Vocal recognition of partners by female prairie voles

Abstract

Recognizing conspecifics is vitally important for differentiating kin, mates, offspring and social threats. Although often reliant upon chemical or visual cues, individual recognition across the animal kingdom is also facilitated by unique acoustic signatures in vocalizations. However, amongst the large Muroidea superfamily of rodents that encompasses laboratory species amenable to neurobiological studies, there is scant behavioral evidence for individual vocal recognition despite individual acoustic variation. Playback studies have found evidence for coarse communicative functions like mate attraction and territorial defense, but limited finer ability to discriminate known individuals' vocalizations. Such a capacity would be adaptive for species that form lifelong pair bonds requiring partner identification across timescales, distances and sensory modalities, so to improve the chance of finding individual vocal recognition in a Muroid rodent, we investigated vocal communication in the prairie vole (Microtus ochrogaster) - one of the few socially monogamous mammals. We found that the ultrasonic vocalizations of adult prairie voles can communicate individual identity. Even though the vocalizations of individual males change after cohabitating with a female to form a bond, acoustic variation across individuals is greater than within an individual so that vocalizations of different males in a common context are identifiable above chance. Critically, females behaviorally discriminate their partner's vocalizations over a stranger's, even if emitted to another stimulus female. These results establish the acoustic and behavioral foundation for individual vocal recognition in prairie voles, where neurobiological tools enable future studies revealing its causal neural mechanisms.