Female Prothonotary Warblers Protonotaria citrea sing during the mate acquisition period

Female song in passerine birds may be more common than traditionally assumed, but it is not well‐documented or understood, especially in migratory species. We describe the first evidence of sex‐specific songs produced by female Prothonotary Warblers, as well as the results of playback trials aimed at exploring the adaptive function (if any) of this female‐specific vocalization. Based on the behaviour of three females and our playback trials, we suggest that these unique songs are related to mate acquisition during the early stages of courtship.