- Latin name
- Myodes glareolus
- Class
- Mammals
- Group
- Mice, Voles & Shrews
The Bank vole at a glance
Size: Head and body length between 8-12 cm (3-5 in.) with tail no longer than half that (up to 7 cm / 2.7 in.). Wide range of adult weight according to habitat such that adults can weigh 14-40 grams (0.5-1.4 oz.), although typically 18-20 g (0.6-0.7 oz.). Island races tend to be larger than mainland animals.
Colour/Appearance: Reddish-chestnut brown fur, often greyer on flanks, with a silver-grey to whitish stomach; juveniles tend to be greyer than adults. Some populations (e.g., in Hampshire) exhibit very dark, almost black, fur. The eyes are small and black, nose pink and surrounded by long whiskers, and ears are small but broad, only just taller than surrounding fur. The tail is short tail.
Distribution: Found throughout Europe and central Asia, as far north as northern Finland, east into eastern Russia, and south into the Mediterranean, although absent from Portugal and all but northern reaches of Spain. Present throughout England, Wales, and Scotland, although distribution is patchy in the far north and west. Found in Listowel, County Kerry in the Republic of Ireland during 1964, having apparently been deliberately introduced (possibly from Germany as early as 1920s) and now established in south-west of the country.
Habitat: Inhabits wide range of habitats including woodland (deciduous, mature coniferous and, in Europe, taiga), mixed farmland, and scrub. Sometimes found in fenland and bogs, although generally seems to prefer drier areas. Also found in areas with high herb growth, banks and hedges such as railway embankments, road verges, riverbanks, parkland and sometimes rural gardens. Their requirement for fairly dense ground cover makes them less common in city gardens than wood mice.
Longevity: Survival to their second winter is rare, with the oldest individuals probably reaching only 18-21 months. One animal of unknown sex kept in captivity at London zoo in the early 1900s died just short of 5 yrs.
Sexing: Impossible to determine sex without handling and, even then, the anal-genital distance not necessarily accurate method. One study of Mediterranean voles found anywhere from 15-100% of males were mis-sexed based on external anatomy vs. molecular analysis.
Activity: Active by day and night, although dawn and dusk peaks and more diurnal during winter. Voles often seem to exhibit a 2-6 hour activity rhythm. Voles do not hibernate and during periods of heavy snow cover they remain active in subnivean zone, moving around in a series of tunnels and pockets under the snow. Voles move with a quick "darting" run, readily distinguishable from the hop of the wood mouse, and can climb well (males particularly) to reach fruit and seeds. Bank voles may move comparatively large distances, covering several hundred metres; 930 m (0.6 mi.) recorded for males during breeding season.
Territory/Home Range: Size varies widely according to habitat, age, sex, and season, ranging from ca. 380 to 7,300 sq-m (0.09-1.8 acre); ca. 1,400 sq-m (0.35 acre) seems typical in deciduous woodland. Female ranges are exclusive during breeding season but overlap outside of this, while those of males are larger and overlap with both sexes year-round. Females may allow daughters to live, but not breed, in their home range. Defence of territory has been documented in captivity, but seems rare in the wild where mutual avoidance appears to prevail. A largely sedentary species that's highly faithful to a given site (especially females) with a strong homing ability up to ca. 700m (0.4 mi.) outside their home range. Creates a shallow subterranean nest with a radiating tunnel network leading to multiple entrances, often among tree roots or under logs. The nest is ball-shaped and composed of locally available materials, particularly grass, leaves, and moss.
Diet and Feeding: Primarily herbivorous with 40-50% of the diet being green leaf matter; a smaller proportion of seed, fruit, and animal matter. Dead leaves are eaten, usually during winter, while fungi, roots, flowers, buds, grass, moss and invertebrates (especially insects, earthworms, and slugs) are taken occasionally. Food may be cached (stored) under logs, in leaf litter, and/or in tunnel walls. Seeds sometimes carried away in "false cheek pouches", although voles generally feed where the food is found; on the ground, in their burrow system, or in trees/bushes. Digestion is high efficient and vole gut anatomy changes to adapt to variations in diet.
Reproduction: Breeding season in most of UK runs from March/April to September/October, shorter and more intense on some northern islands, but this can be protracted by bountiful food and mild temperatures. Bank voles are induced ovulators and females are highly fertile after the first pregnancy. Breeding nests are built either in their existing burrow system or sometimes tree holes. Litters typically consist of 3-5 (max. 8) pups, each weighing about 2 g (0.07 oz.), born after a 16-20 day gestation. Young will leave the nest for short periods/excursions from around 15 days old. Lactation lasts 17-18 days, at which point pups weaned and weigh ca. 10g (0.35 oz.). Multiple paternity is common, with one Polish study finding ca. 25% litters had two or more fathers. Parental care is provided by female alone, and are pups sexually mature at around 5 wks, although late born pups may not mature until the following spring. Most won't breed until about 8 wks old.
Behaviour and Sociality: A broadly gregarious with apparent dominance hierarchy that affects mating chances in males. Scent is pivotal in vole society and voles appear able to distinguish individuals of their own race/subspecies (e.g., mainland vs. Skomer) based on odour alone. Females recognise the scent of their mate and prefer it over that of unfamiliar individuals. High pitched vocalisations made during aggressive encounters and courtship, with experienced males apparently vocalising more then inexperienced ones. Respond to bird alarm calls by increasing vigilance.
Predators: Have wide range of predators including cats, foxes, badgers, stoats, weasels, martens, adders, kestrels, buzzards, corvids, and owls. Barn and tawny owls are probably their most significant avian predators in Britain.
Threats: An abundant and adaptable species that is not considered threatened, or granted any specific protection in Britain. Data from motorway verge populations suggest the species is susceptible to lead poisoning and agricultural chemicals.
Bibliography
Atlas of the Mammals of Great Britain & Northern Ireland - by Multiple Contributors
Pelagic Publishing
-- 2020
-- ISBN: 978-1784272043
Britain’s Mammals 2018: The Mammal Society’s Guide to their Population & Conservation Status - by Multiple Contributors
The Mammal Society
-- 2020
-- ISBN: 978-0993567339
Collins Field Guide: Mammals of Britain and Europe - by David MacDonald and Priscilla Barrett
HarperCollins Publishers
-- 1993
-- ISBN: 978-0002197793
Fauna Britannica - by Stefan Buczacki
Hamlyn Publishing
-- 2002
-- ISBN: 978-0600598671
Mammals of the British Isles: Handbook, 4th Edition - by Stephen Harris and Derek Yalden (eds)
The Mammal Society
-- 2008
-- ISBN: 978-0906282656
The natural history "bible" covering all British mammals with detailed coverage of their biology, behaviour, ecology and taxonomy written by experts in the field and referenced to the primary literature.
The Encyclopaedia of Mammals - by David MacDonald (ed.)
Brown Reference Group
-- 2006
-- ISBN: 978-0199206087
The New Amateur Naturalist - by Nick Baker
HarperCollins Publishers
-- 2004
-- ISBN: 978-0007157310
UK Mammals: Species Status & Population Trends - by The Tracking Mammals Partnership
JNCC/TMP
-- 2005
-- ISBN: 978-1861075680
Urban Mammals: A Concise Guide - by David Wembridge
Whittet Books
-- 2012
-- ISBN: 978-1873580851