Female song and elaborate female coloration: Comparing signaling traits in tropical versus temperate songbirds

Geographic and gender biases in the history of ornithology have led to missed opportunities, and in some cases, backwards understanding of key evolutionary and behavioral processes. In studies of elaborate coloration and song, female birds have historically been neglected. The main framework for thinking about the evolution of elaborate traits has been sexual selection, whereby competition for mates has led to elaborate coloration and long, complex songs in males. Females have often been ignored or assumed not to change. Here we review current understanding of how these elaborate traits have evolved in temperate versus tropical areas. Ongoing research on orioles, other blackbirds, and all songbirds indicates that female song is much more common than previously thought. Social selection acting on both females and males throughout the year likely played an important role in the original evolution of bird song in both sexes. In many cases, the evolution of sexual dimorphism in both coloration and song is driven by the loss of elaboration in females, rather than the gain of elaboration in males. Accounting for both male and female display traits will lead to a clearer understanding of the evolution of coloration and song, which will also facilitate a more comprehensive understanding of the full scope of topics in avian ecology, evolution, behavior, and conservation.