Male copulation calls sometimes play important roles in sexual strategies, attracting conspecific females or advertising their social status to conspecific males. These calls generally occur in sexually competitive societies such as harem groups and multi-male and multi-female societies. However, the call functions remain unclear because of limited availability of data sets that include a large number of male and female animals in naturalistic environments, particularly in primates. Here, we examined the possible function of male-specific copulation calls in wild stump-tailed macaques (Macaca arctoides) by analyzing the contexts and acoustic features of vocalizations. We observed 395 wild stump-tailed macaques inhabiting the Khao Krapuk Khao Taomor Non-Hunting Area in Thailand and recorded all occurrences of observed copulations. We counted 446 male-specific calls in 383 copulations recorded, and measured their acoustic characteristics. Data were categorized into three groups depending on their social status: dominant (alpha and coalition) males and non-dominant males. When comparing male status, alpha males most frequently produced copulation calls at ejaculation, coalition males produced less frequent calls than alpha males, and other non-dominant males rarely vocalized, maintaining silence even when mounting females. Acoustic analysis indicated no significant influence of status (alpha or coalition) on call number, bout duration, or further formant dispersion parameters. Our results suggest that male copulation calls of this species are social status-dependent signals. Furthermore, dominant males might actively transmit their social status and copulations to other male rivals to impede their challenging attacks, while other non-dominant males maintain silence to prevent the interference of dominants.

中文翻译：

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泰国雄性断尾猕猴的优势地位和交配发声

雄性交配有时在性策略中发挥重要作用，吸引同种雌性或向同种雄性宣传其社会地位。这些电话通常发生在性竞争社会，例如后宫团体和多男多女社会。然而，由于数据集的可用性有限，其中包括自然环境中的大量雄性和雌性动物，尤其是灵长类动物，因此调用函数仍不清楚。在这里，我们通过分析发声的背景和声学特征，研究了野生断尾猕猴（Macaca arctoides）中雄性特异性交配呼叫的可能功能。我们观察了 395 只栖息在泰国 Khao Krapuk Khao Taomor 非狩猎区的野生断尾猕猴，并记录了观察到的所有交配事件。我们在记录的 383 次交配中计算了 446 次男性特有的呼叫，并测量了它们的声学特征。数据根据其社会地位分为三组：支配（阿尔法和联盟）男性和非支配男性。在比较男性状态时，阿尔法雄性在射精时最常发出交配叫声，联盟雄性发出的呼叫频率低于阿尔法雄性，其他非优势雄性很少发声，即使在雌性上马时也保持沉默。声学分析表明状态（阿尔法或联盟）对呼叫号码、回合持续时间或其他共振峰色散参数没有显着影响。我们的研究结果表明，该物种的雄性交配是社会地位相关的信号。此外，