121.

Root Vole

Alexandromys oeconomus

French: Campagnol nordique / German: Nordische Wiihimaus / Spanish: Topillo de tundra

Other common names: Tundra Vole

Taxonomy. Mus oeconomus Pallas, 1776, Ishim River valley, Tyumen’ Region, Russia.

Alexandromys oeconomus was sometimes classified in subgenus Pallasiinus, which does not conform to requirements of the International Code for Zoological Nomenclature and is therefore an unavailable name. The correct subgeneric name is Oecomicrotus named by G. Rabeder in 1981. Genetically, A. oeconomus is close to A. kikuchii and A. montebelli . Within A. oeconomus, there are four distinct mtDNA clades: Central European (southern Scandinavia, Netherlands, Poland, Lithuania, Hungary, and south-western Slovakia), North European (northern and eastern Scandinavia, Belarus, and European Russia), Central Asian (Siberia and western part of Russian Far East), and Beringian (Chukchi and Kamchatka peninsulas, Kuril Islands, Alaska, and western Canada). Twentyfive subspecies recognized.

Subspecies and Distribution.

A.o.oeconomusPallas,1776—W&SCSiberia(Russia)andNWMongolia.

A.o.amakensisMurie,1930—AmakI(AleutianIs,Alaska).

A.o.arenicoladeSélys-Longchamps,1841—Netherlands.

A.o.dauricusKastschenko,1910—SCSiberia(areasaroundLakeBaikal)andNEMongolia..0.elymocetesOsgood,1906—MontagueI(SAlaska).app.0.finmarchicusSiivonen,1967—AndgyaandLanggyaintheVesteralenIs(Norway)..0.innwitusMerriam,1900—St.LawrenceI(Alaska)..0.kamtschaticusPallas,1779—KamchatkaPeninsula.Peep.0.kharanurensisCourantetal.,1999—GreatLakesHollow(NWMongolia).0.kjusjurensisKoljuschev,1935—NCSiberia..0.koreniG.M..Allen,1914—IndigirkaandKolymariverbasins(NEYakutia[=SakhaRepublic]andMagadanRegioninRussianFarEast).

A.o.macfarlaniMerriam,1900—NEAlaskaandNWCanada(Yukon,NorthwestTerritories,andNunavut).

A.o.mehelyiEhik,1928—SWSlovakia,EAustria,andHungary.

A.o.montiumcaelestinumOgnev,1944—DzungarianAlatauandTianShan(SEKazakhstanandNWChina)..0.operariusNelson,1893—W&SAlaska..0.popofensisMerriam,1900—UngaandPopofIs(AleutianIs,Alaska).Be.0.punukensisHall&Gilmore,1932—BigPunukI(Alaska)..0.ratticepsKeyserling&Blasius,1841—FennoscandiaandNEuropeanRussia..0.sitkensisMerriam,1897—ChichagofandBaranofIs(Alaska).

A.o.stimmingiNehring,1899—EGermany,Poland,Lithuania,Latvia,Belarus,Ukraine,andCEuropeanRussia.

A.o.suntaricusDukelsky,1928—NW,C&SYakutia.

A.o.tshuktshorumG.S.Miller,1899—ChukchiPeninsula.

A.o.uchidaeKuroda,1924—N&CKurilIs.

A.o.unalascensisMerriam,1897—Unalaska,UnimakandSanakIs(AleutianIs,Alaska).

A. o. yakutatensis Merriam, 1900 — SW Alaska and N British Columbia.

Also present on Kodiak I and small adjacentIs, and many other Aleutian Is, SW Alaska, but subspecies involved not known.

Descriptive notes. Head-body 79-150 mm, tail 28—60 mm, ear 8-21 mm, hindfoot 15-22 mm; weight 36-78 g. Male Root Voles are larger than females. Fur color of head and upperparts varies from dark chocolate-brown to light pale brown, underparts vary from brownish gray to ash-gray, and tail is bicolored. Sole of foot has six plantar pads. M? has four inner and 3-4 outer angles. Baculum has wide, diamond-shaped base; median process is slightly longer than lateral processes. Chromosomal complement is stable in most populations and has 2n = 30 and FN = 58; some populations of central Sweden and European part of Russia are polymorphic, with 2n = 30-32.

Habitat. Open, wet riparian habitats of tundra, boreal coniferous forest, mixed forest, forest steppe, steppe, and desert zones up to elevations of 2500-2900 m. In seasonally flooded habitats, the Root Vole seasonally shifts its habitat use to avoid flooding; when water table is low in late summer, autumn, and winter,it stays close to water depressions, but when water table is high due to ice and snow melting in spring and early summer, it moves to upperparts of lake depressions and river terraces.

