Sounds are particularly important for animals that live in complex social communities. In this study, we assessed the communication calls (whistles) that common bottlenose dolphins emit during their foraging activities in the absence and presence of motor boats and during dolphin depredation on trawlers, in Alghero (Sardinia, Italy) and Cres-Lošinj Archipelago (Croatia). The latter behaviour involves foraging on concentrated food sources during very noisy human activity and may require the emission of distinctive whistles. Thus, we investigated if whistle structure, in terms of frequency and time parameters, changes depending on these three foraging contexts. In Sardinia, during foraging in interaction with trawlers, whistles differed from those emitted during the other foraging contexts. Conversely, in Cres-Lošinj, significant variations in whistles were found to be related mainly to the presence of motor boats. This study represents the first report on how two dolphin populations adopt different acoustic tactics in the context of similar foraging behaviour. By investigating the effects of opportunistic foraging on acoustic repertoires, we provide new findings on the acoustic adaptation of dolphins to local conditions and contribute to understanding the relationships between dolphins and human activities, such as fishing and boat traffic.

中文翻译：

---

觅食环境对普通宽吻海豚哨声结构的影响

声音对于生活在复杂社会社区中的动物尤其重要。在这项研究中，我们评估了在阿尔盖罗（意大利撒丁岛）和 Cres-Lošinj 群岛（克罗地亚），在没有和有摩托艇的情况下，以及在拖网渔船上捕食海豚期间，普通宽吻海豚在觅食活动期间发出的通信叫声（哨声） ）。后一种行为涉及在非常嘈杂的人类活动中觅食集中的食物来源，并且可能需要发出独特的口哨声。因此，我们研究了哨子结构在频率和时间参数方面是否会根据这三种觅食环境而变化。在撒丁岛，在与拖网渔船互动的觅食过程中，哨声与其他觅食环境中发出的哨声不同。相反，在 Cres-Lošinj，发现哨声的显着变化主要与摩托艇的存在有关。这项研究是关于两个海豚种群如何在类似觅食行为的背景下采用不同声学策略的第一份报告。通过研究机会性觅食对声学曲目的影响，我们提供了关于海豚对当地条件的声学适应的新发现，并有助于了解海豚与人类活动（如捕鱼和船只交通）之间的关系。