RESPONSE OF GREAT TITS TO ESCALATING PATTERNS OF PLAYBACK

The short-term signaling and behavioral responses of male great tits (Parus major) to playback simulating a territorial intrusion were investigated. Playback was interactive and escalated from a treatment (T1) in which strophe length was not related to that sung by the subject (random increase/decrease of playback strophe length), to treatment (T2) with increasing relative strophe length and then to a third treatment (T3) which increased relative strophe length and in addition overlapped the subject's strophe. The recording of the singing pattern and an accurate description of the movements of the birds was achieved by the use of a passive, non-intrusive acoustic location system (ALS). The difference in response to these three treatments were most noticable in approach and overlapping by the subjects. Males overlapped playback during T1 and T2 but reduced overlapping considerably when they were overlapped in T3. There was also a tendency for males to change strophe length in the opposite direction to playback, i.e. increasing their strophe length when playback decreased strophe length and vice versa. This study supports the idea, that great tits can extract information from short-term changes in singing patterns about a willingness to escalate a conflict. The birds seem to be able to adjust their response depending on the perceived level of threat.