180.

Tian Shan Vole

Microtus ilaeus

French: Campagnol du Kazakhstan / German: Tienschan-Feldmaus / Spanish: Topillo de Tian Shan

Other common names: Kazakhstan ole

Taxonomy. Microtus ilaeus Thomas, 1912, “Djarkent, Semiretschensk [= Semirechyia], E. Russian Turkestan [= E Kazakhstan]. ‘On the banks of the River Ussek.’”

Microtus ilaeus is in subgenus Microtus . In the past, it was synonymized with #ranscaspicus or arvalis . It was also reported under the name kirgisorum, a junior synonym. Microtus ilaeus is sister species to all other species in subgenus Microtus . Two subspecies recognized.

Subspecies and Distribution.

M.i.ilaeusThomas,1912—EUzbekistan,SKazakhstan,Kyrgyzstan,Tajikistan,andNWChina(Xinjiang).

M. i. igromovi M. N. Meyer et al., 1996 — lower reaches of Syr Darya River in S Kazakhstan (Kyzylorda Region) and Amu Darya River in NW Uzbekistan (Karakalpakstan).

Descriptive notes. Head—body 109-144 mm, tail 35-50 mm; weight 46-64 g ( ssp. ilaeus); head—body 115-150 mm, tail 36-56 mm; weight 36-59 mm ( ssp. igromovi). Of the two subspecies, igromouvi is, on average, larger, and males are larger than females; mean weights of three-month-old females and males are 25-6 g and 32-2 g, respectively. The Tian Shan Vole is a large member of subgenus Microtus, with tail ¢.35% of head-body length. There are six (exceptionally five) plantar tubercles, and females have four pairs of nipples. Pelage is dark brown, rarely washed buff; flanks are lighter; and belly is gray. Tail is indistinctly bicolored. Skull is essentially as in the Transcaspian Vole ( M. transcaspicus), with well constricted interorbital region and low sagittal crest. Teeth are as in the Transcaspian Vole, except that M? occasionally has an additional postero-lingual loop.

Habitat. Humid meadows in river valleys and along irrigation ditches, clearings in riparian forests, reed ( Poaceae) beds, thickets of willows ( Salix, Salicaceae) and tamarisk ( Tamarix, Tamaricaceae) at lower elevations and juniper ( Juniperus, Cupressaceae) in subalpine pastures from lowlands on eastern side of the former Aral Sea at elevations of ¢.60 m up to 3200 m (mostly at 900-2000 m). Dependency of the Tian Shan Vole on proximity to water is particularly pronounced around the Aral Sea where it is exclusively tied to damp habitats along ditches and lakes that are densely overgrown with rushes ( Juncaceae), sedges ( Cyperaceae), and cattails ( Typhaceae). It also occurs in irrigated fields and orchards.

Food and Feeding. Spring diet of the Tian Shan Vole consists of green leaves and stems, bulbs, and seeds, with low proportions of insects and mushrooms. Seeds and fruits (e.g. berries and rose hips) are more important in autumn; bark andjuniper berries are eaten in winter. In Karakalpakstan, 25 plant species were identified in diets, including semiaquatic species, leaves and stems of reeds, cattails, rushes, and sedges. Underground plant parts are significant proportions in diets, and seeds are eaten to a lesser degree.

Breeding. Tian Shan Voles breed year-round in the Fergana Valley but seasonally elsewhere (i.e. April-June in mountains and April-November in Karakalpakstan). Litters have 1-10 young, and means vary seasonally between 3-6 and 4-3. Captive litters average 2-9 young.

Activity patterns. Daily activity is crepuscular. Tian Shan Voles excavate burrow systems, with up to 20 exits, 3-5 cm in diameter, exceptionally 8 cm. Tunnels are narrower and 2.2-5 cm in diameter; they are 5-11 cm underground, rarely up to 60 cm. Burrows usually contain 2-3 chambers, 7-16 cm in diameter. Nest chamberis lined with dry grass. Winter nests are constructed under snow; they are larger and consist of solid outer layer and inner layer of soft plant material.

Movements, Home range and Social organization. Tian Shan Voles live in family groups that frequently merge into small colonies. Same burrows are used for years. Galleries of different colonies usually persist isolated from each other.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Recently, population decline of the Tian Shan Vole was reported near the Aral Sea as a result of increase desertification and shrinking of riparian forests and reed beds.

Bibliography. Ayzin (1979), Davydov (1964), Golenishchev (2016a), Gromov & Erbajeva (1995), Meyeretal. (1996), Mahmoudi et al. (2017), Shenbrot & Krasnov (2005).