Vocal repertoires of male and female non-human primates can differ by presence or absence of vocalizations, acoustic structure, and usage. These differences are sometimes evident in those species exhibiting specialized singing behaviours, like gibbons. In this study, we studied the song structure of 11 groups of indris inhabiting the Parc National Andasibe/Mantadia and the neighbourhoods. Chorus were sampled between September 2004 and October 2007. A total of 19 singing males and 11 singing females were recorded during diurnal surveys and data on their singing activity were collected and saved along the sound files. We aimed to quantify the amount of singing by the respective sexes, and to illustrate sex-specific acoustic patterns characterizing the calls. The song structure analysis showed that 1 note type is emitted only by males and 2 types only by females. Independent of the typology, males emit fewer notes (19.44 ± 6.52) than females (32.51 ± 10.53), but male notes are generally longer (P < 0,001) and cover a narrower fundamental frequency (F0) range (P < 0,001). Taking into account that the song of indri exhibited distinguishable note types, statistic within-type analyses showed that vocal emissions given during the song by males always showed longer duration (P < 0,02) and significantly different F0 at the note beginning (P < 0,05) than those emitted by females. Differences may be due to sex specific morphological features and, given the existence of differences in sex composition among groups, can play a role in determining group-specific structure of the song.
SEX DIFFERENCES IN THE SONG OF INDRI INDRI
GIACOMA, Cristina;GAMBA, Marco;
2008-01-01
Abstract
Vocal repertoires of male and female non-human primates can differ by presence or absence of vocalizations, acoustic structure, and usage. These differences are sometimes evident in those species exhibiting specialized singing behaviours, like gibbons. In this study, we studied the song structure of 11 groups of indris inhabiting the Parc National Andasibe/Mantadia and the neighbourhoods. Chorus were sampled between September 2004 and October 2007. A total of 19 singing males and 11 singing females were recorded during diurnal surveys and data on their singing activity were collected and saved along the sound files. We aimed to quantify the amount of singing by the respective sexes, and to illustrate sex-specific acoustic patterns characterizing the calls. The song structure analysis showed that 1 note type is emitted only by males and 2 types only by females. Independent of the typology, males emit fewer notes (19.44 ± 6.52) than females (32.51 ± 10.53), but male notes are generally longer (P < 0,001) and cover a narrower fundamental frequency (F0) range (P < 0,001). Taking into account that the song of indri exhibited distinguishable note types, statistic within-type analyses showed that vocal emissions given during the song by males always showed longer duration (P < 0,02) and significantly different F0 at the note beginning (P < 0,05) than those emitted by females. Differences may be due to sex specific morphological features and, given the existence of differences in sex composition among groups, can play a role in determining group-specific structure of the song.
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