The individual context of ultrasonic vocalizations in wild monogamous California mice (Peromyscus californicus).

Ultrasonic vocalizations (USVs) are commonly produced by the rodent species in the Super Family Muroidea. The bulk of USV research has been conducted on Mus and Rattus exclusively in a laboratory setting. There is variation in the production and function of USVs between Mus and Rattus as a result of contrasting social structures. Peromyscus californicus is an obligately monogamous species that regularly produces USVs. The objective of my study is to determine the context of USV production in free living P. californicus in California. I investigated motif use and spectral and temporal characteristics of USV as they related to sex, and estrous state. I determined when pairs produced USVs as well as the individuals present when USVs were produced. I looked at the production of USVs in response to sub-adult dispersal and I compared the variation between pairs with the variation within pairs. The most commonly recorded USV motifs were 1-4 syllable vocalizations. Sex and estrous state were independent of motif type and the spectral characteristics of USVs did not differ between males and females or estrous and non-estrous females. Pairs never vocalized when they were in contact and motif type was independent of individuals present on the focal area. The majority of USVs were recorded during the breeding season, however, USV production was highly positively correlated with sub-adult dispersal (Pearson’s correlation 0.79). While I did not find a difference between pairs or individuals within a pair, my analysis suggests that the difference between pairs is more significant than the difference between individuals within a pair. My results suggest USVs reinforce pairbonds and advertise a pair’s territory. Peromyscus californicus is an excellent model for monogamy in mammals and USVs are an important component of P. californicus behavior in the wild