Testing the flexibility of song type bout duration in the chaffinch (Fringilla coelebs).

Many songbird species with small song type repertoires repeat each type a few times before 'switching to the next. Thus, their singing style may constrain their ability to switch. However, the proximate causation of song type switching is poorly understood. We exposed male chaffinches to (nonoverlapping) playbacks of single renditions of their own songs rather than a series of songs, thus stimulating them with a single external auditory event. The most prominent effect of the playback was an increase in the duration of the current song type bout. If the song type played back was different to that the subject was singing at the time, bout duration increased less than if it was of the same song type. The short-term changes induced by the playback suggest that the auditory input increases the motivational level for a particular song type. In the chaffinch this results in a delayed switch rather than in song type matching as a reaction to acoustic stimulation by conspecific song. (C) 2000 The Association for the Study of Animal Behaviour.