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Is the Soft Song of the Brownish-Flanked Bush Warbler an Aggressive Signal?

Authors

  • Canwei Xia,

    1. Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
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  • Jiayu Liu,

    1. Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
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  • Per Alström,

    1. Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden
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  • Qiao Wu,

    1. Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
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  • Yanyun Zhang

    Corresponding author
    • Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China
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Correspondence

Yanyun Zhang, Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, China.

E-mail: zhangyy@bnu.edu.cn

Abstract

Soft songs have been detected in many songbirds, but in most species, research on soft songs has lagged behind studies of broadcast songs. In this study, we describe the acoustic features of a soft song in the brownish-flanked bush warbler Cettia fortipes. Compared with the broadcast song, the warbler's soft song was characterized by a lower minimum frequency and longer duration, and it had a higher proportion of rapid frequency modulation notes. Using playback experiments, some in combination with mounted specimens, we found different responses to soft and broadcast songs, and we found that soft song can predict aggressive escalation (attack). We conclude that the soft song is an aggressive signal in this species.

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