Song: The Learned Language of Three Major Bird Clades

Abstract

Vocal learning has evolved several times independently in mammals and three major orders of birds. Of these only hummingbirds and passerine birds have complex songs, whereas the large vocal repertoires of parrots comprise various call types associated with different behavioral contexts. Generally, bird song has two major functions: territorial defense and mate attraction. In the latter context, particularly in songbirds (Oscines), the evolution of male song repertoires has strongly been driven by sexual selection: Song complexity and repertoire size have been shown to be indicators of male quality and are thus crucial traits for female choice. Today, the age of phylogenetics provides new methods for the study of the mode and tempo of organismic diversification and of trait evolution, e.g., of vocal learning. As a striking result, song learning seems to be associated with species richness across the avian tree of life. This provided recent evidence for the theory that song learning can act as a pacemaker of evolution. The spatial variation of song dialects is often correlated with genetic diversification. Extreme cases are small isolated populations, for example, on islands. In the field, the effect of song diversification as a barrier for gene flow can best be observed in zones of secondary contact between close relatives. Even in cases of hybridization, differences of song might affect female choice and thus lead to assortative mating and prevent gene flow in one or even in both directions. These are probably the most exciting case studies, where speciation in action (or in reverse) can be studied in the wild.

Call variation of Crested Francolin (Dendroperdix sephaena) across Africa defies the effects of spatial gradients

“…The most plausible explanation for the vocal patterns observed in D. sephaena is that subspecies acquired distinctive vocalizations because of isolation in and adaptation to different habitats. Hetero-subspecific call variants possibly acted as prezygotic barriers, a explanation that is strongly supported by the responses to our playback experiments (Catchpole & Slater 2008, Päckert 2018). However, only molecular investigations can clarify whether this extends to speciation.…”

Asymmetric allelic introgression across a hybrid zone of the coal tit (Periparus ater) in the central Himalayas*

“…In songbirds (Oscines), territorial song plays a key role not only in territorial defense (intrasexual behavior) but also in mate choice (intersexual behavior; Naguib & Riebel, 2014; Päckert, 2018). Therefore, differences between song types facilitate assortative mating in secondary contact as shown for several oscine contact zones ( Ficedula flycatchers in central Europe: Qvarnström et al, 2010; Phylloscopus leaf warblers in the Pyrenees: Helbig et al, 2001).…”

“…In songbirds (Oscines), territorial song plays a key role not only in territorial defense (intrasexual behavior) but also in mate choice (intersexual behavior; Naguib & Riebel, 2014;Päckert, 2018) Manthey et al, 2012;Taylor et al, 2014).…”

Morphotypes or distinct species? A multilocus assessment of two East Asian scimitar babblers (Aves, Timaliidae)

“…This incident may suggest that vocalizations of the other species were not recognized as coming from a competitor by these individuals, which may indicate acoustic isolation between the two species, although a larger sample would be needed. It is widely accepted that vocal characters are good indicators of avian species limits (Päckert, Martens, Kosuch, Nazarenko, & Veith, ) because acoustic signals often play a significant role in species recognition and male choice (Päckert, ; Slabbekoorn, ), leading to a substantial increase in use of vocal traits in recent cases of avian species delimitation (Alström & Ranft, ; Alström et al, ; Feo, Musser, Berv, & Clark, ). However, we highlighted that further vocal tests were needed to confirm the divergence in vocal aspect.…”