The Biology of the Vole Clethrionomys rufocanus: A Review

The biology of the gray-sided vole Clethrionomys rufocanus in Hokkaido, concerning taxonomy, morphology, phylogeny, distribution, and natural history, is reviewed. Applied issues in forest management (damage, control and census) are also mentioned. Although Clethrionomys rufocanus of Hokkaido was originally identified as a distinct species, Evotomys ( = now Clethrionomys) bedfordiae Thomas, 1905, current literature generally refers to the gray-sided vole of Hokkaido as Clethrionomys rufocanus or as C. rufocanus bedfordiae (vernacular name, the Bedford's red-backed vole). The gray-sided vole is the most common small mammal in Hokkaido. It inhabits open areas as well as forests, and mainly feeds on green plants. The gray-sided vole has a high reproductive potential; litter size: 4-7; gestation period: 18-19 days; maturation age: 30-60 days old. Although spring-born individuals usually attain sexual maturity in their summer/fall of birth, their maturation is sometimes suppressed under high densities. The breeding season is generally from April to October, but with some regional variation. Clethrionomys rufocanus has a rather specialized diet (folivorous), particularly during winter when it feeds on bamboo grass. Many predators specialize on the grey-sided vole in Hokkaido; even the red fox, which is a typical generalist predator, selectively feeds on this vole. Damage by voles' eating bark used to be sever on forest plantations in Hokkaido. Censuses of small rodents have been carried out for management purpose since 1954.