Does intruder distance affect singing responses in nightingales?

Conny Bartsch, Doctoral Student

Male songbirds often establish and maintain territories throughout the breeding season and one of the main functions of song is thought to serve this function (review in Catchpole & Slater 2008). Hereby, males apply different singing strategies to communicate with each other. One strategy is related to the temporal placement of songs where two males either alternate in singing their songs or they tend to overlap their songs which has been shown to be a more aggressive behaviour. Another way to address a conspecific is song type matching: one bird repeats the song type formerly sang by its opponent (review in Todt & Naguib 2000). The distance of a singing rival plays a crucial role within these dyadic singing interactions, expected to be perceived as more threatening the closer the rival is. This distance therefore may have a strong influence on the behaviour of the resident, e.g. in the number of matched songs. To test this hypothesis I conduct playback experiments on a population of nightingales in the Treptower Park, Berlin. I simulate intruders singing in different distances to the resident by using interactive playbacks during nocturnal song. Follow-up playbacks performed in the following morning will allow me to also get access to long-term effects of nocturnal playbacks such as approaches to the loudspeaker and will show whether differences in intruder distance at night leads to changes in response patterns the following morning.  Such long-term effects of nocturnal playbacks have recently been shown in a study by Schmidt et al (2007).

 

Literature cited:

Catchpole, C. K. & Slater, P. J. B. (2008). Bird song. Biological themes and variation. 2nd edition, Cambridge University Press, Cambridge. Todt, D. & Naguib, M. (2000). Vocal interactions in birds: The use of song as a model in communication. Advances in the Study of Behaviour, 29, 247-296. Schmidt, R., Amrhein, V., Kunc, H. P. & Naguib, M. (2007). The day after: effects of vocal interactions on territory defence in nightingales. Journal of Animal Ecology, 76, 168-173.