Production of ultrasonic vocalizations by Peromyscus mice in the wild.
BACKGROUND
There has been considerable research on rodent ultrasound in the laboratory and these sounds have been well quantified and characterized. Despite the value of research on ultrasound produced by mice in the lab, it is unclear if, and when, these sounds are produced in the wild, and how they function in natural habitats.


RESULTS
We have made the first recordings of ultrasonic vocalizations produced by two free-living species of mice in the genus Peromyscus (P. californicus and P. boylii) on long term study grids in California. Over 6 nights, we recorded 65 unique ultrasonic vocalization phrases from Peromyscus. The ultrasonic vocalizations we recorded represent 7 different motifs. Within each motif, there was considerable variation in the acoustic characteristics suggesting individual and contextual variation in the production of ultrasound by these species.


CONCLUSIONS
The discovery of the production of ultrasonic vocalizations by Peromyscus in the wild highlights an underappreciated component in the behavior of these model organisms. The ability to examine the production of ultrasonic vocalizations in the wild offers excellent opportunities to test hypotheses regarding the function of ultrasound produced by rodents in a natural context.
Kalcounis-Rueppell
Matina C
MC
Department of Biology, University of North Carolina at Greensboro, 1000 Spring Garden Street, Greensboro, North Carolina, USA.
Metheny
Jackie D
JD
Department of Biology, University of North Carolina at Greensboro, 1000 Spring Garden Street, Greensboro, North Carolina, USA.
Vonhof
Maarten J
MJ
Department of Biological Sciences, Western Michigan University, 1903 W. Michigan Avenue, Kalamazoo, Michigan, USA.