Mausbach Jelena, Braga Goncalves Ines, Heistermann Michael, Ganswindt André, Manser Marta B
Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
Kalahari Meerkat Project, Kuruman River Reserve, Van Zylsrus, Northern Cape, South Africa.
PLoS One. 2017 May 3;12(5):e0175371. doi: 10.1371/journal.pone.0175371. eCollection 2017.
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. Fecal GCM 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.
动物发声能够编码有关发声者的身份、性别、年龄、体型、社会等级和群体成员身份等信息，这一点已得到充分证实。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仍未得到很好的理解。合作繁殖的非洲狐獴（Suricata suricatta）生活在具有专制社会等级制度的家庭群体中。在觅食过程中，个体会发出近距离叫声以帮助维持群体凝聚力。这些接触叫声在声学上具有独特性，且个体之间的发声频率各不相同，然而，关于哪些因素影响近距离叫声行为的信息却缺失了。本研究的目的是确定影响狐獴近距离叫声频率和声学结构变化的近端因素。具体而言，我们调查了近距离叫声行为是否与性别、年龄和等级相关，或者是否与作为发声者个体特征的应激激素输出（即通过粪便糖皮质激素代谢物（fGCM）浓度来衡量）以及环境条件（天气）和繁殖季节性相关。为了厘清这些因素对发声行为的影响，我们分析了录音，并评估了9个群体中64只野生但已习惯人类存在的狐獴在繁殖季节和非繁殖季节的fGCM浓度。在繁殖季节，占主导地位的雌性和一岁雄性的叫声频率明显高于其他社会类别。此外，占主导地位的雌性发出的近距离叫声平均基频（F0）最低，平均脉冲持续时间最长。在非繁殖季节，有风的条件与明显更高的叫声频率相关。粪便GCM浓度与近距离叫声行为无关。我们的研究结果表明，狐獴的近距离叫声行为传达了有关发声者性别和社会类别的信息，但与fGCM浓度无关。叫声频率随个体所经历的社会和生态环境变化而变化，这表明发声产生具有一定程度的灵活性。
