AUDITORY EXPERIENCE AND SONG DEVELOPMENT IN THE CHAFFINCH FRINGILLA COELEBS

The present paper describes the results of experiments designed to evaluate the importance of auditory-motor experience in the development of song in the Chaffinch. For this purpose a number of Chaffinches collected as nestlings or adults were deafened by extirpating the cochlea at different ages. Recordings of their song made subsequently provide the material on which the paper is based. Since the results of the experiments can only be interpreted in the light of knowledge of normal song development, the latter is described from the observation of previous workers and from some new material. Of the 20 males deafened, only three came into full song of their own accord; song was induced in the rest by the administration of testosterone phenylacetate or testosterone propionate. Songs of abnormal length were common among first-year males though males deafened when two or more years old produced song of the normal length. The song of male Chaffinches deafened as adults, that is after they had produced full song for one or more breeding seasons, was infistinguishable from that produced by intact adult males. They even went through a “plastic” song stage in which some “intermediate” themes occurred. A first-year male deafened when it had almost stabilized its song produced song that gradually deviated more and more from normal song. This indicates that the bird had not yet laid down a long-term memory of its song independent of auditory feedback. First-year male Chaffinches deafened during early spring, mid-winter and late sumer, respectively, show that the more they were deprived of the normal period of auditory-motor experience, the simpler was the song they produced in their first spring. Thus, at the time of deafening they had acquired a particular auditory-motor experience, and it is the type of element established up to that time that is incorporated into full song. Male chaffinches brought into the laboratory as nestlings and deafened when three months old produced a virtually sfyctureless song, in which the only recognizable element was a sound reminiscent of the juvenile “chirrup”. The subsong and other calls of these birds were also highly abnormal. Song development in the Chaffinch clearly starts before song as such has made its appearance. The available evidence suggests that the kind of song a male Chaffinch produces depends directly on its auditory-motor experience before deafening. There is no indication that deafening achieves its effects on the resultant song by interfering with the hormonal substrate. Relatively stable song end patterns develop in the absence of auditory feedback, so their occurrence does not necessitate the postulation of templates or preconceived patterns. Song development differs markedly from species to species.