Individual or group signatures in spotted hyena whoops

In animal societies, identity signals mediate interactions within groups, and allow individuals to discriminate group-mates from out-group competitors. However, individual recognition becomes increasingly challenging as group size increases and as signals must be transmitted over greater distances. Group vocal signatures appear to evolve when successful in-group/out-group distinctions are at the crux of fitness-relevant decisions, but individual-based recognition systems may be favored when differentiated within-group relationships are important for decision-making. Spotted hyenas are social carnivores that live in stable clans of <125 individuals composed of multiple unrelated matrilines. Clan members cooperate to defend resources and communal territories from neighboring clans and other mega carnivores; this collective defense is mediated by long-range (up to 5 km range) recruitment vocalizations, called whoops. Here, we use machine learning to determine that spotted hyena whoops c...在动物社会中，身份识别信号调控群体内的互动行为，使个体能够区分同群同伴与外来竞争者。然而，随着群体规模扩大，且信号需传递至更远距离，个体识别的难度会持续攀升。当成功区分群内与群外个体是关乎个体适合度的决策核心时，群体声音特征信号便可能演化形成；而当群体内部的差异化社会关系对决策至关重要时，基于个体的识别系统则更受青睐。斑鬣狗（spotted hyena）是群居食肉动物，栖息于由多个无亲缘关系母系群构成、个体数量不足125只的稳定族群（clan）中。族群成员会协同防御资源与公共领地，抵御邻近族群及其他大型食肉动物的侵扰；这类集体防御行为依托于传播距离可达5公里的远距离招募鸣叫声，即嚎鸣（whoops）。在此，我们通过机器学习方法证实，斑鬣狗的嚎鸣可……