Academy of Emerging Science, Chubu University, Inuyama, Aichi, 484-8506, Japan.
Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan.
Primates. 2020 Sep;61(5):685-694. doi: 10.1007/s10329-020-00820-7. Epub 2020 Apr 21.
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.
雄性交配叫声在某些情况下可能在性策略中发挥重要作用，例如吸引同种雌性或向同种雄性展示其社会地位。这些叫声通常发生在具有性竞争的社会中，例如后宫群体和多雄性-多雌性社会。然而，由于缺乏包括大量自然环境中的雄性和雌性动物的数据集，这些叫声的功能仍然不清楚，尤其是在灵长类动物中。在这里，我们通过分析叫声的背景和声学特征，研究了野生短尾猴（Macaca arctoides）雄性特有的交配叫声的可能功能。我们观察了 395 只栖息在泰国考克拉布考塔莫尔非狩猎区的野生短尾猴，并记录了所有观察到的交配行为。我们在 383 次记录的交配中，共记录到 446 次雄性特有的叫声，并测量了它们的声学特征。根据其社会地位，将数据分为三组：优势雄性（阿尔法和联合雄性）和非优势雄性。在比较雄性地位时，阿尔法雄性在射精时最常发出交配叫声，联合雄性比阿尔法雄性发出的叫声频率较低，而其他非优势雄性很少发声，甚至在骑雌性时保持沉默。声学分析表明，地位（阿尔法或联合）对叫声数量、鸣叫持续时间或进一步的共鸣器分散参数没有显著影响。我们的结果表明，该物种的雄性交配叫声是社会地位依赖的信号。此外，优势雄性可能会主动向其他雄性竞争对手传达其社会地位和交配信息，以阻止它们的挑战攻击，而其他非优势雄性则保持沉默，以防止被优势雄性干扰。
