Ultrasonic courtship vocalizations in wild house mice, Mus musculus musculus

Adult house mice produce ultrasonic vocalizations (USVs) that are sexually dimorphic and have features of song. To test whether USVs play a role in sexual courtship, we examined how males produce USVs following exposure to scent from conspecifics of different sexes and ages, and also femalesʹ attraction to recorded playbacks of malesʹ USVs. We studied wild-derived house mice (F1 from wild-caught Mus musculus musculus) since previous work has almost exclusively been on domesticated strains. Males produced USVs in response to female but not to male or immature female urinary scent, and males responded at a higher rate to urine from novel than familiar females. Malesʹ prior social experience had no effect on their USV responses to fresh female urine, corroborating studies with laboratory mice. When presented with playbacks, females were more attracted to USVs of novel males, and showed a preference for unfamiliar nonkin versus familiar siblings. Our results support the idea that male USVs function as courtship behaviour to attract mates, and extend several previous findings on laboratory strains to wild house mice. We also show that USVs are highly diverse among males, but further experiments are needed to determine whether these vocalizations play a role in social (individual, sibling or kin) recognition, inbreeding avoidance or other forms of mate choice.