Vocal Cues to Identity: Pied Babblers Produce Individually Distinct But Not Stable Loud Calls

The ability to identify social partners can play a key role in the coordination of social behaviours in group-living animals. Coordinating social behaviours over long distances becomes problematic, as cues to identity are often limited to one or two sensory modalities. This limitation can often select for strong individuality in those cues used for long-distance communication. Pied babblers, Turdoides bicolor, produce a number of different types of 'loud calls' which are frequently used to signal to individuals beyond the range of visual or olfactory pathways of communication. Here, we show that three of these 'loud call' types, the v-shaped chatter, the double note ascending chatter and the atonal chatter, are each individually distinct. We hypothesise that individuality in the three loud call types tested here may represent a possible pathway to social recognition in this species that may have important consequences for social interactions. However, we also found that the atonal chatter was unstable between years suggesting that this particular call type may not be a reliable long-term indicator to identity which may affect long-term recognition in this species.