CHANGES IN THE BEHAVIOURAL AND SINGING PATTERN OF Indri indri IN PLAYBACK EXPERIMENTS

Indri indri is a territorial lemur, endemic of the eastern Madagascar rainforest. It produces impressive howling cries within a complex sequence of utterances, usually called “the song of the indri”. This behavior attracts many tourists and local guides are likely to playback the song in order to please the tourists. The question is whether the “playbacks to please tourists” can be a disturbance for the indris. For the purpose of this study we recorded for the first time indri’s behavioral response to playback of songs in the Maromizaha rainforest. Three family groups were tested by playback of three song’s categories: a) emitted by the group itself, b) emitted by neighboring groups, and c) emitted by distant unknown groups. Our objective was to verify to what extent behavioral and vocal responses to playback stimuli might differ from the spontaneously occurring songs. Indris reacted to playbacks with alarm signals and patrolling the territory. They also reduced feeding and resting activities. Acoustically speaking, when compared to spontaneous songs, playback responses showed a decrease in the duration of the initial part of the song, in terms of number and duration of the notes. Moreover, notes of the descending phrases were emitted with lower fundamental frequency. Our results suggest that the adoption of specific guidelines for the use of playbacks during touristic activities must be considered.