New metric to assess vocal performance in complex birdsong

[Nicole Geberzahn <>]

Dear colleagues,

We would like to draw your attention to the following paper:

Geberzahn and Aubin (2014) Assessing vocal performance in complex birdsong: a novel approach. BMC Biology 2014, 12:58

The paper is open access and can be downloaded here: http://www.biomedcentral.com/content/pdf/s12915-014-0058-4.pdf

Abstract
Background: Vocal performance refers to the ability to produce vocal signals close to physical limits. Such motor skills can be used by conspecifics to assess a signaler’s competitive potential. For example it is difficult for birds to produce repeated syllables both rapidly and with a broad frequency bandwidth. Deviation from an upper-bound regression of frequency bandwidth on trill rate has been widely used to assess vocal performance. This approach is, however, only applicable to simple trilled songs, and even then may be affected by differences in syllable complexity.
Results: Using skylarks (Alauda arvensis) as a birdsong model with a very complex song structure, we detected another performance trade-off: minimum gap duration between syllables was longer when the frequency ratio between the end of one syllable and the start of the next syllable (inter-syllable frequency shift) was large. This allowed us to apply a novel measure of vocal performance - vocal gap deviation: the deviation from a lower-bound regression of gap duration on inter-syllable frequency shift. We show that skylarks increase vocal performance in an aggressive context suggesting that this trait might serve as a signal for competitive potential.
Conclusions: We suggest using vocal gap deviation in future studies to assess vocal performance in songbird species with complex structure.

Best wishes,

Nicole Geberzahn

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Nicole Geberzahn
Université Paris Ouest Nanterre La Défense
Laboratoire Éthologie Cognition Développement
Bâtiment BSL - 200 avenue de la République
92001 Nanterre Cedex
France

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