Sperm whales communicate using codas (stereotyped click sequences). Females and juveniles live in long-term social units, and units with similar coda repertoires share vocal clan membership. Vocal clans exhibit culturally defined differences in their multilevel social structure. Here, we aimed to identify different social units among sperm whales in Mauritius in the southwestern Indian Ocean, and to describe and compare their coda repertoires to investigate the presence of different vocal clans. We conducted six boat-based surveys between 2008 and 2013, during which 101 different individuals were photo-identified. Analysis of associations between 22 resighted individuals divided them into four candidate social units, but a lack of resightings impedes solid delineation of social units. Based on number and rhythm of clicks, at least 24 discrete coda types were detected among 4,767 analyzed codas using two different classification methods. Comparison of coda repertoires recorded from seven sperm whale groupings revealed the possible existence of two sympatric vocal clans, but the size differences of recorded repertoires warrant caution of interpretation. To further evaluate social structuring and the presence of different vocal clans in this region, future surveys should aim at obtaining long-term sighting and acoustic data, and cover a more extensive area.

中文翻译：

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印度洋西南部毛里求斯抹香鲸（Physeter macrocephalus）的声乐曲目和社会结构的见解

抹香鲸使用尾声（刻板的点击序列）进行交流。女性和青少年长期生活在社会单位中，具有相似尾声的单位共享声乐氏族成员资格。声乐氏族在其多层次的社会结构中表现出文化定义的差异。在这里，我们的目的是在印度洋西南部毛里求斯的抹香鲸中确定不同的社会单位，并描述和比较它们的尾声，以调查不同声带氏族的存在。我们在 2008 年至 2013 年期间进行了六次船基调查，在此期间对 101 名不同的人进行了照片识别。对 22 名有洞察力的个体之间关联的分析将他们分为四个候选社会单位，但缺乏洞察力阻碍了社会单位的明确划分。根据点击次数和节奏，使用两种不同的分类方法在 4,767 个分析的尾音中检测到至少 24 种离散尾音类型。对七个抹香鲸组记录的尾声曲目的比较揭示了可能存在两个同域声乐部族，但记录曲目的大小差异需要谨慎解释。为了进一步评估该地区的社会结构和不同声部的存在，未来的调查应着眼于获得长期的目击和声学数据，并覆盖更广泛的领域。