, University of St Andrews, Fife, United Kingdom.
Pathways to Language Group, Institute for Archaeological Sciences, University of Tübingen, Tübingen, Germany.
Am J Primatol. 2025 Jan;87(1):e23712. doi: 10.1002/ajp.23712.
Wild chimpanzees drum on tree buttresses during dominance displays and travel, generating low-frequency sounds that are audible over distances of more than 1 km. Western chimpanzees (Pan troglodytes verus) in the Nimba Mountains of Guinea selectively choose trees and buttresses when drumming, potentially based on their resonant properties, suggesting that these chimpanzees are optimizing their drumming signals. We investigated whether male eastern chimpanzees (Pan troglodytes schweinfurthii) from the Waibira community in the Budongo Forest, Uganda, also show preferences in tree and buttress choice, exploring whether selectivity is a species-wide feature. We tested chimpanzee preferences for tree species and diameter, number of buttresses, and buttress area and width, by comparing trees and buttresses used in drumming bouts with nearby unused trees and buttresses. Waibira chimpanzees drummed preferentially on two tree species: the tropical hardwood Cynometra alexandrii and the softwood Chrysophyllum albidum. Chimpanzees selected trees with a larger diameter over nearby trees with a smaller diameter, and buttresses were more likely to be used for drumming if they had a larger area or larger width. These results suggest that chimpanzees in the Waibira community select trees and buttresses based on physical properties, most likely related to acoustically relevant characteristics. These findings support the argument that buttress drumming is a goal-directed behavior and contributes to our understanding of chimpanzees' use and optimization of their long-distance acoustic signals.
野生黑猩猩在进行支配展示和移动时会敲打树木支柱，发出低频声音，这些声音在超过1公里的距离外都能听到。几内亚宁巴山的西部黑猩猩（Pan troglodytes verus）在敲打时会选择性地选择树木和支柱，这可能是基于它们的共振特性，这表明这些黑猩猩正在优化它们的敲打信号。我们调查了乌干达布东戈森林中来自韦比拉社区的东部雄性黑猩猩（Pan troglodytes schweinfurthii）是否也在树木和支柱的选择上表现出偏好，探究选择性是否是全物种的特征。我们通过比较敲打回合中使用的树木和支柱与附近未使用的树木和支柱，测试了黑猩猩对树种、直径、支柱数量以及支柱面积和宽度的偏好。韦比拉黑猩猩优先在两种树上敲打：热带硬木亚历山大银合欢和软木白花金叶树。黑猩猩会选择直径较大的树而非附近直径较小的树，并且如果支柱面积或宽度较大，就更有可能被用于敲打。这些结果表明，韦比拉社区的黑猩猩根据物理特性选择树木和支柱，这很可能与声学相关特征有关。这些发现支持了支柱敲打是一种目标导向行为的观点，并有助于我们理解黑猩猩对其长距离声学信号的使用和优化。
