Many small predators rely on bank voles as prey. Bank voles partially escape predation by remaining under cover in underground tunnels or runways in grass and vegetation. I is thought that avian predators use the ultraviolet reflections of scent marks to locate their prey (Koivula et al. 1999).
Known Predators:
Adult bank voles reach a head-body length of 10-11cm and a weight of 17-20g, with males and females being approximately the same size. The tail is less than body length and reaches a length of 3-4cm. Bank voles are small with small eyes and ears. Their body is covered by thick fur in shades of brown or gray. Their muzzle is blunt and rounded. Relative to body size, M. glareolus has a small brain. Teeth are prismatic and are characterized by flat crowns, which are adapted for their herbivorous diet (Macdonald 2001).
Range mass: 17 to 20 g.
Range length: 10 to 11 cm.
Other Physical Features: endothermic ; bilateral symmetry
The lifespan of M. glareolus is very short. Average lifespan is 0.5-2 years, with most individuals not lasting more than one breeding season (Macdonald 2001; Ostfeld 1985). Bank voles mature quickly with females maturing at 2-3 weeks and males maturing at 6-8 weeks (Macdonald 2001).
Range lifespan
Status: wild: 0.5 to 2 years.
Typical lifespan
Status: wild: 0.5 to 2 years.
Bank voles are found in a wide variety of habitats, including forests, scrub forests, hedges, banks, and swamps (Macdonald 2001; Bellamy et al. 2000). They appear to prefer deciduous, coniferous, and taiga forests (Yoccoz et al. 2001; Prevot-Julliard et al. 1999; Koskela et al. 1998; Koskela et al. 1997; Ostfeld 1985).
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: taiga ; forest
Wetlands: swamp
Other Habitat Features: agricultural ; riparian
There is a rich fossil record in the Pleistocene (Macdonald 2001).
Perception Channels: tactile ; chemical
Bank voles are widely distributed and often abundant, they are not threatened.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Myodes glareolus have been found to spread hantavirus. In temperate climates, they are also crop pests (Macdonald 2001).
Humans benefit from bank voles through their beneficial ecosystem roles.
Bank voles are important as a prey base for many small avian and mammalian predators and snakes. They are often abundant and can form the main component of the diet of these predators. They may also help in recycling and redistributing nutrients in the ecosystems in which they live through herbivory.
Myodes glareolus have been characterized as omnivorous (Ostfeld 1985) and herbivorous (Macdonald 2001). When eating grass, M. glareolus clip the stalks and lays the clippings in piles. Food is obtained in the winter by burrowing underground. In the summer and fall food is cached. Diet changes with season and location but includes green parts of plants (Macdonald 2001), fruits and seeds from available trees, such as the European ash tree (Fraxinus excelsior) (Flowerdew and Gardner 1978) and grass (Macdonald 2001).
Plant Foods: leaves; seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Folivore , Frugivore , Granivore )
Palearctic: Myodes glareolus is found from Europe through Central Asia (Macdonald 2001; Jonsson et al. 2000). Populations have frequently been recorded in Finland (Oksanen et al. 2001; Yoccoz et al. 2001; Oksanen et al. 1999; Prevot-Julliard et al. 1999; Horne and Ylonen 1996, 1998; Koskela et al. 1998; Koskela et al. 1997) and the United Kingdom (Bellamy et al. 2000; Flowerdew and Gardner 1978).
Biogeographic Regions: palearctic (Native )
The mating system of M. glareolus can be described as polygamous (Macdonald 2001), and possibly promiscuous (Horne and Ylonen 1998). While females defend territories that may overlap with other females, males defend larger territories that overlap with the territories of several females. Females appear to prefer dominant males and may affect which males get the chance to mate by running away from subordinate males (Horne and Ylonen 1998). As parturition nears, females become more aggressive and each female's territory decreases in size. The home range becomes smaller and the central ranges of different territories become farther from each other (Koskela et al. 1997).
Mating System: polygynous ; polygynandrous (promiscuous)
The estrous cycle of M. glareolus lasts four days (Oksanen et al. 1999). The breeding season is from late April to September (Oksanen et al. 2001). Copulation is characterized by a series of intromissions followed by ejaculation (Horne and Ylonen 1996). Gestation lasts from 17 days with optimal nutrition, to 24 days if the female becomes pregnant while lactating during postpartum estrus (Macdonald 2001; Koskela et al. 1998). The average gestation length is 21 days (Macdonald 2001). From 1 to 10 pups are born per litter with approximately 4 litters born per breeding season (Macdonald 2001; Oksanen et al. 2001). The average number of pups per litter is 4-8 (Oksanen et al. 2001). Pups weigh 1-10g at birth, which makes up a total of 22-28% of the female’s weight. During pregnancy and lactation, females require 30-130% more energy (Ostfeld 1985). Infanticide occurs in males and females. Females will kill the pups of their female neighbors and males will kill pups as a mating tactic (Koskela et al. 1998; Koskela et al. 1997; Horne and Ylonen 1996).
