Data from: Meerkat close calling patterns are linked to sex, social category, season and wind, but not fecal glucocorticoid metabolite concentrations

It is well established that animal vocalizations can encode information regarding a sender’s identity, sex, age, body size, social rank and group membership. However, the association between physiological parameters, particularly stress hormone levels, and vocal behavior is still not well understood. The cooperatively breeding African meerkats (Suricata suricatta) live in family groups with despotic social hierarchies. During foraging, individuals emit close calls that help maintain group cohesion. These contact calls are acoustically distinctive and variable in rate across individuals, yet, information on which factors influence close calling behavior is missing. The aim of this study was to identify proximate factors that influence variation in call rate and acoustic structure of meerkat close calls. Specifically, we investigated whether close calling behavior is associated with sex, age and rank, or stress hormone output (i.e., measured as fecal glucocorticoid metabolite (fGCM) concentrations) as individual traits of the caller, as well as with environmental conditions (weather) and reproductive seasonality. To disentangle the effects of these factors on vocal behavior, we analyzed sound recordings and assessed fGCM concentrations in 64 wild but habituated meerkats from 9 groups during the reproductive and non-reproductive seasons. Dominant females and one-year old males called at significantly higher rates compared to other social categories during the reproductive season. Additionally, dominant females produced close calls with the lowest mean fundamental frequencies (F0) and the longest mean pulse durations. Windy conditions were associated with significantly higher call rates during the non-reproductive season. FGCM concentrations were unrelated to close calling behavior. Our findings suggest that meerkat close calling behavior conveys information regarding the sex and social category of the caller, but shows no association with fGCM concentrations. The change in call rate in response to variation in the social and ecological environments individuals experience indicates some degree of flexibility in vocal production.

学界已达成共识：动物发声可传递发出者的身份、性别、年龄、体型、社会等级及群体归属等信息。然而，生理参数（尤其是应激激素水平）与发声行为之间的关联，目前仍未得到充分阐释。具备合作繁殖特性的非洲狐獴（Suricata suricatta）以家族群体为单位聚居，群体内存在专制式社会等级结构。在觅食过程中，狐獴个体常会发出近距离叫声，以维持群体凝聚力。这类联络叫声在声学特征上具有个体特异性，且个体间的呼叫率存在显著差异，但目前仍缺乏关于哪些因素会影响狐獴近距离叫声行为的相关研究。
本研究旨在明确影响狐獴近距离叫声的呼叫率与声学结构变异的近因因素。具体而言，我们探究了狐獴的近距离叫声行为是否与发出者的性别、年龄、社会等级以及应激激素水平（以粪便糖皮质激素代谢物（fecal glucocorticoid metabolite, fGCM）浓度为衡量指标）等个体特征相关，同时也探究了其与环境条件（天气状况）及季节性繁殖状态的关联。
为厘清上述各类因素对发声行为的影响，本研究在繁殖季与非繁殖季期间，对来自9个群体的64只已习惯人类观察的野生狐獴开展了声音录制分析，并检测了其粪便中的fGCM浓度。结果显示：在繁殖季，优势雌性与一岁龄雄性的呼叫率显著高于其他社会类群的个体；此外，优势雌性发出的近距离叫声平均基频（fundamental frequency, F0）最低，平均脉冲时长最长。在非繁殖季，大风天气与更高的呼叫率存在显著关联。粪便糖皮质激素代谢物浓度与狐獴的近距离叫声行为并无关联。
本研究结果表明，狐獴的近距离叫声行为可传递出发出者的性别与社会类群信息，但与粪便糖皮质激素代谢物浓度不存在关联。呼叫率会随个体所处的社会与生态环境变化而改变，这说明狐獴的发声过程具备一定程度的可塑性。