Singing of Claudia's Leaf-warbler [Phylloscopus claudiae) in aggressive contexts: role of song rate, song type diversity and song type transitional pattern

摘要

In many songbirds, maies vary certain aspects of their singing behavior when engagea in territorial interactions. Song rate, song type switching rate, song matching, song overlapping, and the usage of specific song types were proposed to be aggressivesignais. It is well known that transitions between différent song types in a song séquence are non-random in many species, but the signaling significance of non-random vocal streams is poorly understood. We asked whether singing plays a role in male-male interactions in Claudia's Leaf-warbler. Along with more traditional metrics (i.e., song length, song rate, song type switching rate and song type diversity), we used (1) song séquence linearity (5LIN) and consistency (SC0NS) indexes, and (2) appliedan information theory approach by means of a first-order relative entropy (REj) calculation to analyze the role of song type transitional patterns in male-male interactions. The study was conducted in April-June 2016 in Hupingshan National Nature Reserve, Hunan province, China. We simulated territorial intrusion by broadcasting Claudia's Leaf-warbler songs in territories. Experiments involved 14 différent maies. A comparison of spontaneous singing with that elicited by playback showed that song rate and song type diversity increased, and that entropy decreased. By contrast, SUN and SC0NS, though significantly correlated with REl5 did not differ between spontaneous singing and singing in response to playback. The decrease of entropy means that the transitions between différent song types in a song séquence were determined more by specific factors and predictable and thus more non-random. However, thèse results were weak, as the decrease of RE, did not coincide with the expected increase of S_(LIN), S_(CONS) and S. Our results are thus partly consistent with the idea that non-random vocal structures, along with other song parameters, could play a role in male-male compétition.