Table_3_Syntactic properties of male courtship song in the lesser short-tailed bat, Mystacina tuberculata.XLSX

Bats (Mammalia: Chiroptera) have sophisticated acoustic abilities adapted to many uses, including both echolocation and social vocalisations. Social vocalisations are used in a wide variety of contexts and vary greatly in acoustic arrangement and complexity. Among the most intricate are the courtship songs that males of certain species use to attract mates and advertise their qualities. To date, however, few studies have examined the phonological construction of bat songs or made a detailed assessment of the syntax used to combine different song elements. Here, we examine the syntactic construction of courtship songs in the New Zealand lesser short-tailed bat, Mystacina tuberculata, a highly vocal, lek-breeding species with exceptionally high song-output rates. We hypothesised that song construction in this species is both hierarchical and non-random, and demonstrates a high degree of individual variation, potentially allowing for individual recognition. We recorded the courtship songs of nine male bats and used manual classification of song components to examine the song structure. Here we examine whether the deployment of different song components is dependent on their position, and also determine the transition probabilities between different components. We find that the frequency of song-element production and the distribution of elements within songs are non-random at both the individual and population level, and that the number of elements used per phrase differs between individuals. Overall, we demonstrate that M. tuberculata songs are hierarchically constructed and employ phonological syntax to build syllables and phrases. We further show that bats employ high structural similarity and conservatism in the construction of syllables, while retaining a capacity for versatility and innovation that allows for considerable individual variation and, likely, individual recognition.

蝙蝠（哺乳纲：翼手目，Mammalia: Chiroptera）具备适配多场景应用的精密声学能力，涵盖回声定位（echolocation）与社交发声（social vocalisations）两大类别。社交发声的应用场景极为广泛，其声学排布模式与复杂程度亦存在显著差异。其中，部分物种雄性个体用于吸引配偶、彰显自身特质的求偶鸣曲（courtship songs），便是此类发声中最为精巧的类型之一。
然而截至目前，鲜有研究针对蝙蝠鸣曲的语音结构（phonological construction）展开探讨，亦未对用于组合不同鸣曲元素的句法开展细致评估。本研究以新西兰小短尾蝙蝠（Mystacina tuberculata）为研究对象，解析其求偶鸣曲的句法构建模式；该物种为高发声性、依赖求偶场繁殖的物种，且鸣唱产出率极高。
我们提出研究假说：该物种的鸣曲构建兼具层级性与非随机性，且个体差异显著，这一特征或可支持个体识别。我们录制了9只雄性蝙蝠的求偶鸣曲，并通过人工分类鸣曲组分以解析鸣曲结构。本研究旨在探究不同鸣曲组分的使用是否与其所处位置相关，并明确不同组分间的转移概率。
研究结果表明，无论是在个体层面还是种群层面，鸣曲元素的产出频率与元素在鸣曲中的分布均呈现非随机特征；且不同个体每鸣曲短语（phrase）所使用的元素数量存在显著差异。
总体而言，本研究证实M. tuberculata的鸣曲为层级式构建，并通过语音句法（phonological syntax）组合音节与鸣曲短语。进一步分析显示，蝙蝠在音节构建上具备高度的结构相似性与保守性，同时保留了灵活性与创新性，这使其能够产生显著的个体差异，进而大概率实现个体识别。