Female song is widespread and ancestral in songbirds

Abstract

Bird song has historically been considered an almost exclusively male trait, an observation fundamental to the formulation of Darwin's theory of sexual selection. Like other male ornaments, song is used by male songbirds to attract females and compete with rivals. Thus, bird song has become a textbook example of the power of sexual selection to lead to extreme neurological and behavioural sex differences. Here we present an extensive survey and ancestral state reconstruction of female song across songbirds showing that female song is present in 71% of surveyed species including 32 families, and that females sang in the common ancestor of modern songbirds. Our results reverse classical assumptions about the evolution of song and sex differences in birds. The challenge now is to identify whether sexual selection alone or broader processes, such as social or natural selection, best explain the evolution of elaborate traits in both sexes.

Is sexual dimorphism in singing behavior related to syringeal muscle composition?

“…Song production by both sexes is thought to be ancestral (Odom et al 2014), and female song is more common in tropical species (Slater and Mann 2004). Most females possess complex call repertoires; the female Streak-backed Oriole (Icterus pustulatus) sings more than the male (Price et al 2008).…”

Female in-nest chatter song increases predation

“…(4) Both sexes should vocalize away from the nest to reduce predation risk from nest conspicuousness. (5) At artificial nests at which we broadcast female song, we predict higher egg predation when there is a higher rate of song. Prediction (1) could predict either a low song rate at later stages or (4) that both sexes will sing away from the nest.…”

“…However, there is growing focus on the occurrence [3] and functions of female song [4], mostly using the perspective of life history and social selection theory. Female song is widespread and ancestral in songbirds, and females sing across 71% of extant species spanning 32 families [5]. Many Southern Hemisphere songbirds are sedentary, and females and their pair males sing solo song year-round to defend the territory [6,7].…”

Female Song in New World Wood-Warblers (Parulidae)

“…Much recent work has corrected this bias and found that while male song is certainly more common in some geographical regions, female song is widespread among songbirds (Odom et al, 2014) and can have important functions in many (if not all) of the same contexts as male song: defense of a territory, mate attraction, maintenance of the pair bond, and mate guarding (Hall, 2004;Slater and Mann, 2004).…”

“…In addition to understanding the functions of female song, researchers are interested in the evolutionary history, and ecological correlates of female song (Price, 2009;Odom et al, 2014). Observers have long noted that female song is more common in tropical and sub-tropical areas than it is in temperate regions (Slater and Mann, 2004).…”