Food and Feeding. In summer, Root Voles mainly eat green plant parts. In winter, main diet contains roots of sedges and grasses, berries, seeds, and bark of trees and shrubs; if available under snow, green shoots of plants are consumed. Root Voles store food for winter but only in habitats where green plants dry before it snows; winter food is not stored when green plant parts can be found under snow. Food is stored in special chambers in burrows; winter caches are 0.3-3 kg.

Breeding. Breeding of wild Root Voles was recorded in May—August in the north (tundra of Finland and Yakutia) and February-September in the south (mountains of Kazakhstan and Mongolia). Litters have 2-14 young; mean littersizes vary geographically from 4-5-5-4 in the south to 5-9-8-6 in the north. Gestation lasts 20-21 days. Overwintering females can produce 3-5 litters/year. Females born in spring—early summer are reproductively mature at 1-5 months old (sometimes 10-12 days) and can have 1-2 litters during their first year of life. Mating system of Root Voles is promiscuous, and multiple paternity has been recorded in 38% oflitters.

Activity patterns. In summer, Root Voles are usually more active during the day than night and around sunrise and sunset. Under snow in winter, activity is more or less evenly distributed throughout the 24hour cycle, with 5-10 activity bouts/24 hours (usually 6-7 hours); total duration ofactivity is 43-64% of the 24hour cycle, and duration of separate activity bouts varies from one minute to nine hours.

Movements, Home range and Social organization. Recorded movements of Root Voles were usually 20-200 m; in one case, movement of 3 km was recorded. Daily movements are 10-215 m in summer and 5-80 m in winter for adult males, 20-150 m (usually 30-50) for adult females, and 5-50 m for juveniles. Spatial organization of populations is quite variable. Adult females tend to be territorial in summer, and their home ranges are isolated or marginally overlap; home ranges of adult males widely overlap with other males and several females. Less often, individuals in monogamous pairs with completely overlapping home ranges are isolated from home ranges of other monogamous pairs and other individuals. In some cases, yearling sexually mature females form a cluster of overlapping home ranges that is monopolized by an adult male. Mean sizes of home ranges from different studies were 113-1087 m? for adult females and 210-3896 m* for adult males. Home range sizes of adult males positively correlate with body weights. In winter, Root Voles form colonies of 8-10 individuals of one or both sexes commonly using the area. Home range is organized around the nest burrow. Summer burrows are inside hummocks in wet habitats and in flat places in drier habitats. Summer burrows are shallow (just below the ground’s surface) and simple and have a nest chamber (10-15 cm in diameter) and 1-2 tunnels leading from the nest toward entrances. In extremely wet conditions and under snow, Root Voles build aboveground nests on tops of hummocks. Winter burrows are more complex and have several nest and storage chambers. Nest burrows or aboveground nests are connected to foraging sites and simple emergence burrows by pathways. Root Voles are relatively peaceful; more than one-half of pair interactions are neutral, and aggressive interactions are recorded in only one-third of encounters, even between unfamiliar individuals. Contacts among individuals are accompanied by acoustic communication expressed in quiet or sharp squeals and male songs.

Status and Conservation. Classified as Least Concern on The IUCN Red List (as Microtus oeconomus). Central European subspecies arenicola and mehelyi are endangered because of decreasing and fragmented habitat due to agricultural transformation, and need special conservation attention. North American island subspecies (amakensus, elymocetes, innuitus, popofensis, punukensis, sitkensis, and unalascensis) are regarded as being of conservation concern.

Bibliography. Abramson & Lissovsky (2012), Abramson & Tikhonova (2005), Bal¢iauskas (2014), BalCiauskas, Balgiauskiené & Baltranaité (2010), BalCiauskas, Baléiauskiené & Janonyté (2012), Bal€iauskiené & Baliauskas (2011), Bannikov (1954), Bannikova et al. (2010), Baskevich et al. (2014), Borkowska et al. (2009), Borowski (2001), Brunhoff, Galbreath et al. (2003), Brunhoff, Yoccoz et al. (2006), Frank & Zimmermann (1956), Fredga & Bergstrom (1970), Galbreath & Cook (2004), Gliwicz (1997), Gliwicz & Dabrowski (2008), Glotov et al. (1978), Gromov & Erbajeva (1995), Gubanyi et al. (2009), Hall (1981), Halle (1995), Haring et al. (2011), Ivankina (1974), Jancewicz et al. (2015), Korslund (2006), Lambin et al. (1992), Lissovsky & Obolenskaya (2011), Litvin (1980), Meyer et al. (1996), Mitchell-Jones et al. (1999), Rabeder (1981), Rutovskaya (2015), Shenbrot & Krasnov (2005), Shvetsov et al. (1984), Sludskiy et al. (1978), Tast (1966), Tavrovskiy et al. (1971), Thissen et al. (2015), Viitala (1994), Yudin et al. (1976), Zhang Yongzu et al. (1997).