Responses of Redfronted Lemurs to Experimentally Modified Alarm Calls: Evidence for Urgency-Based Changes in Call Structure

By Claudia Fichtel, K. Hammerschmidt. 2002

88 citations recorded by the source corpus.

The aim of this study was to investigate how information about the affective state is expressed in vocalizations. Alarm calls can serve as model systems with which to study this general question. Therefore, we examined the information content of terrestrial predator alarm calls of redfronted lemurs (Eulemur fulvus rufus), group-living Malagasy primates. Redfronted lemurs give specific alarm calls only towards raptors, whereas calls given in response to terrestrial predators (woofs) are also used in other situations characterized by high arousal. Woofs may therefore have the potential to express the perceived risk of a given threat. In order to examine whether different levels of arousal are expressed in call structure, we analysed woofs given during inter-group encounters or in response to playbacks of a barking dog, assuming that animals engaged in inter-group encounters experience higher arousal than during the playbacks of dog barks. A multivariate acoustic analysis revealed that calls given during group encounters were characterized by higher frequencies than calls given in response to playbacks of dog barks. In order to examine whether this change in call structure is salient to conspecifics, we conducted playback experiments with woofs, modified in either amplitude or frequencies. Playbacks of calls with increased frequency or amplitude elicited a longer orienting response, suggesting that different levels of arousal are expressed in call structure and provide meaningful information for listeners. In conclusion, the results of our study indicate that the information about the sender's affective state is expressed in the structure of vocalizations.

Subfields: Developmental Biology, Ecology, Evolution, Behavior and Systematics, Social Psychology

View Paper: https://www.semanticscholar.org/paper/ecd0de6a38b06e4a1882dfdc85a18401c2b2b2e1

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Citations in the corpus

Vocal Expression of Emotions in Mammals: Mechanisms of Production and Evidence (2012, unknown): “…5, 16, 17, 18, 20, 21, 24 Gouzoules & Gouzoules (1989) 39 Redfronted lemur Eulemur fulvus rufus A E/D E/O Alarm vocalizations 12, 15, 16, 18, 20, 22 Fichtel & Hammerschmidt (2002) 40 Squirrel monkey Saimiri sciureus A D E Alarm vocalizations 12, 15, 16 Fichtel & Hammerschmidt (2003) 41 A/V E E…”
Vocal Repertoire of Cebus capucinus: Acoustic Structure, Context, and Usage (2008, background): “The studies have shown that during more aversive situations, calls exhibit more nonharmonic energy, increased duration, increased frequency range, and higher frequencies at which the maximum amplitude was reached in the power spectrum (peak frequency; Fichtel and Hammerschmidt 2002, 2003).”
What makes a cry a cry? A review of infant distress vocalizations (2012, background): “, from semi-distressful short-term isolation to highly-distressful capture) (Fichtel and Hammerschmidt, 2002; Mendl et al., 2010).”
Chapter 8 Survivor Signals (2009, background): “Altering the frequency or amplitude of the calls generated differences in the orienting response of receivers, demonstrating that individuals attended to these features (Fichtel and Hammerschmidt, 2002).”