Documentation of female song in a newly recognized species, the Puerto Rican Oriole (Icterus portoricensis)

Abstract

Evolutionary biologists often assume that male competition for females is the root of the evolution of elaborate coloration and song. However, recent findings show that in the ancestral history of songbirds, it is likely that song occurred in both males and females. Surprisingly, no data exist on female song for many species of birds. We investigated whether the Puerto Rican Oriole (Icterus portoricensis), a tropical songbird, exhibits both male and female song. For this project we marked individuals with sex-specific color bands and confirmed sex using genetic sexing. We repeatedly recorded both male and female orioles singing. Furthermore, female Puerto Rican Oriole song appears to be similar to male song, with no obvious differences in structure. Our study provides further evidence of the ubiquity of female song in tropical songbirds. Finally, our findings provide support that female song is ancestral in the Caribbean oriole clade, and that song dimorphism in temperate breeding species is a result of a loss of female song.