Table_4_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.

翼手目（Chiroptera）蝙蝠拥有适配多类应用场景的精细声学能力，涵盖回声定位（echolocation）与社交发声（social vocalisations）两大范畴。社交发声的应用场景广泛，其声学排布与复杂度差异悬殊。其中结构最为繁复的鸣曲类型，是部分物种雄性个体用以吸引配偶、彰显自身特质的求偶鸣曲（courtship songs）。截至目前，鲜有研究探讨蝙蝠鸣曲的语音结构（phonological construction），亦未对组合不同鸣曲元素所采用的句法规则开展细致评估。本研究聚焦新西兰短尾蝙蝠（Mystacina tuberculata）的求偶鸣曲句法结构——该物种为高发声频次、依赖求偶场繁殖（lek-breeding）的高鸣唱输出类群。我们提出假说，认为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，这可能使其具备个体识别的潜力。我们录制了9只雄性蝙蝠的求偶鸣曲，通过人工分类鸣曲组件以解析鸣曲结构。本研究旨在探究不同鸣曲组件的使用是否与其位置相关，并明确不同组件间的转移概率。研究结果显示，无论在个体还是种群层面，鸣曲元素的产生频次与元素在鸣曲中的分布均呈现非随机性，且个体间每乐句（phrase）所使用的元素数量存在差异。整体而言，我们证实新西兰短尾蝙蝠的鸣曲为层级化构建，并通过语音句法（phonological syntax）组合形成音节（syllables）与乐句。本研究进一步表明，蝙蝠在音节构建中展现出较高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，且大概率支持个体识别功能。