Similar acoustic structure and behavioural context of vocalizations produced by male and female California mice in the wild

Ultrasonic vocalizations (USV) are an important part of multimodal communication in mice; however, nothing is known about the behavioural context of USV production by individual mice in the wild. Using remote-sensing methods we recorded USVs from individual adult free-living Peromyscus californicus. Because adult male and female P. californicus share duties in rearing offspring and defending territories, we predicted that male and female P. californicus would produce USVs in similar behavioural contexts and with similar spectral and temporal characteristics. We found that adult male and female P. californicus produced USVs, with the most common motifs being one-, two- and three-syllable vocalizations. USVs of males and females did not differ significantly in type or number, or in spectral or temporal characteristics. Peromyscus californicus produced USVs when alone and when they were with another mouse, and the three-syllable vocalization (3SV) motif, which has a relatively long first syllable, was more likely to be produced in the presence of another mouse than when a mouse was alone. The likelihood of vocalizing and the spectral and temporal characteristics of vocalizations did not differ when an individual was producing a USV in the presence of a mate or nonmate. Males and females produced USVs in the same behavioural contexts. Thus, as with other behaviours associated with parenting and territorial defence in P. californicus, USVs of males and females are produced in similar behavioural contexts and have similar spectral and temporal characteristics.

► We used remote-sensing techniques to record ultrasound from individual free-living rodents in the wild.
► We analysed ultrasonic vocalizations of Peromyscus californicus, a monogamous muroid rodent.
► Adult male and female mice produced ultrasound.
► Patterns of ultrasound production were similar between males and females.
► Spectral characteristics of ultrasound were similar between males and females.