Introductory gestures before songbird vocal displays are shaped by learning and biological predispositions

Numerous animal displays begin with introductory gestures. For example, lizards start their head-bobbing displays with introductory push-ups and many songbirds begin their vocal displays by repeating introductory notes (INs) before producing their learned song. Among songbirds, the acoustic structure and the number of INs produced before song vary considerably between individuals in a species. While similar variation in songs between individuals is a result of learning, whether variation in INs are also due to learning remains poorly understood. Here, using natural and experimental tutoring with male zebra finches, we show that mean IN number and IN acoustic structure are learned from a tutor. Interestingly, IN properties and how well INs were learned, was not correlated with the accuracy of song imitation and only weakly correlated with some features of songs that followed. Finally, birds artificially tutored with songs lacking INs still repeated vocalizations that resembled INs, before their songs, suggesting biological predispositions in IN production. These results demonstrate that INs, just like song elements, are shaped both by learning and biological predispositions. More generally, our results suggest mechanisms for generating variation in introductory gestures between individuals while still maintaining the species-specific structure of complex displays like birdsong.

Methods
All of the songs used in this study were collected in the undirected condition (i.e. when no other bird was present). 

Data_ProceedingsB_RSPB-2020-2796.zip contains data and matlab script files for generating all of the main and supplementary figures. Data are in the form of .mat files that contain all of the necessary variables related to the analysis. In addition, for each bird we have included text files that provide details for all song bouts used for analysis. Specifically, these files have onset and offset times, and syllable identity labels for all syllables. 

We have provided a detailed ReadMe that describes usage of scripts and provides details of data.