9Introductory gestures are present at the beginning of many animal displays. For example, lizards start 10 their head-bobbing displays with introductory push-ups and animal vocal displays begin with 11 introductory notes. Songbirds also begin their vocal displays by repeating introductory notes (INs) 12 before producing their learned song and these INs are thought to reflect motor preparation. Between 13 individuals of a given species, the acoustic structure of INs and the number of times INs are repeated 14 before song varies considerably. While similar variation in songs between individuals is known to be a 15 result of learning, whether INs are also learned remains poorly understood. Here, using natural and 16 experimental tutoring with male zebra finches, we show that mean IN number and IN acoustic structure 17 are learned from a tutor, independent of song learning. We also reveal biological predispositions in IN 18 production; birds artificially tutored with songs lacking INs still repeated a short-duration syllable, 19 thrice on average, before their songs. Overall, these results show that INs, just like elements in song, 20 are shaped both by learning and biological predispositions and suggest multiple, independent, learning 21 processes underlying the acquisition of complex vocal displays. 22

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 variations 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, were 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.