Vocal communication has been extensively studied and there is wide evidence that it plays a vital role for individual survival and reproduction in many animal species. In songbirds, most studies to date have focused mainly on the conspicuous song, often disregarding calls even though these seem to be almost omnipresent in some species. Until now, it proved challenging to obtain reliable individual-level vocalisation recordings from interacting animals, especially if those were at close range, and often involved strongly reduced environments.

In our study, we aimed to investigate the role of different calls in naturally occurring interactions of zebra finches (Taeniopygia guttata) during different stages of the breeding cycle, by gaining long-term vocalisation recordings from individuals behaving freely in groups in a changing social and abiotic environment. Accordingly, male and female zebra finches previously unknown to each other were fitted with audio transmitters, placed in large aviaries and provided with nest material. In combination with behavioural observations, breeding success and hormone data, our results suggest that the birds, when passing through different hormone-related breeding stages, modified their vocal behaviour on the individual, pair and group level through changes in call-type repertoire and vocal interaction patterns. In addition, we offer evidence that calling interactions between mates may be related to pair breeding success, thus highlighting the importance of calls in communication systems.