Since 1977 a new population of the scarlet rosefinch Carpodacus erythrinus was established in typical alpine bog habitat in southern Bavaria near Garmisch-Partenkirchen. Research on phenology, ecology and breeding biology was done by the Institute of Ornithology, Garmish-Partenkirchen. In addition, we studied the acoustic behaviour of this population. During the whole season of 1989 we controlled the complete population in three adjacent bogs. Nearly 30 males-most of them individually colour-ringed-were tape-recorded on several days and times of day in various behavioural contexts. Also playback experiments were made. We found 12 different types of the short and loud advertising song (Germ. 'Kurzstrophe'). The long and low-voiced song (Germ. 'Langstrophe') was used only in excitement. Each male, with one exception, used only one song-type. The song quality of red (adult) and green (juvenile) males was compared. Phenomena such as song-matching, changing of song-type during the breeding season and microgenesis were described.