Mismatch in sexual dimorphism of developing song and song control system in blue-capped cordon-bleus, a songbird species with singing females and males

Abstract

Brain song control regions of adult passerine birds are sexually dimorphic in species such as the zebra finch (Taeniopygia guttata) in which males sing whereas females do not. In many tropical bird species, however, females sing as well. Here we study for the first time the ontogeny of the song control system and the song in a species in which both male and female sing regularly. In blue-capped cordon-bleus (Uraeginthus cyanocephalus), a distant relative of the zebra finch, both males and females start singing at around 30-40 day post-hatching (dph). First we quantified that sex-specific differences in song features emerged only in adulthood, after 250 dph of age: Adult females sang complex songs, which were slightly shorter and contained fewer syllables as compared to the males. Second, the development of forebrain song control regions HVC (proper name) and RA (nucleus robustus arcopallii) of blue-capped cordon-bleus was quantified in both sexes at 20, 30, 50, 100, 150, 250 dph as well as in old adults. The volume and neuron numbers of the HVC and RA were sexually dimorphic throughout the entire development and remained sexually dimorphic in adulthood. Since singing developed in a non sex-specific way until 250 dph, neural sex differences to a large extent precede the behaviorally (song) sex differences. This suggests that these neuroanatomical sex differences are not causally related to the sexual differentiation of song patterns in this species.

Superb Fairy-Wren (Malurus cyaneus) Sons and Daughters Acquire Song Elements of Mothers and Social Fathers

“…Males may have a longer sensory acquisition phase than females and acquire more element types over a longer timeframe, which is another explanation for why adult males have more complex song than females. Such a process has been proposed for Northern cardinals and bluecapped cordon-bleus (Yamaguchi, 2001;Geberzahn and Gahr, 2013;Lobato et al, 2015). All we can say at present is that we found no sex differences in fledgling song element repertoire, so therefore it is likely that sex differences emerge later in the superb fairy-wren.…”

“…It is possible that daughters lose element types with age, as we did not find sex differences in fledgling element repertoire size. Such a decrease in repertoire size with age has been found in female blue-capped cordon-bleus (Lobato et al, 2015). Males may have a longer sensory acquisition phase than females and acquire more element types over a longer timeframe, which is another explanation for why adult males have more complex song than females.…”

“…Studies on captive birds show that young male and female songbirds learn primarily from same-sex vocal tutors in slate-colored boubous (Laniarius funebris; Wickler and Sonnenschein, 1989), stripebacked wrens (Campylorhynchus nuchalis; Price, 1998), and European starlings (Sturnus vulgaris; Hausberger et al, 1995). Young birds learn from both male and female song tutors in Indian Hill mynahs (Gracula religiosa; Bertram, 1970), Northern cardinals (Cardinalis cardinalis; Yamaguchi, 2001) and bluecapped cordon-bleus (Uraeginthus cyanocephalus; Geberzahn and Gahr, 2013;Lobato et al, 2015).…”

Audition and Hemispheric Specialization in Songbirds and New Evidence from Australian Magpies

“…This correlation, so they show, accounts for almost half of the observed variation in telencephalic size, more than any other behavioral specialization examined, including the ability to learn song. Moreover, female song is widespread and ancestral in birds [38][39][40][41]. In other words, as was recognized some time ago, relying on the zebra finch model in terms of broader questions of behavior could lead to ignoring the importance of social learning in non-reproductive contexts [42,43], the significance of variability in avian communication outside the breeding context and the possibility of different underlying mechanisms of brain activity [44][45][46] for hearing and vocal production, of which lateralization may be an important manifestation.…”

Identificação neuroanatômica de áreas cerebrais relacionadas à produção do canto em uma espécie de pássaro Suboscine da Amazônia (Myiozetetes cayanensis)

“…A via motora foi descrita no estudo inaugural de BOTTJER et al, 1985;WILLIAMS, 1985;NORDEEN e NORDEEN, 1988;NIXDORF-BERGWEILER, 1996;CAREW, 2000;LOBATO et al, 2015).…”