Statistical learning for vocal sequence acquisition in a songbird

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.www.nature.com/scientificreports www.nature.com/scientificreports/ syllables. Some studies using experimental tutoring have confirmed the developmental acquisition of vocal sequencing 27-31 , but most of such studies have been conducted on species that produce stereotyped, relatively simple sequences of syllables (e.g., white-crowned sparrows and zebra finches) 26 . Understanding sequence learning in songbird species that produce more complex and variable sequencing is important not only for comparative reasons but also because such species produce syntactic structures that more closely resemble the complexity of syntax in human language 14 .The Bengalese finch (Lonchura striata var. domestica) offers an excellent opportunity to study the acquisition of relatively complex vocal sequences 32 . The songs of individual Bengalese finches consist of a discrete, learned repertoire of syllables that are arranged both in highly stereotyped sequences ("motifs" or "chunks") and in sequences that vary from rendition to rendition ("branch points"; Fig. 1) 26,[33][34][35][36][37][38][39][40] . Previous studies have provided some insight into vocal sequence learning in Bengalese finches by comparing songs between tutors and pupils 41-43 ; for example, Yamashita et al. (2008) analyzed the distribution of three-syllable sequences across two points in an individual's song development and...

Like Father Like Son: Cultural and Genetic Contributions to Song Inheritance in an Estrildid Finch

“…We also found evidence for cultural inheritance of song complexity, as measured by linearity (Scharff and Nottebohm, 1991), and of higher order note sequencing, as measured by differential entropy. Similar sequence learning has been reported recently in Bengalese finch, and birds were more likely to learn note transitions commonly used by their social fathers (James et al, 2020), although we did not examine this in our dataset.…”

The multi-dimensional nature of vocal learning

“…When birds learn a new song type, they have to acquire not only the elements that they need to produce but also the sequence and timing of these. There is also evidence that these two components are learned separately in songbirds, but that the processes are tightly integrated, similar to the processes that occur during human speech acquisition [134,[138][139][140]. Currently, it is unclear whether this type of sequence learning uses the same neural structures as when the bird learns to give a call in a new social context or whether it shares components used in vocal production learning.…”

Phylogeny and mechanisms of shared hierarchical patterns in birdsong

“…However, the motif phrases of house finches and common blackbirds tend to be more variable in sequencing from rendition to rendition, and given this variability in phrase composition, we analyzed the number and durations of syllables in each rendition of a motif in our recording. While Bengalese finches are known for their sequence variability, 64,65 sequence variation within Bengalese finch song centers around variation in sequencing between (and not within) motif phrases.…”