Data from: Vocal foragers and silent crowds: context-dependent vocal variation in Northeast Atlantic long-finned pilot whales

Vocalisations form a key component of the social interactions and foraging behaviour of toothed whales. We investigated changes in calling and echolocation behaviour of long-finned pilot whales between foraging and non-foraging periods, by combining acoustic recordings and diving depth data from tagged individuals with concurrent surface observations on social behaviour of their group. The pilot whales showed marked vocal variation, specific to foraging and social context. During periods of foraging, pilot whales showed more vocal activity than during non-foraging periods (rest, travel). In addition to the expected increase in echolocation activity, call rates also increased, suggesting that pilot whales communicate more during foraging. Furthermore, calls with multiple inflections occurred more often immediately before and after foraging dives and during the early descent and late ascent phases of foraging dives. However, these calls were almost never detected at diving depths of the tagged whale beyond 350 m. Calls with no or few inflections were produced at all times, irrespective of diving depth of the tagged whale. We discuss possible explanations for the distinct vocal variation associated with foraging periods. In addition, during non-foraging periods, the pilot whales were found to be more silent (no calling or echolocation) in larger, more closely spaced groups. This indicates that increased levels of social cohesion may release the need to stay in touch acoustically.发声是齿鲸（toothed whales）社会互动与觅食行为的核心组成部分。本研究结合佩戴追踪标记个体的声学录音与潜水深度数据，以及同步开展的鲸群社会行为水面观测，探究了长肢领航鲸（long-finned pilot whales）在觅食与非觅食时段的鸣叫与回声定位（echolocation）行为变化。 长肢领航鲸的发声存在显著差异，且与觅食及社会情境高度相关。觅食时段的发声活跃度显著高于非觅食时段（休息、巡游阶段）。除预期的回声定位活跃度提升外，鸣叫频次亦随之升高，表明长肢领航鲸在觅食期间的交流更为频繁。此外，带有多重声调变化的鸣叫更常出现在觅食潜水前后，以及觅食潜水的早期下潜与晚期上升阶段。但在标记个体潜水深度超过350米时，几乎未检测到此类鸣叫。而无或仅有少量声调变化的鸣叫则可在任意时段发出，不受标记个体潜水深度的影响。 本研究探讨了与觅食时段相关的显著发声差异的潜在成因。此外，研究发现在非觅食时段，当鲸群规模更大、个体间距更小时，长肢领航鲸会更为安静（无鸣叫或回声定位行为），这表明社会凝聚力的提升可能降低了个体间声学联络的需求。