Species Guide: Water Vole (Arvicola amphibius)
Family: Cricetidae
The Water Vole, often called the European or common water vole, is a semi-aquatic rodent native to much of Europe and parts of western Asia. It is best known for living along banks of rivers, streams, ditches, ponds, and wetlands, where it digs burrows, grazes on bankside vegetation, and swims with ease. The species has experienced steep declines in parts of its range (particularly Great Britain) largely because of habitat loss, watercourse modification, and predation by the introduced American mink.
Appearance
Water voles are compact, stocky rodents with thick fur and a blunt muzzle. Key identification points: short, rounded ears partly hidden in the fur; a furry tail (unlike the scaly tail of a rat); and dark brown to greyish fur on the back with a paler belly. Adults measure roughly 14–22 cm (body length) with tails about 9.5–14 cm long; weights commonly range from ~150–300 g, though larger individuals have been recorded. Their dense fur and body shape make them excellent swimmers.
Diet
Water voles are primarily herbivorous. They feed on a wide variety of riverside plants — grasses, sedges, shoots, stems, leaves, roots, rhizomes, bulbs, and occasionally tree bark. Studies and field guides report that water voles may eat hundreds of plant species and need to consume a large proportion of their body weight each day to meet energy needs. Very occasionally, they may take small invertebrates, molluscs, or aquatic plant material, but animal prey is not an important part of their diet.
Habitat
Water voles favour vegetated banks of slow-moving water: rivers, streams, drainage ditches, ponds, canals, marshes, and wet meadows. They excavate burrows into soft, often steep banks with entrances both above and below the waterline, and create feeding platforms and runways through waterside vegetation. Good bank vegetation for cover and abundant bank-side food are critical; degraded banks, heavy grazing, or engineered stone banks reduce suitability.
Behavior
Behavior & social structure: Water voles are mostly crepuscular and diurnal in calm areas (active during daylight hours), although activity patterns vary. Individuals defend small territories and use latrine sites and scent from flank glands to mark areas. They are adept swimmers and can dive and escape predators by entering water and using underwater entrances to burrows.
Reproduction & life cycle: Breeding typically runs from spring into autumn (often March–October), with females able to produce several litters a year. Gestation is short (about 20–21 days) and litters commonly contain 3–8 young. Young are born furred and with eyes open or opening within days, are weaned at around 3–4 weeks, and can reach sexual maturity in a few months. Lifespan in the wild is generally short; many individuals live under two years, although some survive longer.
Biometrics
Representative biometric values reported in field studies and species accounts: adult body length typically 140–220 mm (14–22 cm), tail length ~95–140 mm (9.5–14 cm), and adult weight commonly 150–300 g (with average figures varying by region and season). Males tend to be slightly larger than females on average. Age at sexual maturity is often 2–4 months; average lifespan is short (around 0.5–2 years in many populations).
Natural Predators
Water voles face predation from a wide variety of species: native predators such as foxes, stoats, weasels, owls, herons, and birds of prey take voles, particularly where bankside cover is thin. The single greatest contributor to recent declines in parts of their range (notably Britain) is the introduced American mink (Neovison vison), which hunts both in water and on banks and is especially effective at catching water voles where vegetation cover is reduced. Domestic and feral cats may also take water voles locally.
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Conservation Status
Status overview: Globally, the species is assessed under the name Arvicola amphibius and has a different conservation status across its wide range. In Great Britain, the water vole has suffered one of the steepest mammal declines recorded: large range contractions and population drops occurred in the late 20th century, and national assessments have flagged it as of conservation concern. Key threats and causes:
Fragmentation and small population effects: As populations shrink and fragment, local extinctions increase because recolonization is less likely and genetic problems can arise. Conservation actions and recovery: conservation organizations and statutory agencies manage mink control, restore riverside habitat (re-vegetation, soft engineering of banks), create habitat corridors, and run reintroduction projects where appropriate. Legislative protection and targeted local conservation efforts have helped some populations recover where sustained action occurs.
Predation by invasive American mink: The arrival and spread of American mink in Europe, especially the UK, is widely cited as the major factor driving rapid local extinctions because mink efficiently hunt water voles in both water and on banks.
Habitat loss and degradation: Riverside development, channelisation, bank hardening, intensive grazing, drainage of wetlands, and pollution reduce or fragment suitable bankside vegetation. Even where water remains, loss of dense cover leaves voles exposed to predators.
U.K.
Conservation Status
Global
Conservation Status
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References
- Brzeziński, M. et al. (2018) ‘An invasive predator affects habitat use by native prey: American mink and water vole co‐existence in riparian habitats’, Journal of zoology (1987), 304(2), pp. 109–116. [Accessed 18/09/2025]
- Brace, S. et al. (2016) ‘The colonization history of British water vole (Arvicola amphibius (Linnaeus, 1758)): origins and development of the Celtic fringe’, Proceedings of the Royal Society. B, Biological sciences, 283(1829), p. 20160130. [Accessed 18/09/2025]
CITATIONS
- By Nordelch – Own work, CC BY-SA 3.0 [Accessed 05/10/2025] ↩︎
