TESTOSTERONE INDUCES SEXUAL RELEASE QUALITY IN THE SONG OF FEMALE CANARIES

We tested the sexual responsiveness of female canaries, Serinus canari a, to two sets of different types of female conspecific songs versus a n adult male conspecific song. Female songs were either spontaneously emitted ('S-songs') or were testosterone-induced ('T-songs'). Copulati on-solicitation displays (CSD) were used as an index of female sexual response. Playbacks were performed several days before and during egg laying, a period of natural sexual responsiveness of the females to so ng. We demonstrated that the weaker sexual displays of female canaries were recorded to S-songs, thus suggesting that these types of female songs do not contain fully functional sexual releasers. Three T-songs elicited high levels of sexual displays, thus demonstrating that testo sterone treatment map induce sexual release quality in the female song s. Study of the phonology of these three T-songs strongly suggested th at special song phrases map be good candidates as powerful sexual rele asers. To test the sexual value of these female song phrases, we carri ed out a third experiment, using hybrid songs where each of these spec ial T-song phrase types was included in a well-known heterospecific co ntext. Two phrases elicited high levels of sexual responses in females . Essential features of the male full song, such as broadband rapid fr equency modulations and high repetition rate, are retrieved in both fe male song phrases. Taken together, these data demonstrate that testost erone treatment not only induces a male-like structure in the songs of females, but also induces functionally 'male-like' songs. This result allows features of the vocal control network of testosterone-treated females to be compared with those of adult males singing full songs, t o distinguish neural correlates of testosterone-dependent full songs. However, because testosterone does not induce functionally male-like s ongs in all the females, neuroanatomical structure-function correlatio ns need detailed behavioural analysis.