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

Abstract

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

CineFinch: An animated female zebra finch for studying courtship interactions

“…3B shows spectrograms of tutor song and songs of two juveniles; Fig. 3C; n=6 birds with video and n=10 birds with only audio playbacks from Kalra et al (Kalra et al, 2021)). These results suggested that the visual presence of an adult bird, albeit on a screen, does not improve copying accuracy and is supported by similar results from a recent study (Varkevisser et al, 2022a).…”

“…Songs were analysed as described earlier (Kalra et al, 2021; Rajan and Doupe, 2013; Rao et al, 2019), using custom-written scripts on MATLAB (MathWorks). Briefly, songs were first segmented into syllables based on an amplitude threshold.…”

“…The sequence of syllables that repeated in a bird’s song was identified as a motif (Sossinka and Böhner, 1980; Zann, 1996). Short syllables that were repeated a variable number of times at the beginning of a bout were considered as introductory notes (Kalra et al, 2021; Rajan, 2018; Rajan and Doupe, 2013; Rao et al, 2019). The number of introductory notes at the beginning of a bout was quantified by starting with the introductory note immediately preceding the first syllable of the bout and counting backwards until either (1) the previous note was not an introductory note or (2) there was a silence > 500 ms (Kalra et al, 2021; Kao et al, 2005; Rajan and Doupe, 2013; Rao et al, 2019; Sossinka and Böhner, 1980).…”

“…Short syllables that were repeated a variable number of times at the beginning of a bout were considered as introductory notes (Kalra et al, 2021; Rajan, 2018; Rajan and Doupe, 2013; Rao et al, 2019). The number of introductory notes at the beginning of a bout was quantified by starting with the introductory note immediately preceding the first syllable of the bout and counting backwards until either (1) the previous note was not an introductory note or (2) there was a silence > 500 ms (Kalra et al, 2021; Kao et al, 2005; Rajan and Doupe, 2013; Rao et al, 2019; Sossinka and Böhner, 1980). Song bouts were defined as groups of vocalizations that contained at least one motif syllable and were separated from other such groups by more than 2 s of silence.…”

“…Briefly, asymmetric time-course similarity measurements were made between tutor song and 5 example motifs and the average of these similarity values was taken as a measure of similarity to the tutor song. For comparison with birds tutored without videos, we used birds tutored at IISER Pune for a different study (n=10) (Kalra et al, 2021). These birds were tutored with 2 motifs without INs using active playback methods.…”