Living Organisms / Animalia / Craniata / Mammalia / Rodentia / Muridae / Arvicola / Species
Arvicola terrestris - European water vole (Click photographs/illustrations: full picture & further details)
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General and References

Alternative Names (Synonyms)

  • Water rat
  • Water vole
  • Campagnol terrestre (French)
  • Ostschermaus (German)
  • Schermaus (German)
  • Mus terrestris Linnaeus, 1758; Upsala, Sweden
  • Mus amphibius Linnaeus, 1758; England
  • Arvicola ater MacGillivray, 1832; Scotland
  • Arvicola amphibius amphibius (J42.81.w1).

Alternative species names (the second part of the binomial species names): [Genus] abrukensis; [Genus] albus; [Genus] americana;  [Genus] amphibius; [Genus] aquaticus; [Genus] argentoratensis; [Genus] argyropus; [Genus] armenius; [Genus] ater; [Genus] barabensis;  [Genus] brigantium; [Genus] buffonii; [Genus] cantabriae; [Genus] canus; [Genus] castaneus; [Genus] caucasicus; [Genus] cernjavskii;  [Genus] cubanensis; [Genus] destructor; [Genus] djukovi; [Genus] exitus; [Genus] ferrugineus; [Genus] fuliginosis; [Genus] hintoni;  [Genus] hyperryphaeus; [Genus] illyricus; [Genus] italicus; [Genus] jacutensis; [Genus] jenissijensis; [Genus] karatshaicus; [Genus] korabensis; [Genus] kuruski; [Genus] kuznetzovi; [Genus] littoralis; [Genus] martinoi; [Genus] meridionalis; [Genus] minor;  [Genus] monticola; [Genus] musignani; [Genus] niger; [Genus] nigricans; [Genus] obensis; [Genus] ognevi; [Genus] pallasii;  [Genus] persicus; [Genus] pertinax; [Genus] reta; [Genus] rufescens; [Genus] scherman; [Genus] seythius; [Genus] stankovici;  [Genus] tanaiticus; [Genus] tataricus; [Genus] tauricus; [Genus] turovi; [Genus] uralensis; [Genus] variabilis; [Genus] volgensis (B141).

Names for new-borns / juveniles

Names for males  
Names for females  

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General Appearance

Rat sized vole-type rodent, with blunt muzzle, small ears and tail approximately half of body length (B144, B155, D30).

Similar Species

  • Differentiated from Rattus norvegicus - Brown rat by darker fur, rounder body, blunter muzzle, smaller eyes, smaller ears mainly hidden in fur and shorter, haired tail.
  • Differentiated from other voles in Britain by much larger size.
  • Juveniles differentiated from field voles by larger head and feet, and longer tail.

(B142, B155, D30)

Sexual Dimorphism Minimal. Male about 5% larger than female and with longer but fewer guard hairs (B142, D30).

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Species Author

Debra Bourne

Major References

Husbandry references:

(UK Contacts)

(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

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TAXA Group (where information has been collated for an entire group on a modular basis)

Parent Group

  • Voles (Rodents)

Specific Needs Group referenced in Management Techniques

  • Voles (Rodents)

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Husbandry Information


Individual Techniques linked in Wildpro

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Appearance / Morphology

Measurement & Weight

Length Head-body length: 
  • 5.6-8.0in./14-20cm (B144); 120-260mm (D30).
  • Males 121-261mm; females 119-247mm (B142).
Height --
Adult weight General 2.5-11.4oz./70-320g (B144).
Male 246-386g, mean 311g (B142); 240-330g (B155).
Female 225-310g, mean 272g (B142); 225-310g (B155).
New-born weight 0.2oz/6g (B144); 3.5-7.5g (B142); about 5g (B147).
Growth rate
  • First litter of the year: 160g by 5 weeks old; second litter 160g by 12 weeks old (County Durham) (B142).
  • 42g at 3 weeks, 120g at about 3.5 months (B155).

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General --

Skull: Nuchal crest develops over first winter (B142).

Nose: Blunt.

Ears: Small.

(B142, B155)

Dentition (Teeth)
  • Upper incisors large, orthodont. Enamel on outer surface bright orange.
  • Molars high crowned and rootless - grow throughout life.

(B142, B147, B155)

Eyes Small, dark, protuberant (B142).

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Legs and Tracks

  • Four toes from fore feet tracks, five on hind feet (B142).
  • Hind Foot length: males 26-42mm, females 25-41mm (B142).

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  • Length 60% (55-70%) of head-body length. 
  • Lightly haired

(B142, B155, D30).

