Comparação e descrição de parâmetros acústicos do canto de Volatinia jacarina (Aves: Emberizidae) no contexto de seleção sexual

AUTOR(ES)

Alexandre Ferreira de Souza Dias

DATA DE PUBLICAÇÃO

2009

RESUMO

Bird songs may convey information about the quality of the male, and females can access this information during partner choice. The aim of this study was to test for correlations between acoustic parameters of songs from Volatinia jacarina males and their physical attributes. First we determined, through quantitative analysis, the degree of stereotypy in the songs of a population at central Brazil during two consecutive reproductive seasons. Spectrogram cross correlation analyses indicated that the average intra-individual similarity score (0.70 0.08) is almost three times higher than the average inter-individual similarity score (0.24 0.05), one of the highest stereotypy scores reported so far for birds. The data suggest that microdialects exist on this species, consistent between very small geographic scales. It was also observed that its song suffers small changes throughout the reproductive season, indicating the existence of plasticity on adult songs. In second place, a vocal performance index was generated using the triangular distribution of song duration vs. frequency bandwidth, based upon how close each male was to the upper-bound limit of this distribution. Stepwise regression analyses revealed a negative relationship between vocal performance and a molt index, i.e. how early in the season individuals molt into nuptial plumage. Vocal performance was also found to relate positively with song output, and with food abundance (density of grass seeds) within males territories. These data suggest that blue-black grassquit songs contain reliable information regarding male quality.

ASSUNTO(S)

seleção sexual correlação cruzada de espectrogramas bird song upper bound limit bioacoustics vocal performance index spectrogram cross correlation vocal stereotypy bioacústica índice de desempenho de canto sexual selection canto de aves limite superior de desempenho ciencias biologicas estereotipia vocal

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