Contextual flexibility in the vocal repertoire of an Amazon parrot
Por:
Christian Montes-Medina, Adolfo, Salinas-Melgoza, Alejandro, Renton, Katherine
Publicada:
26 ago 2016
Resumen:
Background: Understanding the role of avian vocal communication in
social organisation requires knowledge of the vocal repertoire used to
convey information. Parrots use acoustic signals in a variety of social
contexts, but no studies have evaluated cross-functional use of acoustic
signals by parrots, or whether these conform to signal design rules for
different behavioural contexts. We statistically characterised the vocal
repertoire of 61 free-living Lilac-crowned Amazons (Amazona finschi) in
nine behavioural contexts (nesting, threat, alarm, foraging, perched,
take-off, flight, landing, and food soliciting). We aimed to determine
whether parrots demonstrated contextual flexibility in their vocal
repertoire, and whether these acoustic signals follow design rules that
could maximise communication.
Results: The Lilac-crowned Amazon had a diverse vocal repertoire of 101
note-types emitted at least twice, 58 of which were emitted >= 5 times.
Threat and nesting contexts had the greatest variety and proportion of
exclusive note-types, although the most common note-types were emitted
in all behavioural contexts but with differing proportional
contribution. Behavioural context significantly explained variation in
acoustic features, where threat and nesting contexts had the highest
mean frequencies and broad bandwidths, and alarm signals had a high
emission rate of 3.6 notes/s. Three Principal Components explained 72.03
% of the variation in temporal and spectral characteristics of notes.
Permutated Discriminant Function Analysis using these Principal
Components demonstrated that 28 note-types (emitted by > 1 individual)
could be correctly classified and significantly discriminated from a
random model.
Conclusions: Acoustic features of Lilac-crowned Amazon vocalisations in
specific behavioural contexts conformed to signal design rules.
Lilac-crowned Amazons modified the emission rate and proportional
contribution of note-types used in each context, suggesting the use of
graded and combinatorial variation to encode information. We propose
that evaluation of vocal repertoires based on note-types would reflect
the true extent of a species' vocal flexibility, and the potential for
combinatorial structures in parrot acoustic signals.
Filiaciones:
Christian Montes-Medina, Adolfo:
Univ Nacl Autonoma Mexico, Inst Biol, Posgrad Ciencias Biol, Mexico City, DF, Mexico
Salinas-Melgoza, Alejandro:
Univ Michoacana, Fac Biol, Morelia, Michoacan, Mexico
Renton, Katherine:
Univ Nacl Autonoma Mexico, Inst Biol, Estn Biol Chamela, Apartado Postal 21, Chamela 48980, Jalisco, Mexico
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