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Singing in a wolf chorus: structure and complexity of a multicomponent acoustic behaviour


Abstract


Wolf choruses (Canis lupus) are complex, multicomponent signals, composed by a series of different vocalizations emitted by a pack. Although howls, the main component, have been highly studied, poor attention has been drawn upon the other vocalizations of the chorus.

In this study, we investigate the structure of the chorus by means of the analysis and the quantification of the different components, taking advantage both of the digital sound recording and analysis, and of the modern statistical methodologies. We provide for the first time a detailed, objective description of the types of call emitted during the wolf howlings, combining spectrographic examinations, spectral analyses and automated classifications, with the aim to identify different types of call.

Our results show that wolf choruses have a rich, complex structure, that reveals six other types of call, to be added to those howls already described in literature.

Wolf choruses are typically composed by other three different types of calls: the bark, i.e. relatively long calls characterized by low frequencies and the presence of harsh components (deterministic chaos); the whimper, characterized by a harmonic structure and a very short duration; and the growl, a call with a noisy structure, low frequencies but relative long duration.

 Although further investigations are necessary to understand the meaning of the different calls, this research provides a basis for those studies that aim to compare wolves and other canids vocal behaviour.

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Keywords


wolf; vocalizations; canis lupus; chorus howling; wolf howling; acoustic repertoire; fundamental frequency; automatic classification; silhouette; cluster analysis

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DOI: http://dx.doi.org/10.4404/hystrix-28.2-12019

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Copyright (c) 2017 Daniela Passilongo, Marianna Marchetto, Marco Apollonio

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Hystrix, the Italian Journal of Mammalogy ISSN 1825-5272 (electronic version) 0394-1914 (printed version) Impact Factor (2016) 1.479, CiteScore (2016) 3.51.
Published by Associazione Teriologica Italiana
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Creative Commons LicenseWorks published in Hystrix are licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.