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

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.