  • Length: 2.4-4in./6-10cm (B144); Males 82-174 mm, females 80-161mm (B142).

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Coat / Pelage

Adult Female
  • Dorsal: red-brown, medium-brown, dark brown or black. Grades to:
  • Ventral: paler: grey-white/brownish-white/greyish-ochre.
  • Long glossy guard hairs.

(B142, B155, D30)

Variations (If present)
  • Melanic form: proportion of individuals with black fur varies between populations: common in Scotland.
  • Partial albinism: (white patches), most often white patches on tail tip, forehead. Also occur on chest, front paws, flanks, shoulders.
  • Older animals: fur thin and greyish after second winter and no spring moult.

(B142, B147, B155)

  • Autumn moult (main moult) in adults and juveniles.
  • Spring moult after first winter.
  • No moult if survive second winter: fur becomes thin.

(B142, B147)

New-born / Juvenile Juveniles: guard hairs shorted and denser (B142).

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Neonate (New-born) Characteristics

Blind and helpless (B147B155).

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Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

  • Reproductive: Four pairs of nipples in females (B147).
  • Scent glands: flank glands in both sexes (B147)

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Life Stages / Natural Diet / Physiology

Reproductive Stages

Breeding Season
  • Males fecund from February.
  • First conceptions by females March/April.
  • Weaned juveniles seen June to October.

(B142, B155)

Oestrus / Ovulation
  • Polyoestrus.
  • Post-partum oestrus.
  • Oestrus suspended during lactation.
  • Oestrus suspended during winter (late August or September to Spring).

(B142, B155)

Gestation / Pregnancy
Parturition / Birth
  • April to September.
Neonatal development
  • Birth: blind, helpless; 
  • Eight days: eyes open
  • 14 days: weaned 


Litter size
  • 1-11, usually approximately 6 (B144); about 6 (B142).
  • 2-8, usually 4-6 (B147).
Time between Litters / Litters per year
  • Up to five litters per year, mean 3.4 (B142, B155); 1-4 litters per year (B147).
Lactation / Milk Production
Sexual Maturity
  • Two months (B144).
  • Mean 110g (60 days), minimum 77g (38 days).
  • Do not always breed in year of birth.

(B142, B155).

  • 2.5 years in wild, 3.5 years in captivity (B144).
  • Some survive second winter, very rarely survive third winter (B142, B155).
  • May reach five years old in captivity (B147).

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Natural Diet

Mainly vegetarian:
  • Green and subterranean parts of grasses and sedges, also tree roots and bark.
  • Grasses (Graminae), sedges (Cyperacae), Phragmites australis - common reed, and Ranunculus fluitans - river crowfoot) commonly eaten.
  • Grasses usually only growth meristem eaten, but whole of young shoots may be eaten.
  • Rushes and dicotyledons such as Urtica dioica - Nettle and Lamium album - Dead-nettle eaten less commonly.
  • Insects, molluscs (freshwater mussels and snails), fish (carrion) taken only exceptionally.
  • More reeds and rhizomes eaten by adults than by juveniles.
  • Fruits eaten in winter, with apple a preferred food
  • Tree roots, tree bark, herbaceous roots, bulbs and rhizomes eaten in winter.
  • Hay (kept green in burrows) also eaten in winter
  • Eat about 80% of body weight per day.

(B142, B143, B144, B147, B155)

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Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

Temperature --
Pulse --
Respiration --
  • 8-12mm long, cylindrical, blunt-ended, often greenish.
  • Left in latrines marking range boundaries and at water edge and near burrows.


Haematology / Biochemistry --
Chromosomes 2n = 36 in Britain; on continent some chromosome variation - FNa = 60=68 (B142).
Other --

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Feeding Behaviour

  • Feed while sitting on hind legs, holding food in forefeet.
  • Often leave piles of grass and reed stems when only nodes and stem bases eaten.
  • Harvest hay in autumn, keep in burrows for winter.

(B142, B155)

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Parental Behaviour


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Social Behaviour / Territoriality

Intra-specific Territory length approximately 64-640ft/20-200m, (B144).
  • Variations with season and population density.
  • Larger home ranges for males than females.
  • Smaller home ranges for juveniles, except for young males moving between females's territories.
  • Winter ranges smaller than breeding ranges
  • Communal nests in winter: female, daughters and unrelated males
  • Spring: fights, with losers dispersing.
  • Males fight more aggressively than do females.
  • Breeding females defend exclusive territory
  • Territory of breeding females marked with latrines, which mate then scent-marks
  • Males disperse by four months old, moving between territories of females, then settle.
  • Dominant daughters settle within territory, subordinate daughters disperse.
  • Adult females may disperse following fights with daughters (even while pregnant).
  • Males mark territories using flank gland secretions.
  • Populations may be 20-114 per kilometre along waterway (B155).

