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Circadian long call distribution in wild orangutans


Ross, M D; Geissmann, T (2009). Circadian long call distribution in wild orangutans. Revue de Primatologie, 1:online.

Abstract

We present first data on circadian long call distribution of wild orangutans in Northwest Borneo. Data were collected during two months in Batang Ai National Park. A total of
151 male long calls were heard, exhibiting a bimodal distribution pattern with peaks at 05:00-06:00 hours and 18:00-19:00 hours. An earlier study found pronounced differences between the calling rates of Bornean orangutans, which showed an almost unimodal call
distribution with its peak at mid-morning, and those of Sumatran orangutans, which showed a bimodal call distribution with a distinct calling peak at predawn and a more moderate peak near dusk (MacKinnon 1974). Our findings from Batang Ai resemble more closely the pattern reported for Sumatra than those reported for other Bornean
localities and, therefore, contradict earlier reports suggesting a Sumatra-Borneo dichotomy in orangutan call distribution. In addition, orangutans in Batang Ai were heard to regularly emit long calls throughout the night. This behaviour is unusual for a diurnal species.

We present first data on circadian long call distribution of wild orangutans in Northwest Borneo. Data were collected during two months in Batang Ai National Park. A total of
151 male long calls were heard, exhibiting a bimodal distribution pattern with peaks at 05:00-06:00 hours and 18:00-19:00 hours. An earlier study found pronounced differences between the calling rates of Bornean orangutans, which showed an almost unimodal call
distribution with its peak at mid-morning, and those of Sumatran orangutans, which showed a bimodal call distribution with a distinct calling peak at predawn and a more moderate peak near dusk (MacKinnon 1974). Our findings from Batang Ai resemble more closely the pattern reported for Sumatra than those reported for other Bornean
localities and, therefore, contradict earlier reports suggesting a Sumatra-Borneo dichotomy in orangutan call distribution. In addition, orangutans in Batang Ai were heard to regularly emit long calls throughout the night. This behaviour is unusual for a diurnal species.

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Additional indexing

Other titles:Distribution circadienne des cris longs (long calls) chez l’orang-outan en milieu naturel
Item Type:Journal Article, not refereed, original work
Communities & Collections:07 Faculty of Science > Department of Anthropology
Dewey Decimal Classification:300 Social sciences, sociology & anthropology
Language:English
Date:2009
Deposited On:18 Feb 2010 15:52
Last Modified:05 Apr 2016 13:49
Publisher:Société Francophone de Primatologie
ISSN:2077-3757
Official URL:http://primatologie.revues.org/219
Permanent URL: http://doi.org/10.5167/uzh-28723

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