Individuality and stability in male songs of cao vit gibbons (Nomascus nasutus) with potential to monitor population dynamics.

Jun-Juan Feng,Liang-Wei Cui,Chang-Yong Ma,Peng-Fei Fan,Han-Lan Fei,Johan J Bolhuis

doi:10.1371/journal.pone.0096317

Jun-Juan Feng, Liang-Wei Cui + Show 4 more

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https://doi.org/10.1371/journal.pone.0096317

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Journal: PloS one	Publication Date: May 2, 2014
Citations: 57	License type: CC BY 4.0

Affiliation: Southwest Forestry University, Dali University

Abstract

Vocal individuality and stability has been used to conduct population surveys, monitor population dynamics, and detect dispersal patterns in avian studies. To our knowledge, it has never been used in these kinds of studies among primates. The cao vit gibbon is a critically endangered species with only one small population living in a karst forest along China-Vietnam border. Due to the difficult karst terrain, an international border, long life history, and similarity in male morphology, detailed monitoring of population dynamics and dispersal patterns are not possible using traditional observation methods. In this paper, we test individuality and stability in male songs of cao vit gibbons. We then discuss the possibility of using vocal individuality for population surveys and monitoring population dynamics and dispersal patterns. Significant individuality of vocalization was detected in all 9 males, and the correct rate of individual identification yielded by discriminant function analysis using a subset of variables was satisfactory (>90%). Vocal stability over 2–6 years was also documented in 4 males. Several characters of cao vit gibbons allowed long-term population monitoring using vocal recordings in both China and Vietnam: 1) regular loud calls, 2) strong individuality and stability in male songs, 3) stable territories, and 4) long male tenure. During the course of this research, we also observed one male replacement (confirmed by vocal analysis). This time- and labor-saving method might be the most effective way to detect dispersal patterns in this transboundary population.

Highlights

Vocal communication is very common in birds, primates, and cetaceans that are living in dense forest or under water where olfactory and visual signals are limited or not feasible
Vocal Individuality Of the 41 variables analyzed, 27, 30, and 26 variables were selected to classify phrases of individuals in 3 separate discriminant function analysis (DFA), and 19 variables were repeatedly selected by all 3 discriminant functions (Table 3)
We provide the first demonstration of vocal individuality and stability in male songs of cao vit gibbons

Summary

Introduction

Vocal communication is very common in birds, primates, and cetaceans that are living in dense forest or under water where olfactory and visual signals are limited or not feasible. Arboreal, territorial apes, inhabiting the broad-leaved evergreen forests of Southeast Asia. They typically live in small groups comprised of one adult pair and 2–3 offspring [12]. All gibbons produce species-specific and sex-specific songs lasting 10–30 min in the early morning, and paired mates often combine their respective vocalizations into well-coordinated duets (with the exceptions of Hylobates klossii and H. moloch) [13,14]. Acoustic individuality has already been reported in several gibbon species: Hylobates agilis [1,3], H. klossii [18], H. moloch [19,20] and N. concolor [21], the vocal stability of gibbon songs has seldom been assessed (but see Fan et al [22])

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