Geissmann, T., 1986: Mate change enhances duetting activity in the siamang gibbon (Hylobates syndactylus). Behaviour 96: 17-27.

Mate change enhances duetting activity in the siamang gibbon (Hylobates syndactylus)

T. Geissmann
Anthropological Institute, University Zürich-Irchel

Abstract: Siamang gibbons produce long and complex duet songs. The hypothesis that duetting may act as advertisement of the presence and the status of a mated pair has repeatedly been suggested for duetting birds. If a pair bonding effect of the duet is actually attained through a partner-directed learning effort resulting in a pair-specific duet, the learning investment should be concentrated into a time period as short as possible in order to avoid competitors. Therefore, after the formation of a new pair, an increase of singing activity should be expected. In order to test this prediction, the singing activity of a pair of captive siamangs before and after a partner exchange was compared. In the newly formed pair, an increase in singing activity was observed. Additional observations on a second new pair show a similar trend. In this case, both new mates remained in their familiar place so that their singing activity was unlikely to be affected by the process of establishing a new territory.

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