Dolphins have a diverse acoustic communication system which includes whistles necessary for their survival. Whistle variation in dolphins could be related to the group behaviour, group size, formation and also environmental factors such as water depth, tidal phases and location. Such information is relatively unknown for the dolphin populations in Malaysia. This study aims to understand the whistle variation in Indo-Pacific humpback dolphins found in two sites in northwestern Peninsular Malaysia and possible factors that influence their whistles. A total of 4971 whistles were detected with whistle rates and parameters analysed. A GLMM analysis showed that whistle rates in both sites and in differing group sizes had significant differences. Only the mean whistle frequency significantly differed in differing group formations. Indo-Pacific humpback dolphins in a loose and uniform group had a lower mean frequency compared to other group formations. Other parameters such as the whistle duration and coefficient of frequency modulation did not show significant differences in differing behaviour, size, formation, water depth, tidal phases and location. This study is important and particularly valuable for understanding the species’ bioacoustics in the wider region of Southeast Asia.

海豚拥有多样化的声学通信系统，其中包括它们生存所必需的口哨声。海豚的哨声变化可能与群体行为、群体规模、形成以及水深、潮位和位置等环境因素有关。对于马来西亚的海豚种群，此类信息相对未知。本研究旨在了解在马来西亚半岛西北部的两个地点发现的印度太平洋驼背海豚的哨声变化以及影响其哨声的可能因素。共检测到 4971 个哨子，并分析了哨声率和参数。GLMM 分析表明，两个站点和不同群体规模的哨声率存在显着差异。只有平均哨声频率在不同的组队中显着不同。与其他组群相比，松散和均匀组中的印度太平洋驼背海豚的平均频率较低。其他参数，例如哨声持续时间和频率调制系数，在不同的行为、大小、地层、水深、潮位和位置方面没有显示出显着差异。这项研究对于了解东南亚更广泛地区的物种生物声学非常重要且特别有价值。