Herbrich Maxime, Sands Emily, Ishizuka Shintaro, Kaigaishi Yu, Yamamoto Shinya, Sueur Cédric
Université de Strasbourg, IPHC UMR7178, CNRS, Strasbourg, France.
Ecole Normale Supérieure, Lyon, France.
Primates. 2025 Mar;66(2):207-219. doi: 10.1007/s10329-024-01178-w. Epub 2024 Dec 27.
Huddling behaviour is present in many animal species. This behaviour involves maintaining close physical contact with conspecifics to minimise heat loss and, in general, reduce energy expenditure. Additionally, this behaviour also facilitates complex social interactions within a population. In Japanese macaques, this behaviour is observed in many populations across Japan, including Shodoshima, where huddling clusters can reach up to 100 individuals in winter. Based on several studies on this species, it appears that huddling, or sarudango in Japanese, is influenced by both meteorological factors and social relationships between individuals. The objective of this study is to understand the determinants that drive the expression (presence or absence) and the organisation (number of individuals and identities) of huddling clusters. Two hypotheses were formulated. The first hypothesis posits that the formation and variations in the size and number of clusters are influenced by meteorological factors, while the second hypothesis suggests that the number and position of individuals within a cluster are related to existing relationships between individuals. To test these, data on the number, size, and individuals composing a cluster were collected, allowing building huddling social networks. Simultaneously, meteorological measurements were taken, along with observations on dominance and grooming interactions between individuals. This allowed us to create several statistical models and social networks for comparison. Our results suggest that the probability for observing huddling is mainly related to solar radiation energy, while variations in number and size could be explained by temperature. Moreover, the organisation within a cluster is not random but reflects relationships between individuals. The ones sharing more grooming and having similar dominance ranks have more probabilities to be in the same huddling cluster.
抱团行为存在于许多动物物种中。这种行为包括与同种个体保持紧密的身体接触，以尽量减少热量损失，并总体上减少能量消耗。此外，这种行为还促进了种群内复杂的社会互动。在日本猕猴中，这种行为在日本各地的许多种群中都有观察到，包括小豆岛，在冬季，抱团群体可达100只个体。基于对该物种的多项研究，似乎抱团行为，或日语中的“猿団子”，受到气象因素和个体间社会关系的影响。本研究的目的是了解驱动抱团群体表现（存在或不存在）和组织（个体数量和身份）的决定因素。提出了两个假设。第一个假设认为，群体大小和数量的形成及变化受气象因素影响，而第二个假设表明，群体内个体的数量和位置与个体间现有的关系有关。为了验证这些假设，收集了关于群体数量、大小和组成个体的数据，从而构建抱团社会网络。同时，进行了气象测量，并观察了个体间的支配和梳理互动。这使我们能够创建几个统计模型和社会网络进行比较。我们的结果表明，观察到抱团行为的概率主要与太阳辐射能量有关，而数量和大小的变化可以用温度来解释。此外，群体内的组织并非随机，而是反映了个体间的关系。那些有更多梳理互动且支配等级相似的个体更有可能处于同一个抱团群体中。
