The effects of social separation, including vocalization, have been studied for a very long time in non-human primates under laboratory conditions. As part of the long-term research on the vocal behaviour of Nomascus gibbons in zoos, this study provides the first record of calls of the southern yellow-cheeked gibbon ( Nomascus gabriellae ) in response to involuntary separation. Our study revealed that calls were also emitted by an infant (aged 1 year 8 months), and that the acoustic structure of the infant’s calls was similar to that of older individuals’ calls. Separation-induced calls seem to have a shorter developmental convergence than vocalizations with a stable pattern (which are specific for species and sex). The acoustic structure of the calls reported here comprised simple syllables, and differed from the sex- and species-specific vocal patterns of this species. Our findings demonstrate a novel paradigm in this genus, and provide evidence of the ability of gibbons to express distress when socially separated.

中文翻译：

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第一份关于圈养南方黄颊长臂猿（Nomascus gabriellae）的分离呼叫报告

在实验室条件下，已经在非人类灵长类动物中研究了社会分离的影响，包括发声。作为对动物园长臂猿长臂猿发声行为长期研究的一部分，本研究首次记录了南方黄颊长臂猿（Nomascus gabriellae）对非自愿分离的反应。我们的研究表明，婴儿（1 岁 8 个月大）也会发出叫声，并且婴儿叫声的声学结构与老年人的叫声相似。与具有稳定模式的发声（特定于物种和性别）相比，分离引起的呼叫似乎具有更短的发育收敛。这里报告的呼叫的声学结构包括简单的音节，并且与该物种的性别和物种特定的声音模式不同。我们的研究结果证明了该属的一种新范式，并提供了长臂猿在社会分离时表达痛苦的能力的证据。