Chimpanzees live in fission-fusion social organizations, which means that party size, composition, and spatial distribution are constantly in flux. Moreover, chimpanzees use a remarkably extensive repertoire of vocal and nonvocal forms of communication, thought to help convey information in such a socially and spatially dynamic setting. One proposed form of nonvocal communication in chimpanzees is buttress drumming, in which an individual hits a tree buttress with its hands and/or feet, thereby producing a low-frequency acoustic signal. It is often presumed that this behavior functions to communicate over long distances and is, therefore, goal-oriented. If so, we would expect chimpanzees to exhibit selectivity in the choice of trees and buttresses used in buttress drumming. Selectivity is a key attribute of many other goal-directed chimpanzee behaviors, such as nut-cracking and ant dipping. Here, we investigate whether chimpanzees at the Seringbara study site in the Nimba Mountains, Guinea, West Africa, show selectivity in their buttress drumming behavior. Our results indicate that Seringbara chimpanzees are more likely to use larger trees and select buttresses that are thinner and have a greater surface area. These findings imply that tree buttress drumming is not a random act, but rather goal-oriented and requires knowledge of suitable trees and buttresses. Our results also point to long-distance communication as a probable function of buttress drumming based on selectivity for buttress characteristics likely to impact sound propagation. This study provides a foundation for further assessing the cognitive underpinnings and functions of buttress drumming in wild chimpanzees.

中文翻译：

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打鼓还是不打鼓：几内亚宁巴山脉的黑猩猩（Pan troglodytes verus）在树墩上打鼓的选择性

黑猩猩生活在裂变融合的社会组织中，这意味着党的规模、组成和空间分布在不断变化。此外，黑猩猩使用非常广泛的声音和非声音形式的交流方式，被认为有助于在这种社会和空间动态的环境中传达信息。在黑猩猩中提出的一种非声音交流形式是支撑鼓，其中个体用手和/或脚敲击树支撑，从而产生低频声音信号。人们通常认为这种行为的功能是进行远距离通信，因此是面向目标的。如果是这样，我们希望黑猩猩在选择用于支撑击鼓的树木和支撑时表现出选择性。选择性是许多其他以目标为导向的黑猩猩行为的关键属性，例如咬坚果和浸蚂蚁。在这里，我们调查了位于西非几内亚宁巴山脉的 Seringbara 研究地点的黑猩猩是否在他们的支撑击鼓行为中表现出选择性。我们的研究结果表明，Seringbara 黑猩猩更有可能使用较大的树木并选择更薄且表面积更大的扶壁。这些发现表明，打树扶壁不是随机行为，而是以目标为导向，需要了解合适的树木和扶壁。我们的结果还指出，基于对可能影响声音传播的支撑特性的选择性，长距离通信是支撑击鼓的一个可能功能。