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Sarah Kiefer, Doctoral Student

Song acquisition in nightingales is not limited to an early sensitive period in juvenile birds. Rather, lab tutored males can add new song-types to their repertoire as adults and are thus ‘open ended’ learners (1). For my Diploma thesis, I tested whether an open-ended learning strategy can also be detected under natural field conditions. For this I analyzed differences in the size of song type repertoires of territorial nightingales of different ages. Males in their first breeding season were indeed found to have substantially smaller repertoires than older males whose repertoire size was significantly larger than that of yearlings. Given that older nightingales do not generally increase their repertoire size between successive breeding seasons (2), these results demonstrate a significant leap in repertoire size from the first to the second breeding season. My current project aims to elucidate the causal and functional mechanisms of such age related song characteristics. In learning experiments I will examine whether differences in repertoire size arise from constraints in learning capacity or selective learning in juveniles. In structural analyses I will examine whether parameters that reflect the acoustic complexity of songs are key variables for differences in repertoire size.

 

(1) Todt, D. & Geberzahn, N. (2003) Age-dependent effects of song exposure: song crystallisation sets a boundary between fast and delayed vocal imitation. Animal Behaviour 65, 971-979. (2) Kipper, S., Mundry, R., Hultsch, H. & Todt, D. (2004) Long-term persistence of song performance rules in nightingales (Luscinia megarhynchos): A longitudinal field study on repertoire size and composition. Behaviour 141, 371-390.