Bank Vole (Evotomys glareolus, Schreber).
There can be little doubt that in many places the Bank Vole has been mistaken for a bright variation of the Field Vole. Its habits are much the same, except that it haunts the hedgerow and wooded country rather than the open fields. As to the differences between the two species, the Bank Vole's head and body measurement is only three and three-quarter inches against four inches in the Field Vole, but its tail is actually (not merely proportionately) longer, being nearly half the length of head and body, and ends in a pencil of hairs. The ears and feet are proportionately larger, the former also being more oval than round. It further differs from the other Voles in the fact that the molar teeth become rooted in the jaws of the adults. The fur of the upper parts is a bright chestnut-red or Vandyke brown, excepting the hairy tail, which is black above. The under parts, including the lower side of the tail, are whitish varying to yellowish or even buff. The redder tint causes this species frequently to be styled the Red Vole. It has pink lips, and grey feet. Whiskers about an inch long. Black and albino varieties have been recorded.
It was considered formerly to be a rare British species, but more discriminating attention to the smaller mammals in recent years, and the wider adoption of trapping by naturalists, have tended to modify that view. It is probably more local, but it appears to be widely distributed, and to occur as far north certainly as Moray and Elgin; but it is not recorded from Ireland, Man, Hebrides, or Shetland. A local race is found in Skomer Island, and has been named E. skomerensis. When Yarrell detected the Bank Vole as a distinct species in 1832, it was considered to be of very restricted range in this country. The discovery was made in Essex, but it was soon reported from Herefordshire, Middlesex, Berks, and Cambridge, and more recently from Oxfordshire, Warwickshire, Shropshire, Worcestershire, the Lake District, Northumberland, Inverness, etc. It is restricted to Europe in its wider range. In this country it does not appear to occur at elevations of more than about 700 feet.
The Bank Vole is much more agile than the Field Vole, and not so much given to burrowing. It may be seen abroad in sunny situations at any time of the day, preferring warm, dry places, yet frequently to be found in wet places. It is a good swimmer and diver. It constructs shallow runs in the earth of a roadside bank or hedgebank. These have many entrances and exits above and below, as shown in our photograph; some of the passages connecting with the top of the bank, others enlarging into blind chambers. Its food includes herbage, roots, bulbs, fruits, and seeds; it appears to be particularly fond of turnips. In spring it has been observed climbing rose and hawthorn bushes in order to nibble the new leaves, and in autumn to obtain the hips and haws. It also seeks nuts, berries, the grain of wheat and barley, and the seeds of smaller grasses. Insects, snails, and even small birds are eaten by it, and the entrance to its burrows frequently gives evidence of the variety of its food. It has been known to eat the unpalatable Shrew that it has killed, and even to given way to cannibalism. In Scotland it is accused of eating the shoot-buds of young conifers, especially of larch, and gnawing the bark from branches.
In this country it is occasionally captured in the act of robbing household stores, but in more northern regions, as in Norway and the Yukon, it is a constant inhabitant of houses. It is not one of the hibernating species, therefore as a rule it does not lay up stores; but Mr. Douglas English records the digging up of five Bank Voles with a store of ninety-three sound cob-nuts.
There are several litters of three to six naked and blind young during the year, produced in nests of grass, moss and wool, or feathers, usually placed above ground, sometimes in a bird's nest at some height above it. The males are very quarrelsome, and when fighting or pairing are very vocal, indulging in grunting squeaks.
Three geographical races or sub-species have been recognised by Barrett-Hamilton as distinct species under distinct names. These are Skomer Bank Vole (Evotomys skomerensis) from Skomer Island, off Pembroke; Alston's Bank Vole (E. alstoni) from the Isle of Mull; and the Raasay Bank Vole (E. erica) from Raasay Island, Skye. Barrett-Hamilton regards these as descendants of a former "Boreal" group of Voles, which have been supplanted on the British mainland by the competition of the Bank Vole.
[Pl. 72.]][H 112.
Retreat of the Bank Vole.
Run continues from hole (left) under exposed root (right).