High population density differences:

  • Home ranges of males and females smaller.
  • Female home ranges overlapping and undefended.
  • Fewer fights between breeding females.
  • Less overlap between home ranges of males.

Fossorial populations:

  • Fluctuate 0-1000 individuals per hectare, in 5 to 8-year cycles.(B143); 46 year cycles (B147).

(B142, B143, B144, B147, B155)

Inter-specific --

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Sexual Behaviour

  • Females have only single mate throughout breeding season.
  • Male may have two or three mates during breeding season.
  • Some males have no mate.
  • Male grabs female by scruff during copulation

(B142, B155)

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Predation in Wild

Mammalian carnivores, various predatory birds, also Esox lucius - pike.

(B142, B155)

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Activity Patterns

  • Use runways, remembering direction of runway.
  • Good and frequent swimmer.
  • Dive well.
  • Jump well.
  • Juvenile males disperse on runways on land.
  • Juvenile females usually disperse by swimming.
  • Away from water, use burrow systems.
  • Able to climb in trees to feed.

(B142, B144, B155).

  • Active about every 2 to 4 hours.
  • More active in daytime in some areas.
  • Less active in middle of night on cold nights.
  • Less active in middle of day on hot days.
  • Out of nest about 25% of time over 24 hours, and longer (peaking at 38%) during breeding season.
  • Active all year, but spend more time in burrows in winter.

(B142, B155)

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Habitat and Range

General Habitat Type

Aquatic populations:
  • Mainly lowlands.
  • Densely vegetated ditch, dyke, river and stream banks, usually with slow currents and continuous presence of water.
  • Less common on ponds.
  • Require certain depth of water: do not use very shallow areas .
  • Also away from water, living mainly below ground in burrows.
  • N.B. Away from water more commonly in continental Europe than in Britain.

Fossorial populations:

  • Dry and mesic grasslands: meadows, pastures.
  • Occasionally wooded areas.

(B142, B143, B144, B147, B155)

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Nests / Burrows / Shelters

  • Make complex burrow systems.
  • Nest within burrow system.
  • If water table high, may nest in tussock sedges.
  • Sometimes plug exits from nursing chambers with loose soil or with grass.
  • Rarely build nests of large balls of reeds or grass above ground.
  • Burrow may average 40.2m long, with one or two nests, also with storage chambers in autumn and winter.


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Distribution and Movement (Migration etc.)

  • Palearctic: Great Britain to eastern Siberia (Lena Basin), and from Arctic circle to Lake Baikal, north of Aral Sea, northern Iran, Near East.
  • In Britain: Throughout mainland Britain, and on Bute, Anglesea, Isle of Wight.
  • Not present: Ireland, western and southern France, southern Iberian peninsula, southern Greece.
  • Not found at very high altitudes in Alps.


Some populations migrate, e.g.:

  • a population in north-west Scotland, wintering on higher ground.
  • German and Russian populations, seasonally moving from wet to dry habitats.

(B51, B142, B143, B155)

Occasional and Accidental --


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Intraspecific variation

  • Large number of subspecies described (at least 36).
  • Polymorphic.
  • Aquatic populations larger (150-300g) and more commonly dark furred.
  • Fossorial populations smaller (60-150g), more commonly pale furred and with incisors more protruding. Found in Carpathians, Alps, Massif Central, Pyrénées, north of Spain, north of Portugal.


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Conservation Status

Wild Population -
  • Under threat in western Europe: Britain, Italy, Netherlands.
  • In Britain: disappeared from 70% of sites by 1993, and decline continuing (B155, D30, V.w30)
  • Fossorial populations may cause agricultural damage at high densities (B147).
  • In Britain: native, and declining but still moderately common (1995). Pre-breeding population estimate of about 1169,000, with 752,000 in England, 376,000 in Scotland, 41,000 in Wales. Population estimate of this widely-distributed species was based on a limited amount of data and considered likely to be inaccurate by up to 50% in either direction (B221).
General Legislation
  • This species is listed on Schedule 5 (Protected animals) of the LUK2 - Wildlife and Countryside Act 1981 of the United Kingdom. (W5.Oct01) (Section - 9(4)(a) and (b) "damaging etc. a place used for shelter" and disturbing an animal while occupying a structure or place of shelter" only)
CITES listing --
Red-data book listing --
Threats Predation by Mustela vison - American mink, water pollution, loss of habitat (B143, B147, B221).
Captive Populations --
Trade --

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