Absence of song suggests heterogeneity of vocal-production learning in hummingbirds

Abstract

Hummingbirds have been recognized, along with songbirds and parrots, as capable of learning songs. However, it is still unclear whether singing can be treated as a homologous trait within the family, analogous to songbirds. Therefore, we systematically compared the information about hummingbird vocalizations in the literature in a phylogenetic framework. In general, songs were emitted by perching males in a reproductive context, while calls were mainly in agonistic contexts. Singing was ancestral in most of the nine major hummingbird clades, but has been lost at least once in the mountain gem clade and twice in the bee clade. This evolutionary loss of singing might suggest heterogeneity of vocal-production learning.

Differences in vocal brain areas and astrocytes between the house wren and the rufous-tailed hummingbird

“…Both species exhibited brain nucleus associated with vocal production and learning, along with GFAP astrocytes, indicating a convergent neural substrate for learning ( Jarvis et al, 2000 ; Araya and Wright, 2013 ; Johnson and Clark, 2020 ; Kuhl et al, 2021 ). Recent findings demonstrate that hummingbirds have acquired songs functionally equivalent to those of songbirds, suggesting homology in vocal brain areas ( Monte et al, 2023 ). This study uniquely establishes a relation between the convergence of GFAP astrocytes and regions involved in motor control ( Morquette et al, 2015 ; Xin et al, 2019 ; Corkrum et al, 2020 ; Turk and SheikhBahaei, 2022 ).…”

“…Despite the distant phylogenetic relationship between hummingbirds and songbirds, there is evidence of convergent learned singing in these species ( Gahr, 2000 ; Jarvis et al, 2000 ; Araya and Wright, 2013 ; Johnson and Clark, 2020 ; Kuhl et al, 2021 ). The functionality of hummingbird singing is equivalent to that of songbirds, and this character is generally considered ancestral and widespread but only sporadically present ( Monte et al, 2023 ). Notably, many tropical hummingbirds coexisting with songbirds have remarkable songs ( Araya and Wright, 2013 ) that vary in complexity.…”