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...