How do some species maintain both individual signature signals and shared group signals at the same time?

How can a call be both personal and shared?

A contact call can carry individual identity while still doing a group job. In pallid bats, the frequency pattern of contact calls is highly repeatable within an individual over time but differs significantly among individuals, making the call well-suited for roostmate recognition [1]. At the same time, these calls attract other bats and elicit approaches, especially when the caller is familiar, so the same signal helps maintain group cohesion [1].

This works because the call's structure encodes identity in a way that listeners can use, while its function—attracting roostmates—is shared across the group. The call is not a group anthem that erases individuality; it is a personal signature that also serves a collective purpose.

What happens when animals copy each other's signature calls?

Bottlenose dolphins provide another route: they imitate each other's signature whistles. These whistles identify individuals, and copying them allows dolphins to use vocal matching in interactions, effectively sharing an individual's signal within the group [3]. The imitation occurred in both captive and wild animals, suggesting that copying is a natural part of their vocal behavior [3].

In this case, the individual signature is not replaced by a group signal; instead, the group temporarily adopts or echoes an individual's signature. This blurs the line between individual and shared signals, showing that sharing can happen through learning and imitation rather than through a fixed group-specific call.

Does social structure affect the balance between individual and group signals?

Social structure can influence how vocal signatures are expressed. In resident killer whales, individual signatures are often present, while animals that are part of a group may benefit more from sharing vocalizations [2]. This suggests that the balance between individual distinctiveness and group sharing is not fixed but can shift with social organization.

The evidence from killer whales is limited to what the abstract reports, but it points to a general principle: the same species can maintain individual signatures alongside group-specific features, and the social context helps determine which aspects are emphasized.

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