63.

Lemming Mountain Vole

Aschizomys lemminus

French: Campagnol lemming / German: Lemming-Gebirgswiihimaus / Spanish: Topillo de montana lemming

Other common names: Lemming Vole

Taxonomy. Aschizomys lemminus G. S. Miller, 1899, “Kelsey Station, Plover Bay, Bering Strait, [Chukotskiy], Siberia [Russia].”

In the past, A. lemminus was frequently classified as a species of Alticola or a subspecies of Myodes macrotis (as Alticola macrotis or Aschizomys macrotis). Monotypic.

Distribution. E Siberia and Russian Far East (E of Lena River and Yablonoi Mts E to Chukchi Peninsula).

Descriptive notes. Head-body 88-

120 mm,tail 10-28 mm; weight 21-39 g. Lemming Mountain Vole is small relative to species of Alticola . Tail is 16-24% of head-body length, is densely covered with hair, and has distinct tuft; it is distinctly bicolor, blackish brown above and gray below. Summer pelage is ash gray washed brown, belly is whitish gray, and demarcation on flanks is distinct. In most populations, winter pelage is whitish, washed cream, brownish on head. Northern populations are whiter than southern populations. Spring molt occurs from April to early July, autumn molt in September—October. Skull is small, semi-circular, and delicate. Molars resemble condition in Myodes rather than in Alticola . Enamelis thick, accumulation of cement is modest, and angles are rounded. Molars are hypsodont and rootless.

Habitat. Accumulations of rocks and talus slopes covered by mosses and lichens and surrounded by grasses, sage ( Artemisia, Asteraceae), and shrubs from sea level to elevations of ¢.2000 m. Rocks of moderate size are preferred over large boulders or small stones.

Food and Feeding. Diet mainly contains lichens ( Cetraria, Parmelia, Thamnolia, Alectoria, and Cladonia), followed by (in declining importance) mosses, berries ( Rubus, Rosaceae and Vaccinium, Ericaceae), leaves, flowers and grass seeds, pine seeds, invertebrates and fruits. In Yakutia (= Sakha Republic), no less than 59 flowering plants were identified in the diet. Most frequently consumed are alpine bearberry (Arctous alpina, Ericaceae), arctic and alpine wormwood ( Artemisia arctica and A. glomerata), shortstalk sedge ( Carex podocarpa, Cyperaceae), avens ( Dryas, Rosaceae), fescue ( Festuca, Poaceae), common woodrush ( Luzula multiflora, Juncaceae), locoweeds ( Oxytropis, Fabaceae), crimsontipped lousewort ( Pedicularis oederi, Orobanchaceae), oneflower cinquefoil ( Potentilla uniflora, Rosaceae), snow buttercup ( Ranunculus nivalis, Ranunculaceae), Kamtchatka rhododendron ( Rhododendron camtschaticum, Ericaceae), ivy ( Salix, Salicaceae), and ragwort ( Senecio tundricola, Asteraceae). To reach feeding grounds, Lemming Mountain Voles can travel up to 100 m from nests. Small amount of food can be stored in burrow. Stomach contents weigh 700-2800 mg (i.e. 6:2% of body weight).

Breeding. Reproduction at low elevations starts in May and lags by 15-20 days at high elevations;it lasts until August. In the south (e.g. Kolyma uplands), females have two litters in a season but a single one in the north (e.g. northern Yakutia and Chukotka); third litter is exceptional. In Russian Far East, reproductive activity peaks in June. Numbers of embryos per female are 3-9, averaging 4-5-5 near Olyokma River to seven in the Kharaulakhskiy Mountains. It is estimated that females have 5-3-6-4 young/season (mean 5-8). In the south, young females can mature in theirfirst year and have a single litter.

Activity patterns. The Lemming Mountain Vole is polyphasic. It dwells among rocks but also digs short burrows (20-30 cm). Nests of grass have diameters of ¢.15 cm. During winter, nests can be constructed under snow.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List (as Alticola lemminus). Overall distribution of the Lemming Mountain Vole is ¢.2,000,000 km?.

Bibliography. Chernjavskij (1984), Krivosheev (1984), Revin (1989), Shenbrot & Krasnov (2005), Tavrovskiy et al. (1971), Yudin et al. (1976).