Department of Anthropology, The CUNY Graduate Center, New York, NY, USA.
New York Consortium in Evolutionary Primatology, New York, NY, USA.
Primates. 2022 Jan;63(1):79-91. doi: 10.1007/s10329-021-00956-0. Epub 2021 Oct 22.
Vocal communication is an important modality for group-living primates inhabiting dense forest habitats that can hinder visual and olfactory signals. Nevertheless, research on primate vocalizations has historically focused on a narrow subset of haplorhine taxa; comparatively few studies have been focused on strepsirrhines, despite facing similar ecological and social challenges. Ruffed lemurs (Varecia)-a taxon known for their raucous calls-are rainforest specialists that exhibit strong fission-fusion dynamics and communally rear large litters of young. However, surprisingly few studies have examined Varecia vocalizations in the wild, meaning virtually nothing is known about the call types or how they facilitate their unique social and reproductive strategies. Our goal for this study was to examine how various contextual factors such as weather, behavioral state, and subgroup size and composition affected vocal activity across call types in wild black-and-white ruffed lemurs. We conducted focal follows on 31 individuals (two communities) in Mangevo (Ranomafana National Park) from May-August 2019 to record behavioral and vocal activity. We distinguished 11 call types, although three (hum, roar-shriek, chatter) constituted the majority of vocal activity. Calling rates were consistent throughout the day, but decreased with high rainfall. We found sex- and subgroup-specific differences in call usage, likely related to female dominance and subgroup composition, respectively. We identified behavioral contexts that some call types were consistently given in; this can be used to help infer call function. This study provides some of the first quantitative analyses of ruffed lemur vocal communication and lays the groundwork for more systematic hypothesis testing in future studies.
声音交流是生活在茂密森林中的群居灵长类动物的一种重要方式，因为茂密的森林会阻碍视觉和嗅觉信号的传递。然而，尽管面临类似的生态和社会挑战，灵长类动物叫声的研究历史上一直集中在少数几个原猴类分类群上；相对而言，针对树鼩的研究却很少，尽管树鼩也面临着类似的生态和社会挑战。毛吼猴（Varecia）——一种以刺耳叫声而闻名的灵长类动物——是雨林的专家，它们表现出强烈的分裂-融合动态，并共同养育大量的幼崽。然而，令人惊讶的是，很少有研究在野外研究毛吼猴的叫声，这意味着人们几乎不知道它们的叫声类型，也不知道这些叫声是如何帮助它们实现独特的社会和繁殖策略的。我们这项研究的目的是研究各种环境因素（如天气、行为状态、亚群大小和组成）如何影响野生黑白毛吼猴不同叫声类型的发声活动。我们于 2019 年 5 月至 8 月在芒戈沃（Ranomafana 国家公园）对 31 只个体（两个群体）进行了焦点跟随，以记录行为和发声活动。我们区分了 11 种叫声类型，尽管其中三种（哼声、咆哮声、喋喋声）构成了大部分的发声活动。叫声频率全天保持一致，但在降雨量较大时会降低。我们发现叫声的使用存在性别和亚群特异性差异，这可能与雌性的主导地位和亚群组成有关。我们确定了一些叫声类型在特定行为背景下持续出现的情况；这可以帮助推断叫声的功能。本研究提供了一些关于毛吼猴声音交流的首次定量分析，并为未来研究中更系统的假设检验奠定了基础。
