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The Water Vole (Arvicola terrestris) is a semi-aquatic mammal that resembles a rat. In fact, water voles have often been mistermed, "water rats". Water voles have rounder noses than rats, deep brown fur, chubby faces and short fuzzy ears; unlike the rat their tails, paws and ears are covered with hair.
In the wild, they survive for 5 months on average, most do not survive a second winter. In captivity, they survive for a maximum of 5 years.
Water voles reach 5-9 inches in length (120-235mm) plus a tail of 55%-70% of this. Adults weigh from 6-12 ounces (160-350g), juveniles weigh less but must reach around 5-6 ounces (150g) to be able to survive their first winter.
The water vole Arvicola terrestris, also known as the Northern water vole, is found in much of Great Britain, northern and central Europe and in parts of Russia. The Southern water vole, Arvicola sapidus, is found in most of France and south-westwards through Spain and Portugal. There is another water vole found in northwestern United States, and southwestern Canada. Some sources classify the water vole found in western North America as a separate species, either Microtus richardsoni or Arvicola richardsoni.
Water Voles have recently returned to Lindow Common in Cheshire, UK after many years of absence. Lindow Common
In Britain, water voles reside in burrows that they excavate from the banks of relatively calm rivers, ponds, and streams. In Europe and Russia, they may venture into woods, fields, and gardens. American and Canadian water voles dig burrows that are connected to water sources. They live under the snow during the winter.
Water voles mainly eat grass and plants near the water. At times, they will also consume fruits, bulbs, twigs, buds, and roots. In Europe, when there is enough food to last water voles a long time, water vole "plagues" can take place. Water voles eat ravenously, destroying entire fields of grass and leaving the fields full of burrows, during these plagues.
The mating period lasts from March into late Fall. The female vole's pregnancy lasts for approximately 21 days. Up to 8 baby voles can be born, each weighing close to two-tenths of an ounce. The young voles open their eyes three days after their birth. They are half the size of a full grown water vole by the time they are weaned.
Water Voles are expert swimmers and divers. They usually don't live in large groups. Adult water vole each have their own territories, which they mark with a secretion from their bodies. They will attack if their territory is invaded by another vole.
The water vole population in the UK has fallen from its estimated pre-1960 level of around 8 million to 2.3 million in 1990 and to 354,000 (other source: 750,000) in 1998. This represents a 90-95% loss. It is still declining dramatically, the most recent estimate for 2004 is around 220,000. This decline was mainly caused by the mink, an aggressive predator of the vole, together with unsympathetic farming and water course management which destroyed parts of the water vole's habitat.
Consequently, the water vole is the UK's fastest declining mammal and efforts are under way to protect the water vole and its habitat from further destruction.
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