Mating systems, such as monogamous and promiscuous mating, can be inferred by assess- ing social behavior, particularly pair bonding. We used partner preference tests to infer pair bond for- mation in three captive vole species from Eurasia and Japan, i.e. Microtus arvalis, M. montebelli, and M. levis. In all three species, females exhibited a preference for their male partners, but no preference was observed by males for their female partners. These results suggest that the social system of these vole species is non-monogamous.
