101.

Narrow-headed Vole

Lasiopodomys gregalis

French: Campagnol gréle / German: Schmalkopf-Wiihimaus / Spanish: Topillo de cabeza estrecha

Other common names: Narrow-skulled Vole

Taxonomy. Mus gregalis Pallas, 1779, E of Chulym River, Novosibirsk Region, Russia.

Lasiopodomys gregalis is in subgenus Stenocranius. Morphologically and genetically, it is a sister species to L. raddei . In the past, it was placed in the genus Microtus . Within L. gregalis, there are three distinct mtDNA clades, north-western (northern, western, and central Siberia, Altai, and Tian Shan), central (Tuva), and south-eastern (south of eastern Siberia and northern Mongolia). The first clade is subdivided into six geographically distinct lineages: steppes of western Siberia, Yamal Peninsula and Northern Ural Mountains, northern Altai Mountains, southern Altai Mountains, Yakutia (= Sakha Republic), and Tian Shan. Phylogeographic structure reflects complex history of L. gregalis that includes a Middle Pleistocene dispersal from Altai region toward the north and south-west, followed by a wide distribution across tundra-steppe landscapes during most of the Pleistocene, and finally decrease and fragmentation of the distribution due to humidification of climate and a wide advance of tree vegetation at the Pleistocene— Holocene boundary. Geographical variation is expressed as a complex combination of clines and mosaic variability in size, color, and skull proportions. Eighteen forms of subspecific rank have been described, but they weakly reflect existing patterns of morphological and genetic variation. Subspecific taxonomy requires reassessment.

Distribution. Subdivided into several isolated patches of different size: N sections located along Arctic shore in Russia from Northern Dvina River E to Kolyma River (Arkhangelsk Region, Nenets Autonomous District, SE Novaya Zemlya, Vaygach I, Northern Ural Mts, Yamal Peninsula, Belyy I, S Taymyr Peninsula, and N Yakutia), C section includes C Yakutia, and S sections extend from Kama River E to Amur River and from S Siberia S to Tian Shan and interfluve of Huang He and Yangtze in E China including Russia, Kazakhstan, Kyrgyzstan, Mongolia, and China (NW Xinjiang, Inner Mongolia [= Nei Mongol], Heilongjiang, Hebei, and Henan).

Descriptive notes. Head—body 81-148 mm, tail 17-46 mm, ear 8-16 mm, hindfoot 12-21 mm; weight 18-68 g. Male Narrow-headed Volesare slightly larger than females. Fur of head and upperparts varies from relatively light ocherous brown to dark brownish gray; top of head and anterior back often have fuzzy longitudinal dark strip; underparts are dark gray to yellowish ocher; tail is bicolor, brown above and light below. Sole of foot has six plantar pads. Braincase is narrow. Auditory bullae are relatively small and not inflated. M? has four inner and three outer angles. M, has five alternating triangles; anterior triangles T6 and T7 are confluent and broadly integrated into anterior cup. Chromosomal complement has 2n = 36 and FN = 54.

Habitat. Tundra, forest-tundra, coniferous forest, forest steppe, steppe, semi-desert and desert zones, and mountain meadows up to elevations of 4200 m. In tundra, semidesert, and desert, Narrow-headed Voles prefer river valleys and lake depressions. In forests, they occur in open dry meadows.

Food and Feeding. Diet varies seasonally, but in every season, green parts of grasses, onions, and forbs are eaten. In late spring and summer,it feeds almost exclusively on green parts of plants; in early autumn, seeds, berries, fungi, and roots make up 7-10% of diet; and from late autumn to early spring, roots are 17-55% of diets. Lists of forage plants vary geographically and contain 22-94 species. In relatively rare cases, animal food (including small birds and rodents) is eaten. Food is stored for winter. Caches consist of dried green parts of plants, roots, bulbs, and seeds. Amounts are small in the steppe zone but can reach 2-5 kg/burrow in tundra and mountain meadows.

Breeding. Reproduction occurs in May-July in northern parts ofits distribution and April-October in southern parts, where it can even extend into winter. Litters have 2-15 young (averages 6-4-9-9). Adult females can produce 3-4 litters/year in the north and 4-5 litters in the south. Females become sexually mature at weights of 14— 16 g and can have 1-2 litters during the first year oftheir life.

Activity patterns. Activity patterns of Narrow-headed Voles vary seasonally. In spring, they are active round-the-clock, appearing aboveground in short bouts 100-200 times/ day; bouts last an average of 1-2 minutes during daylight and two minutes at night. In summer, they are more active at twilight, with four-minute activity bouts, and diurnals bouts of aboveground activity last 2-4 minutes every two hours. With decreasing temperatures in autumn, night activity decreases and daily activity increases to 15 minutes/bout.

Movements, Home range and Social organization. Narrow-headed Voles live in large family groups that occupy complex burrow systems; groups consist of 10-13 residents of different sex, age, and reproductive status. Within a family group, there are also several non-resident individuals. All individuals in a group are amicable, share a common nest, and help to rear offspring. Reproductive relations established in the group are stable. There is no inbreeding avoidance, and young males even prefersibling females as mating partners. Family burrows have several large nest chambers, 12-16 cm in diameter and c.12 cm deep in summer and 21 cm deep in winter. A burrow also contains several storage chambers and system of tunnels at depths of 7-9 cm. Burrow systems of average family groups cover 3-3-3-6 m? and have an average of 17 entrances. Larger burrows extending more than 1000 m* with 100-120 entrances were also recorded. Mean home ranges of males are 790 m? in spring, 1675 m* in summer, 625 m* in autumn, and 425 m? in winter; those of females are 380 m?, 1150 m?, 360 m?, and 400 m?, respectively. Home ranges partially overlap, and ¢.22% ofthe area is used commonly with other individuals. Contacts among individuals are accompanied by acoustic communication expressed as quiet or sharp squeals and male songs. Sharp squeals are usually emitted during aggressive interactions. Quiet squeals are usually emitted by males and females during friendly contacts. Songs are exclusively male signals that are emitted during courtship with females. Under emergency situations, Narrow-headed Voles produce alarm calls sitting at burrow entrances.

Status and Conservation. Classified as Least Concern on The IUCN Red List (as Microtus gregalis).

Bibliography. Abramson & Lissovsky (2012), Abramson, Lebedev, Tesakov & Bannikova (2009), Bannikov (1954), Gladkikh et al. (2016), Glotov et al. (1978), Gromov & Erbajeva (1995), Pal’chekh et al. (2003), Petrova, Tesakov et al. (2016), Petrova, Zakharov et al. (2015), Potapov et al. (2012), Rutovskaya & Nikolskiy (2014), Sludskiy et al. (1978), Tavrovskiy et al. (1971), Yanushevich et al. (1972), Yudin et al. (1979), Zadubrovskiy et al. (2016), Zhang Yongzu et al. (1997).