Female dark‐eyed juncos Junco hyemalis thurberi produce male‐like song in a territorial context during the early breeding season

Abstract

Reports of female song, once considered a rarity, have recently increased across a variety of avian taxa. Females of many species can be induced to produce male-like song with exogenous testosterone, but observations of female song in free-living birds remain limited by incomplete sampling of females. Here, we report three independent observations of female dark-eyed juncos Junco hyemalis producing male-like song early in the breeding season (i.e. post-territory establishment, pre-nesting) in a recently established non-migratory, urban population. To elicit song, we presented 17 free-living junco pairs with a live, caged female conspecific. Three unique females responded to our trials by diving at the intruding female, chasing their (male) mate, fanning their tail feathers, and singing a trilled song similar in structure to male long-range (broadcast) song. We compared male and female songs quantitatively and found that the two sexes were statistically similar in many spectral and temporal characteristics, but female songs had significantly lower minimum and peak frequencies than males. This result is particularly surprising, as males in this urban population are known to sing at a significantly higher minimum frequency than males in a nearby montane population. Both the seasonal and social context in which these songs were observed suggest a potential function for female song in mate guarding and polygyny prevention, but more data are needed to test this hypothesis. Whether female song is common in all dark-eyed juncos during the early breeding season or if it is restricted to this particular urban and non-migratory population remains an important question for future research.

Female song in the Cyprus Wheatear Oenanthe cypriaca

“…Female song predominantly occurred during April, suggesting that females might compete for territories or partners on arrival from migration, and may also announce their fertility to males (Langmore 1998) observations of female-female aggression coincident with singing suggest that at least one function of female song in this species is for territorial defence and this has been observed in a few other species (e.g. Reichard et al 2018;Kirschel et al 2020), and two further observations of female song occurred when two males were present suggesting that it may be involved in signalling fertility, mate choice (Langmore 1998), or pair bonding (Sethi and Bhatt 2012).…”

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

“…Female European starlings (Sturnus vulgaris) produced song during aggression directed towards caged females placed in their territory (Sandell and Smith 1997). Dark-eyed junco (Junco hyemalis) females sang while showing aggressive behaviour towards the presentation of caged females (Reichard et al 2018). In barn swallows (Hirundo rustica) females used song to interrupt male song, potentially disrupting mate attraction by the male (Wilkins et al 2020), and in eastern whipbirds (Psophodes olivaceus) females approached more closely to playback of female solo song than to male or duet songs (Rogers et al 2007).…”

“…With this shifting view, new questions arise regarding the function of female song and the selection pressures underlying sexual differences. Even though the study of female song lacks the literature background of male song, the evidence indicates that it can serve similar functions such as territory advertisement (Cain et al 2015;Cooney and Cockburn 1995), mate attraction (Langmore et al 1996), mate guarding (Reichard et al 2018) or resource defence (Tobias and Seddon 2009). One of the most common roles of female song, regarding non-duetting species, is related to the competition for breeding resources (and mates) between females (Austin et al 2021;Langmore 1998).…”

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).…”