Vocal cues to identity and relatedness in giant pandas (Ailuropoda melanoleuca)

Abstract

A range of acoustic characteristics typically carry information on individual identity in mammalian calls. In addition, physical similarities in vocal production anatomy among closely related individuals may result in similarities in the acoustic structure of vocalizations. Here, acoustic analyses based on source-filter theory were used to determine whether giant panda bleats are individually distinctive, to investigate the relative importance of different source-(larynx) and filter-(vocal tract) related acoustic features for coding individuality, and to test whether closely related individuals have similarities in call structure. The results revealed that giant panda bleats are highly individualized and indicate that source-related features, in particular, mean fundamental frequency, amplitude variation per second, and the mean extent of each amplitude modulation, contribute the most to vocal identity. In addition, although individual pairwise relatedness was not correlated with overall acoustic similarity, it was highly correlated with amplitude modulation rate and fundamental frequency range, suggesting that these acoustic features are heritable components of giant panda bleats that could be used as a measure of genetic relatedness. The ecological relevance of acoustically signaling information on caller identity and the potential practical implications for acoustic monitoring of population levels in this endangered species are discussed.

Distributional Limits and Melanism in the South-West of the Range of the Crowned Sifaka (Propithecus coronatus), Madagascar

“…The anatomy of the vocal tract influences the acoustic structure of vocalizations in a variety of species (Fitch 1997;Reby et al 2005;Gamba and Giacoma 2006;Charlton et al 2009). For example, in rhesus macaques (Macaca mulatta) formant frequency dispersion is correlated with vocal tract length and body size (Fitch 1997).…”

Vocal repertoire of free‐ranging adult golden snub‐nosed monkeys (Rhinopithecus roxellana)

“…According to many previous studies of other primates, the distances of ≤10 m should be an appropriate cutoff to obtain high quality recordings and measure acoustic parameters, especially in terms of those related to intensity (e.g., Macaca sylvanus : Hammerschmidt & Fischer, 1998; Papio papio : Maciej, Ndao, Hammerschmidt, & Fischer, 2013; Gorilla gorilla : Salmi & Doran‐Sheehy, 2014; Mandrillus sphinx : Levréro et al, 2015). For each selected recording, we used Praat to measure 16 temporal, spectral, and intensity parameters: duration, mean f 0 , SD f 0 , start f 0 , end f 0 , min f 0 , max f 0 , range f 0 , %T_min f 0 , %T_max f 0 , meanAMP, minAMP, maxAMP, rangeAMP, HNR, and Jitter (parameter definitions and extraction/calculation methods: Table 1) (Charlton, Zhihe, & Snyder, 2009a, 2009b). If vocalizations were uttered in bouts, we considered each call separately for analysis.…”

Vocal cues to male androgen levels in giant pandas

“…In particular, males 'bleat' at high rates during encounters with oestrous females [2], indicating a key role for these vocalizations in reproductive contexts. Recent work has shown that male giant panda bleats encode information on the caller's identity and body size [3,4]; however, male bleats may also contain information about a caller's hormonal quality that is highly relevant in reproductive contexts. For example, given that testosterone is an important component of male competitive ability and sperm quality in mammals [5,6], vocal cues to male androgen levels may be important in this species' sexual communication for intrasexual assessment or mate choice, respectively.…”

“…We had no a priori directional predictions for our measures of F 0 modulation. In addition, since male giant panda testosterone levels fluctuate during the breeding season [13] and the formants of giant panda bleats appear to be static components of these calls [4], we did not expect to find a relationship between male androgen levels and formant spacing.…”