REPRODUCTIVE AND BEHAVIORAL BIOLOGY OF THE GRAY-TAILED VOLE

We describe the reproductive biology of the gray-tailed vole, Microtus canicaudus, and relate behavioral and morphological features to the mating system. The breeding season extended from March through December, mean litter size was 4.4 young, and hip (scent) glands were prominent in adult males and females throughout the breeding season. Juvenile dispersal was male-biased, and home ranges of opposite-sex relatives did not overlap when juveniles became reproductively active. Gray-tailed voles were sexually dimorphic, and males had larger home ranges than did females, indicative of a polygynous or promiscuous mating system. However, males had relatively small testes, which is characteristics of monogamy or single-male harems. We conclude that the mating system of gray-tailed voles cannot be inferred from behavioral and morphological correlates, as has been attempted for other species of Microtus.