01753nas a2200181   4500008004600000245008100046210006900127520118800196653001701384653001001401653001801411653000901429100002201438700002201460700002001482700002101502856004801523       Submitted                   eng d     00aFemales alter their song when challenged in a sex-role reversed bird species0 aFemales alter their song when challenged in a sexrole reversed b3 aAbstract&nbsp;&nbsp;Birdsong serves to attract mates and to deter territorial rivals. Even though song is not restricted to males, this dual function has almost exclusively been demonstrated for male song. To test the generality of hypotheses on birdsong, we investigated female song in the sex-role reversed, classically polyandrous African black coucal (Centropus grillii) in the context of female–female competition. We compared spontaneously vocalizing females with females vocally responding to a playback simulating a conspecific intruder. Females changed vocal parameters in response to playbacks: They lowered the pitch of their vocalizations and enhanced the duration of song elements when being challenged. Also, the composition of the vocalizations was altered. There was no significant correlation between pitch and body size parameters in spontaneous song, but there was for response songs, with larger females having a lower pitch. These changes in vocal properties suggest that the vocalizations are important for mutual assessment of competitive abilities in females. Our findings confirm the general role of intrasexual competition in vocal communication of birds.10abioacoustics10abirds10acommunication10asong1 aGeberzahn, Nicole1 aGoymann, Wolfgang1 aMuck, Christina1 aCate, Carel, ten  uhttp://dx.doi.org/10.1007/s00265-009-0836-0