International Wildlife Encyclopedia - Vol. 21

International Wildlife Encyclopedia - Vol. 21

International Wildlife Encyclopedia - Vol. 21

International Wildlife Encyclopedia - Vol. 21

Excerpt

WATER VOLE

The water vole’s numbers are in decline in parts of Europe because of predation by mink and loss of suitable habitat. In Russia the species is also hunted by humans for its pelt.

THE WATER VOLE IS SOMETIMES Called the water rat. It is about the size of the common rat and can be easily mistaken for it in appearance. The head and body total 4¾-8½ inches (12–22 cm), and the tapering, hairy and ringed tail is 2¼-5 inches (6–13 cm) long. Its weight is in the range of 2½-4½ ounces (70–125 g) in winter to about 9 ounces (250 g) in summer. The female is slightly smaller than the male. The head is short and thick with a broad, rounded muzzle. The eyes are small and extremely shortsighted, and the small, round ears scarcely project beyond the surrounding fur. The limbs are relatively short. The nonwebbed feet have naked, pink soles with five rounded pads, but are covered with stiff hairs on the upper surface. All the toes bear claws. The thick, glossy fur varies from a blackish gray to a warm reddish brown above, sprinkled with gray, and the underparts are yellowish gray. A few melanistic (black) forms are found, as are albino strains.

The water vole, Anvicola terrestris, is found over most of Europe, parts of Russia and Siberia, Asia Minor, northern Syria, Israel and Iran. It is generally distributed throughout Britain, but its numbers are declining and it does not occur in Ireland or on the Scottish islands. The southwestern water vole, A. sapidus, lives entirely on land, burrowing rather like a mole. It is found only in France, Spain and Portugal.

Diving to safety

The water vole is found on the banks of streams, rivers and canals. It is thought to have a 4-hourly rhythm of activity throughout the day and night, with feeding periods of about half an hour alternating with periods of rest or random movement.

When a water vole suddenly plops into a stream or canal, its course can sometimes be tracked underwater. However, it often disappears immediately, to surface some distance away or retreat into a burrow in the bank, sometimes by an underwater entrance. It may regain the bank by an upper exit. It is a steady swimmer, its rate of progress being an even 2½-3 miles per hour (4–5 km/h), but it is less skillful in swimming than in diving.

Bedrooms and larders

The burrows made by water voles have long, winding passages with chambers for sleeping, lined with grass and hay, and chambers for storing food. The water vole digs them at great speed with the forefeet, throwing out the earth with the hind feet. It removes stones with the teeth and eats any roots that get in the way. The burrows sometimes cause damage to the banks of dikes and canals. However, the water vole also helps to keep waterways clear of weeds and rotting vegetation. The water vole does not hibernate, but it has been reported to lay up considerable stores for when food is scarce. Although it is aquatic, steady rain will keep it in its burrow or cause it to gather food from near the mouth of the burrow and eat it inside. Like the water shrew (discussed elsewhere), the water vole is sometimes found in fields far from water. It marks its home range with a scent from glands on the flanks conveyed to the ground by the hind feet.

Vegetable eater

The water vole’s diet features succulent grasses, flags, loosestrife, sedges and other plants that grow along river edges. The animal enjoys grains such as wheat, oats and millet, and apples are a special favorite. It is thought that it sometimes eats freshwater snails and mussels, as well as caddisworms and other insects, but this is not certain. Food stored in the burrow usually consists of different types of nuts, beech mast, acorns and the underground stems of horsetails.

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