SEX-ROLE REVERSAL IN SONG? FEMALES SING MORE FREQUENTLY THAN MALES IN THE STREAK-BACKED ORIOLE

Birds in which both sexes produce complex song are more common in the tropics than in the temperate north, where typically only males sing. Yet surprisingly little is known about female song characteristics in most tropical species. Here we present a comparison of female and male singing behaviors in the Streak-backed Oriole (Icterus pustulatus), a tropical songbird in which both sexes perform solo songs. Females sing much more frequently than males and produce songs with similar acoustic complexity. Rates of singing by both sexes were higher during breeding than postbreeding while the rates of most other vocal- izations did not change, suggesting that song plays an important role in breeding. To our knowledge, this is the first reported spe - cies in which females regularly sing at higher rates than males; however, few studies have examined female song in other sexu- ally monomorphic or weakly dimorphic species, so such patterns might not be unique.