Bank Vole

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. 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 (Microtus 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 (C. rutilus) from northern Scandinavia and Russia has a shorter tail and is paler with less grey in its pelage. The grey red-backed vole (Craseomys rufocanus) from northern Eurasia is larger with a distinctive reddish back.

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. 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 (C. g. skomerensis), is much larger than the mainland bank vole, and there may be 20,000 individuals on the island in late summer.

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. 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. 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. When present in large numbers, it is considered a forest pest. …