Breeding season: Breeding occurs from April to September.
Range number of offspring: 1 to 10.
Average number of offspring: 4-8.
Range gestation period: 17 to 24 days.
Average gestation period: 21 days.
Range weaning age: 20 to 25 days.
Range age at sexual or reproductive maturity (female): 2 to 8 weeks.
Average age at sexual or reproductive maturity (female): 3-6 weeks.
Range age at sexual or reproductive maturity (male): 2 to 8 weeks.
Average age at sexual or reproductive maturity (male): 3-6 weeks.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Pups are born blind and helpless in an underground nest lined with grass and other vegetation. The female is the sole provider of parental care (Macdonald 2001). The pups are weaned at the age of 20-25 days (Macdonald 2001; Oksanen et al. 2001; Oksanen et al. 1999; Horne and Ylonen 1998).
Parental Investment: altricial ; female parental care
The bank vole (Clethrionomys glareolus) is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around 100 millimetres (3.9 in) in length. The bank vole is found in much of Europe and in northwestern Asia. It is native to Great Britain but not to Ireland, where it has been accidentally introduced, and has now colonised much of the south and southwest.
The bank vole lives in woodland, hedgerows and other dense vegetation such as bracken and bramble. Its underground chamber is lined with moss, feathers and vegetable fibre and contains a store of food. It can live for eighteen months to two years in the wild and over 42 months in captivity and is mostly herbivorous, eating buds, bark, seeds, nuts, leaves and fruits and occasionally insects and other small invertebrates. It readily climbs into scrub and low branches of trees although it is not as versatile as a mouse. It breeds in shallow burrows, the female rearing about four litters of pups during the summer.
The bank vole is a small rodent resembling a mouse when young but developing a stouter body, a slightly rounder head with smaller ears and eyes and a shorter, hairy tail. The dorsal surface is reddish-brown, with a greyish undercoat and the flanks are grey with a reddish-brown sheen. The underparts are whitish-grey sometimes tinged with dull yellow. The ears are larger than those of most voles. The adult head and body length varies between 3.25 and 4.75 inches (83 and 121 mm) and the tail ranges from 1.5 to 3 inches (38 to 76 mm). The weight is between 15.4 and 36 grams (0.54 and 1.27 oz). Young animals are darker in colour with greyer underparts. The bank vole is capable of making growling sounds and can utter low-pitched squeaks.[2] In a case of distress and isolation it has been witnessed to emit a sound resembling that of a human sob.
In areas such as Great Britain, where the only other small vole is the short-tailed vole (Clethrionomys agrestis), the bank vole is distinguished by its more prominent ears, chestnut-brown fur and longer tail which is usually 50% body length. The northern red-backed vole (Clethrionomys rutilus) from northern Scandinavia and Russia, has a shorter tail and is paler with less grey in its pelage. The grey red-backed vole (Clethrionomys rufocanus) from northern Eurasia, is larger with a distinctive reddish back.[2]
The bank vole has a Palearctic distribution. It is native to Europe, Asia Minor and parts of Western Siberia. It does not occur in Iceland or northern Fenno-Scandia (except for Finland) and is absent from most of the Iberian Peninsula and parts of Italy and the Balkans.[2] It was introduced into southwestern Ireland in the 1950s, and there are fears that it may be displacing the native wood mouse (Apodemus sylvaticus). A subspecies found on the island of Skomer in West Wales, the Skomer vole (Myodes glareolus skomerensis), is much larger than the mainland bank vole, and there may be 20,000 individuals on the island in late summer.[3]
The bank vole is found in forests, especially in deciduous and mixed woodland with scrub, low plants and leaf litter. It is also present in hedgerows, field verges, among bracken and brambles, river banks, swamps and parks. In mountainous regions and the northern part of its range it occurs in coniferous woodland at altitudes of up to 1,800 metres (5,900 ft). It is not found on bare soil and ample ground cover seems a necessity.[2] In the Mediterranean region, at the southern extent of its range, it is a habitat specialist and is found in moist woodland but not in grassland and bushy places.[4] At the fringes of forested areas it is possible for there to be a metapopulation consisting of a number of spatially separated populations of bank vole that come and go according to the season and local events. Some areas may be devoid of voles during the winter and be repopulated during the summer only to become empty of voles again in October. The further from permanently inhabited forest the location is, the fewer females there are and the more widely the number of individuals fluctuates.[5]
