Vocal acoustics in the endangered proboscis monkey (Nasalis larvatus)

The endangered proboscis monkey (Nasalis larvatus) is a sexually highly dimorphic Old World primate endemic to the island of Borneo. Previous studies focused mainly on its ecology and behavior, but knowledge of its vocalizations is limited. The present study provides quantified information on vocal...

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Bibliographic Details
Published in:	American journal of primatology Vol. 76; no. 2; pp. 192 - 201
Main Authors:	Röper, K.M., Scheumann, M., Wiechert, A.B., Nathan, S., Goossens, B., Owren, M.J., Zimmermann, E.
Format:	Journal Article
Language:	English
Published:	United States Blackwell Publishing Ltd 01-02-2014 Wiley Subscription Services, Inc
Subjects:	Acoustics Animal ecology Animals Behavior, Animal Borneo Circadian Rhythm Colobinae - physiology Conservation of Natural Resources Endangered Species Female loud calls Male Nasalis larvatus non-invasive tool for conservation Old World monkeys Primate behaviour Primate biology proboscis monkeys Protected species River banks Sound Spectrography Speech Acoustics Verbal communication Vocalization, Animal vocalizations Wildlife Wildlife refuges Borneo vocalizations loud calls non-invasive tool for conservation proboscis monkeys acoustics
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Summary:	The endangered proboscis monkey (Nasalis larvatus) is a sexually highly dimorphic Old World primate endemic to the island of Borneo. Previous studies focused mainly on its ecology and behavior, but knowledge of its vocalizations is limited. The present study provides quantified information on vocal rate and on the vocal acoustics of the prominent calls of this species. We audio‐recorded vocal behavior of 10 groups over two 4‐month periods at the Lower Kinabatangan Wildlife Sanctuary in Sabah, Borneo. We observed monkeys and recorded calls in evening and morning sessions at sleeping trees along riverbanks. We found no differences in the vocal rate between evening and morning observation sessions. Based on multiparametric analysis, we identified acoustic features of the four common call‐types “shrieks,” “honks,” “roars,” and “brays.” “Chorus” events were also noted in which multiple callers produced a mix of vocalizations. The four call‐types were distinguishable based on a combination of fundamental frequency variation, call duration, and degree of voicing. Three of the call‐types can be considered as “loud calls” and are therefore deemed promising candidates for non‐invasive, vocalization‐based monitoring of proboscis monkeys for conservation purposes. Am. J. Primatol. 76:192–201, 2014. © 2013 Wiley Periodicals, Inc.
Bibliography:	istex:2E47E29CA5F9BCFDB02CDB9C5E8A320D7BD83B94 ArticleID:AJP22221 Konrad-Adenauer-Stiftung ark:/67375/WNG-RVBVCC1S-C DAAD ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1
ISSN:	0275-2565 1098-2345
DOI:	10.1002/ajp.22221