Female song is structurally different from male song in Orchard Orioles, a temperate-breeding songbird with delayed plumage maturation

. Female birds in many temperate species are thought to sing reduced or quieter songs and appear to sing less often than their male counterparts. Therefore, female song may be easily overlooked. Increasingly, researchers are recording female song in well-studied species previously assumed to have little or no female song. In this study, we document the extensive use of female song in Orchard Orioles ( Icterus spurius ), a species with delayed plumage maturation where female song had not been well-documented. Based on observations of females singing in the early breeding season, we hypothesized that female song may function for mate attraction. To formally investigate whether females sing specifically early in the season, we assessed singing rates of each sex throughout the breeding season. We also performed detailed acoustic analyses comparing male and female song structure. Females sang significantly less often than males, and female and male songs were statistically different for five of eight variables investigated, indicating that the two en cinco de las ocho variables investigadas, indicando que los dos sexos cantan cantos acústicamente diferentes. Sin embargo, las hembras también cantaron más frecuentemente que lo asumido inicialmente, sugiriendo que los investigadores pueden estar pasando por alto el canto de las hembras de otras especies si no lo están buscando directamente, en particular en especies en donde los machos de primer año y las hembras tienen coloraciones similares. Por lo tanto, este estudio resaltamos la necesidad de re-explorar sistemas bien estudiados. Se requiere más investigación para determinar si el canto de las hembras tiene una función y como es esta función.