Statistical learning for vocal sequence acquisition in a songbird

Logan S. James,Herie Sun,Jon T. Sakata,Kazuhiro Wada

doi:10.1038/s41598-020-58983-8

Abstract

Birdsong is a learned communicative behavior that consists of discrete acoustic elements (“syllables”) that are sequenced in a controlled manner. While the learning of the acoustic structure of syllables has been extensively studied, relatively little is known about sequence learning in songbirds. Statistical learning could contribute to the acquisition of vocal sequences, and we investigated the nature and extent of sequence learning at various levels of song organization in the Bengalese finch, Lonchura striata var. domestica. We found that, under semi-natural conditions, pupils (sons) significantly reproduced the sequence statistics of their tutor’s (father’s) songs at multiple levels of organization (e.g., syllable repertoire, prevalence, and transitions). For example, the probability of syllable transitions at “branch points” (relatively complex sequences that are followed by multiple types of transitions) were significantly correlated between the songs of tutors and pupils. We confirmed the contribution of learning to sequence similarities between fathers and sons by experimentally tutoring juvenile Bengalese finches with the songs of unrelated tutors. We also discovered that the extent and fidelity of sequence similarities between tutors and pupils were significantly predicted by the prevalence of sequences in the tutor’s song and that distinct types of sequence modifications (e.g., syllable additions or deletions) followed distinct patterns. Taken together, these data provide compelling support for the role of statistical learning in vocal production learning and identify factors that could modulate the extent of vocal sequence learning.

Highlights

Birdsong is a learned communicative behavior that consists of discrete acoustic elements (“syllables”) that are sequenced in a controlled manner
We examine sequence similarities across the songs of tutors and their pupils at various levels of song organization to assess the nature and extent of vocal sequence learning in Bengalese finches
In contrast to the learning of the acoustic structure of individual elements, relatively little is known about the acquisition of sequences of acoustic elements, especially for animals with complex sequence structures that resemble those observed in human language

Summary

Introduction

Birdsong is a learned communicative behavior that consists of discrete acoustic elements (“syllables”) that are sequenced in a controlled manner. We discovered that the extent and fidelity of sequence similarities between tutors and pupils were significantly predicted by the prevalence of sequences in the tutor’s song and that distinct types of sequence modifications (e.g., syllable additions or deletions) followed distinct patterns Taken together, these data provide compelling support for the role of statistical learning in vocal production learning and identify factors that could modulate the extent of vocal sequence learning. Songbirds are a valuable model system to study statistical learning in the context of vocal production learning[24,25] Songbirds learn their communication signals (“songs”) during development, and their songs consist of acoustic elements (“syllables”) that are arranged in various types of sequences, ranging from stereotyped and linear sequences (e.g., white-crowned sparrows, zebra finches) to more complex and variable sequences (e.g., nightingales, Bengalese finches)[26]. Little is known about the extent of vocal sequence learning at various levels of Bengalese finch song organization, about the nature of sequence deviations between tutors and pupils, or about factors that could influence the degree of sequence similarities between tutors and pupils

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