Shikotan Vole

Shikotan vole is an endemic species of the Pacific island ridge, primarily Shikotan ^[3] . It occurs on about. Sakhalin (the extreme south), on the island of Shikotan (where the name comes from) and Kunashir , from the Lesser Kuril ridge - on about. Green , also noted on about. Hokkaido and the adjacent fairly large archipelago of the islands of Rebun and Risiri , as well as on a small island. Daikoku ^[4] . On the northwestern edge of its range (Schmidt Peninsula on Sakhalin Island), the Shikotan vole is a rather small species with sporadic distribution. More severe wintering conditions on Sakhalin, apparently, explain the fact that the Shikotan voles from Sakhalin are slightly inferior in terms of skull and body to voles of the same species from Shikotan ^[4] .

Shikotan

In the territory of the Russian Federation, this species of voles is numerous only on about. Shikotan . Although the Shikotan vole lives throughout the island, its concentration in different types of biotopes is different. The species prefers sparse stone-birch bamboo forests, as well as the outskirts of grassy bogs, where vagina cannabis , sundew , cranberries , rosemary and trifol grow . It actively colonizes river valleys overgrown with willow and alder, especially where there are cereal and mixed grass meadows , as well as thickets of Kuril bamboo. Much less often than Shikotan voles can be observed in yew-spruce-fir forests with an admixture of broad-leaved species. Sometimes found in thickets of juniper, which occupies the tops of hills. The species is also recorded on the Morx coast, in particular where coastal sands and sea terraces have been mastered by high cereal grasses, sedges, interspersed with rosehips and creeping molokans. The habitats of the Shikotan vole may coincide with the habitats of the red-gray vole. However, the first species prefers open clarified areas with bamboo bush among individual forest inclusions, as well as willow-alder thickets along floodplain areas of river valleys and streams, while red-gray voles gravitate towards closed and darkened yew-spruce-fir forests ^{[ 5]} . According to research, in Shikotan itself, red-gray voles prevail over Shikotan in the catch of most biotypes in the proportions of 67-87%. The exception is willow-alder thickets and spruce-fir forests, where the share of the Shikotan vole reaches 76% and 55%, respectively. The predominance of red-gray voles over the Shikotan voles is also due to their greater fecundity. So, red-gray voles begin breeding already in late April, and Shikotan voles only by mid-May. As a result, adult Shikotan voles bring only 2 litters per year, in red-gray voles - up to 3. The breeding season in both species usually ends by mid-October ^[6] .

Brown-brown color of fur prevails. The tail is well-pubescent, one-color or slightly two-color. Like all voles, it is relatively short (no more than 65 mm) with a body length of up to 150 mm. The fur on the back is short, stiff, brown in color with an admixture of dark rusty red hair; the sides are dark, smoky gray; fur on the abdominal surface is painted in light gray tones. From the smaller gray voles, the Shikotans differ primarily in their larger sizes. Compared with the Sakhalin vole, the Shikotan vole has a longer densely pubescent tail, which reaches almost half the body length, and not a third.

The Shikotan vole is characterized by a polyphase type of daily activity. It feeds almost exclusively on plant foods (stems, underground shoots and rhizomes). Nests are usually built in bumps or simple burrows, from which it makes paths to feeding places. The places of her feeding can often be determined by piles of pieces of plant stems 8-10 cm long. It is also noteworthy that in a number of their habitats the Shikotan vole actually occupied an ecological niche of the genus of gray voles. As a result, some models of behavior of this species have become more characteristic of representatives of the genus Microtus than of the genus Clethrionomys . Among them, the presence of colonial settlements, a change in the nature of digging activities, the emergence of new methods of nutrition and food storage. In the process of reproduction, only adult overwintered individuals are involved. It begins in the second half of May - early June. The average number of embryos varies within a narrow range from 6.7 to 7.3 (an average of 7.2) ^[5] .

• Serbenyuk M.A., Galanina T.M. Maintenance and breeding of Shikotan voles ( Clethrionomys sikotanensis ) // First All-Union Conference on Zooculture Problems. Abstracts of reports. Part two. Moscow, 1986, pp. 247-249.