The biology of the voleClethrionomys rufocanus: A review

Abstract

Abstract. The biology of the gray-sided vole Clethrionomys rujocanus 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 rujocanus of Hokkaido was originally identified as a distinct species, Evotomys (=now Clethrionomys) bedjordiae Thomas, 1905, current literature generally refers to the gray-sided vole of Hokkaido as Clethrionomys rujocanus or as C. rujocanus bedjordiae (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 rujocanus 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.

The role of vole populations in prevalence of the parasite (Echinococcus multilocularis) in foxes

“…Since 1954 the Hokkaido government has carried out a incentive program for private foresters to census voles for pest management (Kaneko et al 1998). Since the same year the Forestry Agency of the Japanese government has also carried out similar censuses in national forests all over Hokkaido (see Saitoh et al 1997Saitoh et al , 1998b for details of census methods).…”

“…Of these two potential sources of data, we used the census data from private natural forests investigated by designated, trained specialists, because most private forests are near suburban or cultivated areas, and therefore offer suitable habitats for red foxes. In contrast most national forests are located in mountainous areas (Kaneko et al 1998). The trappings were carried out at 18 sites in Abashiri, at three sites in Nemuro, and at nine sites in Kushiro.…”

So, what do we know and what do we need to know more about the population ecology of the voleClethrionomys rufocanus?

“…6. General life history of C. rufocanus is well known in Hokkaido: basic information about the breeding season, gestation period, litter size, maturation age, food habits, habitats and interspecific relationships are available (Kaneko et al 1998; see also Ota 1984). Social organization (e.g.…”

“…Many other details of demography are also poorly known for C. rufocanus in Hokkaido (cf. Kaneko et al 1998;); in particular, we know essentially nothing about how demographic rates vary among regions with different dynamic behaviors. 8.…”

“…Unfortunately, this monitoring program faded out by 1995, as a result of changes in silviculture practices reducing the practical need for a continued monitoring program (see, e.g. Kaneko et al 1998). From a scientific point of view, this is unfortunate since a continuation of this monitoring program would have had an added-value-effect of each additional year far beyond the investments per each additional year.…”