ABSTRACT: Eavesdropping, the detection of communication signals by unintended receivers, can be beneficial in predator-prey interactions, competition, and cooperation. The cosmopolitan killer whale Orcinus orca has diverged into several ecotypes which exhibit specialised diets and different vocal behaviours. These ecotypes have diverse ecological relationships with other marine mammal species, and sound could be a reliable sensory modality for eavesdroppers to discriminate between ecotypes and thereby respond adaptively. Here, we tested whether humpback whales Megaptera novaeangliae in the Northeast Atlantic responded differently to playback of the sounds of 2 killer whale ecotypes, Northeast Atlantic herring-feeding killer whales representing food competitors and Northeast Pacific mammal-eating killer whales simulating potential predators. We used animal-borne tags and surface visual observations to monitor the behaviour of humpback whales throughout the playback experiments. Humpback whales clearly approached the source of herring-feeding killer whale sounds (5 of 6 cases), suggesting a ‘dinner-bell’ attraction effect. Responses to mammal-eating killer whale sounds varied with the context of presentation: playback elicited strong avoidance responses by humpback whales in offshore waters during summer (7 of 8 cases), whereas the whales either approached (2 of 4 cases) or avoided (2 of 4 cases) the sound source in inshore waters during winter. These results indicate that humpback whales may be able to functionally discriminate between the sounds of different killer whale ecotypes. Acoustic discrimination of heterospecific sounds may be widespread among marine mammals, suggesting that marine mammals could rely on eavesdropping as a primary source of information to make decisions during heterospecific encounters.

中文翻译：

---

表明座头鲸对虎鲸声音的行为反应受营养关系影响

摘要：窃听，即意外接收者对通信信号的检测，可能对捕食者与猎物的互动，竞争与合作很有帮助。大都会虎鲸Orcinus orca已分化成几种生态类型，表现出专门的饮食和不同的声音行为。这些生态型与其他海洋哺乳动物物种具有不同的生态关系，声音可能是窃听者辨别生态型并从而做出自适应反应的可靠感觉方式。在这里，我们测试了座头鲸是否为Megaptera novaeangliae在东北大西洋，两种回放方式的虎鲸对声音的反应不同，代表食物竞争者的东北大西洋以鲱鱼为食的虎鲸和模拟潜在捕食者的东北太平洋以哺乳动物为食的虎鲸。在整个播放实验中，我们使用了动物传播的标签和表面视觉观察来监视座头鲸的行为。座头鲸显然接近了以鲱鱼为食的虎鲸的声音来源（6例中的5例），表明有“晚餐铃”的吸引作用。对吃食虎鲸的声音的响应随呈现方式的不同而变化：夏季，回放引起座头鲸强烈回避反应（8例中的7例），而鲸鱼则在冬季接近（4个案例中的2个）或避开（4个案例中的2个）声源。这些结果表明座头鲸可能能够在功能上区分不同虎鲸生态型的声音。对异种声音的声学辨别可能在海洋哺乳动物中广泛存在，这表明海洋哺乳动物可以依靠窃听作为信息的主要来源，从而在异种遭遇中做出决定。