Female song in tinkerbirds (family Lybiidae)

Abstract

In species that are sexually monomorphic, it can be challenging to ascertain whether both males and females sing. This is particularly the case when there are no discernible differences in the vocalisations of each sex. It is known that females of many African barbet species (family Lybiidae), sing as part of duets with their male partners. Nevertheless, in sexually monomorphic tinkerbirds that do not engage in duets, there is a paucity of knowledge regarding the extent of female song. A combination of colour-ringed individuals and molecular sexing was employed to determine the sex of the birds recorded singing along a transect across a hybrid zone between Yellow-fronted Pogoniulus chrysoconus and Southern Red-fronted P. pusillus Tinkerbirds in South Africa and Eswatini. Of the 166 sexed birds for which sex was determined and whose songs were recorded, 20 were female. Only three females were found singing on more than one occasion and just one in multiple years. The function of female song in tinkerbirds remains to be elucidated. As in this study birds sung in response to playback, female song could play a role in territorial defence. At the same time, as female song is present in several genera of African barbets, it might be an ancestral trait in the family.