Large female song repertoires and within‐pair song type sharing in a temperate breeding songbird

Abstract

Female song has been significantly understudied in songbirds. While male song has been studied for centuries, female song has only begun to be explored in the last few decades. This is especially true in relation to understanding repertoire size and function. In male songbirds, song repertoires are thought to function primarily in mate attraction and territory defense. Only a few studies to date have explored repertoire size in female songbirds, and many of those focused on tropical duetting species. We quantified the size and explored the function of song repertoires in a temperate breeding songbird, the eastern bluebird. Female song in eastern bluebirds functions primarily in communication with a social mate in order to maintain long-term pair bonds. Previous work in this species also documented that males have large repertoires serving a variety of purposes. We found that female bluebirds have similar song repertoire sizes to males. Also, females share their repertoires and song types more closely with their mate than shared with non-mates. This is one of the first studies to document large female repertoires in a non-duetting temperate species. Our findings indicate that large female repertoires and song type sharing in this species is integral to communication between social mates. Additionally, the large effect size of song type sharing with newly formed mates suggests open-ended learning may be present in this songbird, a previously under-documented phenomenon in females. This study provides the groundwork to explore the ontogeny and evolution of song repertoire size in female songbirds and to expand our understanding of song repertoires beyond their functions in males as an indicator of male fitness.

The singing question: re‐conceptualizing birdsong

“…Due to these inconsistent definitions, the vocalizations that are included or excluded from the ‘complex/song’ category may differ by study. For example, if a definition of complexity focuses on amplitude (loudness) as the most important feature, then the large repertoires of female eastern bluebirds would be excluded (Spector, 1994; Sikora et al ., 2020). Interestingly, regardless of definition there are a few species whose songs are not considered complex (Spector, 1994).…”

Sexual and temporal variation in New Zealand bellbird song repertoires

“…Female song has also been linked to reproductive success, for example, higher singing rates towards territorial intruders (Cain et al, 2015), spontaneous female song and song complexity (Brunton et al, 2016) are positively correlated with the number of fledglings females’ produce. Female song may also function in within-pair communication (Rose et al, 2020; Sikora et al, 2021). These studies suggest that different aspects of female song repertoires may be driven by either (or both) intra-sexual and inter-sexual selection pressures.…”

An Investigation of the Song Complexity of Toutouwai (Petroica longipes)

“…Commonly, song is studied to understand male genetic fitness, as it is assumed that those males with more complex songs are more likely to attract a mate as well as maintain the best territories (Sikora et al 2020). The sexual selection hypothesis states that females will choose a mate with a larger song repertoire compared to an individual with a smaller song repertoire (Najar and Benedict, 2019).…”