ROLES OF THE SONG REPERTOIRE IN RED-WINGED BLACKBIRDS

Male red-winged blackbirds, like many other discontinuous singers, possess a repertoire of song types or renditions. We observed the behavior of four territorial males for over 500 h and recorded more than 7,600 songs to determine the functions of these repertoires. Analysis of the recordings and behavior revealed the following: 1. Males in the present study have repertoires of 5-7 stereotyped song renditions. The frequency of delivery of each male's renditions differed during the first and second halves of the breeding season. 2. There was no obvious tendency for the males to use specific renditions in certain social or environmental contexts. 3. Of all rendition changes, 80% were immediately preceded by perch changes. Of the rendition changes occurring when the males were stationary, approximately 70% were in the presence of females or in apparent countersinging bouts with neighboring males, suggesting that both intersexual and intrasexual selection have influenced the elaboration of repertoires. 4. Males did not avoid low recurrence intervals. This contrasts with other species with small repertoires which do tend to avoid low recurrence intervals. © 1979 Springer-Verlag.