Vocal behavior of the Mongolian gerbil in a seminatural enclosure

This study represents the first effort to obtain a comprehensive library of adult Mongolian gerbil (Men ones unguiculatus) vocalizations recorded in a variety of behavioural contexts. In Phase I of the study, a gerbil colony was introduced into a seminatural enclosure and allowed to breed naturally over an observation period of 19 months. During this period, detailed observations of gerbil social and vocal behaviour were made. In Phase 11, this knowledge was used to stage natural behavioural scenarios among adult gerbils in which high-quality recordings of vocalizations could be obtained, and the spectro-temporal properties of these vocalizations analysed. Calls generally occurred in interactive social situations, such as same-sex aggression, mating, food dispute, alarm, and disturbance by conspecifics. Additionally, brief ultrasonic calls were associated with investigation of a new setting and were named 'contact calls'. Vocalizations were classified by behavioural context and analysed with respect to spectral and temporal characteristics. Calls encompassed a broad range of frequencies (approx. 3-45 kHz); most calls possessed significant energy at two or more harmonics in addition to the fundamental frequency. Calls generally lasted approx. 4-500 ms and were emitted in sequences of 3-20 variants with silent intervals. Such natural call series had significant low-frequency AM content below 8 Hz. Calls within an individual behavioural class had substantial variability in both spectral and temporal properties, but were significantly different from all other call classes in one or more of average fundamental frequency, frequency sweep range, duration, or frequency sweep direction.