Growth, Development, and Reproductive Patterns in the Japanese Field Vole, Microtus montebelli

Abstract

We describe characteristics related to the reproductive biology of the Japanese field vole, Microtus montebelli. In comparison with the other species of Microtus examined to date, Japanese field voles grew more rapidly and exhibited the most male-biased sexual dimorphism, with males having relatively small testes, indicative of a polygynous mating system. Thus, we conclude that this species is polygynous, possibly with the type of facultatively monogamous mating in which species show social patterns that combine elements of several systems.