Age‐dependent song changes in a closed‐ended vocal learner: elevation of song performance after song crystallization

Abstract

Birdsong is a sexual signal that serves as an indicator of male quality. There is already abundant evidence that song elaboration reflects early life-history because early developmental stress affects neural development of song control systems, and leaves irreversible adverse effects on song phenotypes.Especially in closed-ended vocal learners, song features crystallized early in life are less subject to changes in adulthood. This is why less attention has been paid to lifelong song changes in closed-ended learners. However, in the eyes of female birds that gain benefits from choosing mates based on male songs, not only past but also current conditions encoded in songs would be meaningful, given that even crystallized songs in closed-ended learners would not be identical in the long term. In this study, we examine within-individual song changes in the Java sparrow Lonchura oryzivora, with the aim of shedding light on the relationship between song and long-term life history. Specifically, we compared song length, tempo, and song complexity measures between the point just after song crystallization and around 1 year later, and also compared those traits between fathers and sons to clarify the effect of vocal learning. While it is not surprising that song complexity did not differ depending on age or between fathers and sons, we found that song length and tempo increased with age. Follow-up analyses have revealed that frequency bandwidth and peak frequency of song notes also elevated with age. Our results show that song performance related to motor skills can be improved even after song crystallization. We also suggest that song performance in closed-ended vocal learners gives a reliable clue for mate choice by reflecting male quality with aging.

Evolution of courtship display in Estrildid finches: dance in relation to female song and plumage ornamentation

“…However, it remains unclear why some female Estrildid finches sing as surprisingly little is known about vocal communication in this taxonomic group. In contrast with a few limited Estrildid species without females song (e.g., Zebra and Bengalese finches) that have been well studied, singing behaviors of males and females of the rest of the species are largely uncertain (but see Gahr and Güttinger, 1986;Gahr, 2011, 2013;Kagawa and Soma, 2013;Ota and Soma, 2014), and can be a crucial key to understand the evolution of multimodal communication in future studies.…”

Mating success follows duet dancing in the Java sparrow

“…Java sparrows tended to start singing by producing sparse repetition of introductory notes before the main song (Fig 1A; cf. [36]), similar to the behaviour reported in a closely related species, the Bengalese finch [37]. Presence of songs was scored as follows: 0, male produced no song during the courting phase; 1, male produced introductory notes but not the main song during the courting phase; 2, male produced at least part of the main song during the courting phase.…”

The Songbird as a Percussionist: Syntactic Rules for Non-Vocal Sound and Song Production in Java Sparrows

“…Male Java sparrows sing one song type that they learn from their social fathers [ 21 ]. The songs are characterized by their note-type repertoire and the ordering of stereotyped notes [ 22 , 23 ], and often involve bill clicks. To best compare song learning and bill clicks, birds that failed to copy the full note repertoire of their fathers (n = 3) were not used as subjects in this study.…”