Frequent female song in blue tits: behavioural context suggests a role in intrasexual competition

Abstract

The blue tit (Cyanistes caeruleus) is an important avian model in evolutionary ecology (> 20,000 published scientific studies). Song, like in other songbird species, is generally described as a male trait and plays an important role in mate attraction and territory defence. Over the decades, there have been recurring reports of anecdotal female song but these have not led to any quantitative study of female song in blue tits. Our systematic sampling over three years revealed prolific female singing in a northern population of colour ringed blue tits. Daytime singing of females occurred throughout the breeding season during agonistic interactions, solo songs and alarm situations, and these contexts are similar to male song. Notably, female song was absent during the dawn chorus; the period around sunrise when males sing intensively just before mating. Female and male song overlapped substantially in acoustic structure (i.e. same song types, peak frequency or trill rates) but there were also significant differences in that females had smaller repertoires, shorter trills and lower vocal consistency. Differential selections pressures related with contextual (functional) differences in the role of male and female song could explain the observed differences in acoustic structure. The new finding of prolific female singing in such a well-studied species suggests we ought to revise our understanding of male and female vocal communication in this (and probably other) species. Identifying the selection pressures associated to the convergence versus divergence of male and female song may provide important insight in understanding birdsong evolution.

La voz de nuestras aves: contribuciones de la bioacústica a la ornitología colombiana

“…Por otro lado, la mayoría de las investigaciones sobre el canto de las aves se han realizado en zonas templadas del norte (Illes & Yunes-Jiménez 2009, Hahn et al 2013, Sierro et al 2021, en donde se supone que los machos tienen cantos más complejos o cantan con más frecuencia que las hembras (Rose et al 2018). Aunque existe un sesgo geográfico relacionado con la posición de los países del norte global en las zonas templadas del planeta y, una mayor cantidad de recursos destinados a las investigaciones científicas (Martin et al 2012, Soares et al 2022, los resultados de esas regiones pueden informar tendencias globales.…”

A Call to Expand Avian Vocal Development Research

“…Studies show that female song serves a critical function as a competitive trait among females to compete for reproductive resources (Langmore, 1998;Cain and Langmore, 2015;Brunton et al, 2016). Further, even for well-studied species in which females were not reported to sing, new research has shown that females simply sing less frequently, for shorter periods, or for different purposes (Reichard et al, 2018;Wilkins et al, 2020;Sierro et al, 2021), thus reducing the detectability of female song, especially in monomorphic species. However, almost nothing is known about female song learning and their development periods, whom they learn from, how they learn, or whether their development patterns are similar to males (Riebel et al, 2005;Evans and Kleindorfer, 2016;Roper et al, 2018).…”