The bank vole is active by day and also at night. It does not hibernate in winter. It excavates long, shallow branching burrows with multiple exits, sometimes tunnelling along beneath the leaf litter. It gathers and stores food underground and makes a nest with moss, dry grasses and leaves close to the surface or even above ground. It is in general quite bold but is also very alert to the cries of other animals such as tits (bird) warning of aerial predators.[2]
The bank vole is primarily a herbivore. Its diet varies with the season but usually consists of leaves, grasses, roots, buds, bark, fruits, nuts, grain and seeds. When feeding on grass stalks it may clip the stalks and lay the cut pieces in piles. Some food is carried back to the burrow where it is kept in dedicated storage chambers. It sometimes eats animal food in the form of insects, spiders and worms and may take eggs from the nests of birds nesting on the ground.[2][6]
The bank vole climbs well and in the winter it feeds on the bark of trees including beeches, maples and larch up to several metres above the ground. It also eats tree seedlings and reduces the natural regeneration of woodland and when present in large numbers, is considered a forest pest. However, its harmfulness is relatively low in a healthy ecosystem because significant damage only occurs when numbers build up, and because it has a large number of natural enemies its population is normally kept under control.[7]
Females are typically larger than males, but male-bias sexual dimorphism occurs in alpine populations, possibly because of the lack of predators and greater competition between males.[8]
Females maintain territories which may overlap somewhat, and males occupy larger territories covering those of several females. The home range of females is usually between 500 and 2,000 square metres (5,400 and 21,500 sq ft).[9] The breeding season lasts from late April to September. Females appear to prefer dominant males and may actively avoid other vagrant males. The gestation period averages 21 days, being longer if the female is still lactating from a previous litter. A litter can be up to ten pups but the average number is four to eight. Females sometimes kill pups in burrows in adjoining territories and males sometimes kill pups before mating with their mother, perhaps as a tactic to ensure his offspring are advantaged. The pups are naked and helpless and their eyes open at about nine days. They are weaned at 20 to 25 days and the females become sexually mature by six weeks with the males reaching maturity by eight weeks. There may be up to four litters per year and as the youngsters start to breed, numbers quickly build up over the summer months. The bank vole lives for up to two years in the wild.[6] In captivity this can increase to over 42 months, with the older voles tending to spend most time resting, less physically agile, though still capable of having a spin on the wheel.
The bank vole is plentiful during much of the year and plays an important part in the diet of various predators including the red fox (Vulpes vulpes), the stoat (Mustela erminea), the least weasel (Mustela nivalis), the European mink (Mustela lutreola), the common kestrel (Falco tinnunculus), the rough-legged buzzard (Buteo lagopus) and the tawny owl (Strix aluco). The voles try to prevent being caught by avoiding open areas of ground, by using tunnels and well-worn paths through the undergrowth.[6]
The bank vole acts as a reservoir of infection for the Puumala virus, which can infect humans, causing a haemorrhagic fever known as nephropathia epidemica and, in extreme cases, even death.[10] Although this hantavirus has co-evolved with its host, its presence among populations seems to decrease their over-winter survival rates.[11]
The bank vole has a very wide range across Europe and western Asia. The population density depends on the time of year and location and varies between six and one hundred individuals per hectare. The population size varies from year to year but in the long term appears to be stable. For these reasons, the International Union for Conservation of Nature has rated the bank vole as being of "Least Concern" in its Red List of Threatened Species.[1] When it lives on road verges, the bank vole can suffer from lead toxicity and near farmland it may be affected by pesticides, molluscicides and rodenticides.[12]
The bank vole (Clethrionomys glareolus) is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around 100 millimetres (3.9 in) in length. The bank vole is found in much of Europe and in northwestern Asia. It is native to Great Britain but not to Ireland, where it has been accidentally introduced, and has now colonised much of the south and southwest.
The bank vole lives in woodland, hedgerows and other dense vegetation such as bracken and bramble. Its underground chamber is lined with moss, feathers and vegetable fibre and contains a store of food. It can live for eighteen months to two years in the wild and over 42 months in captivity and is mostly herbivorous, eating buds, bark, seeds, nuts, leaves and fruits and occasionally insects and other small invertebrates. It readily climbs into scrub and low branches of trees although it is not as versatile as a mouse. It breeds in shallow burrows, the female rearing about four litters of pups during the summer.
