Format

Send to

Choose Destination
Am J Primatol. 2014 Feb;76(2):192-201. doi: 10.1002/ajp.22221. Epub 2013 Oct 1.

Vocal acoustics in the endangered proboscis monkey (Nasalis larvatus).

Author information

1
Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany.

Abstract

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.

KEYWORDS:

acoustics; loud calls; non-invasive tool for conservation; proboscis monkeys; vocalizations

PMID:
24123122
DOI:
10.1002/ajp.22221
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center