Event:

Inspired by Darwin (1872), mammalian vocalizations are suggested to encode the internal emotional state of a sender. While some support exists for vocal cross-taxa similarities in the expression of arousal, an increasing number of studies reveal a more complex pattern. Testing Mongolian gerbil pups in two contexts assumed to induce different arousal levels demonstrated arousal-dependent changes that varied with the pups’ developmental stage. Playback experiments showed that both parents respond significantly stronger to pup vocalizations than to a 10 kHz control sound, with stronger response to calls produced in high- versus low arousal contexts. Additionally, adult gerbils combine non-vocal acoustic displays (drumming) with vocalizations. Drumming is suggested to signal an increased arousal state of the sender, whereas the accompanying call type conveys context-specific information. Playback experiments supported this, showing that gerbils immediately escape in response to drumming’s but approach the loudspeaker in response to alarm calls. However, in predator experiments only 54% of the drumming’s were accompanied by alarm calls suggesting an individual arousal dependent threshold. Correlating personality tests with vocalization-induced behavioural paradigms indicated that bold individuals produced more alarm calls than shy individuals. To sum up, Mongolian gerbils’ exhibit arousal- and development-dependent vocal and non-vocal displays, with personality correlated to acoustic behaviour, suggesting that vocalizations reflect the sender’s arousal state.