SINGING INTERACTIONS IN COAL TITS, PARUS-ATER - AN EXPERIMENTAL APPROACH

Two playback experiments were carried out to test the prediction on coal tits that singing rate could be used to assess the vigour of rival males, and that song length might be used in the same way, during singing interactions. Playbacks of songs with increasing rate inhibited the songs of responding birds, but induced more calls in response. The results suggested that a bout of singing with increasing rate is reacted to as a more serious threat than one with decreasing song output. The playback of long songs induced a greater number of calls in response, while fewer were produced during playback of shorter songs. The results suggest that a bout oflong songs is responded to as a more serious threat than one of short songs. © 1994 Academic Press, Inc. All rights reserved.