European water voles are semiaquatic rodents. They are often informally called water rats, though they only superficially resemble a true rat. Water voles have rounder noses than rats, deep brown fur, chubby faces and short fuzzy ears; unlike rats their tails, paws and ears are covered with hair. Overall, European water voles are a uniform dark brown colour, with slightly paler coloration on the underside. Their pelage is quite thick and they are furred over their entire body, including their tail, unlike rats. Their dark colour allows them to blend in well in the densely vegetated areas they inhabit.
European water voles are found in most of Europe, Russia, West Asia, and Kazakhstan. They live around rivers, streams, ponds, and other bodies of water. Water voles prefer lush riparian vegetation which provides important cover to conceal animals when they are above ground. In Europe and Russia, these animals may venture into woods, fields, and gardens. They live under the snow during the winter.
European water voles are expert swimmers and divers. They live in burrows excavated within the banks of rivers or streams. These burrows contain 1-2 nests and in the winter there are storage chambers for food. European water voles usually live in small families and are active during the day. Adults each have their own territories, which they mark with fecal latrines located either near the nest, burrow and favored water's edge platforms where voles leave or enter the water. They also scent-mark by using a secretion from their bodies (a flank gland). Individuals may attack if their territory is invaded by another water vole.
European water voles are herbivores. They mainly eat grass and other vegetation near the water, but will also consume fruits, bulbs, twigs, buds, and roots when given the opportunity. Water voles in some parts of England occasionally prey on frogs and tadpoles; it has been suggested that this is to make up for a protein deficiency in the voles' diet.
Little is known about them mating system in European water voles. However, it is known that most vole species are polygynous. The breeding season lasts from March into late autumn. The gestation period lasts for approximately 21 days. Females give birth up to 8 baby voles, each weighing around 10 grams (0.4 oz). 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. Weaning occurs in 14-21 days after birth.
Main threats to European water voles are habitat loss, water pollution, predation by introduced American mink and competition by the introduced muskrat. In some areas water voles are also considered an agricultural pest.
According to IUCN, the European water vole is abundant and widespread throughout its range but no overall population estimate is available. However, according to Wikipedia resource, the most recent estimate of its populations in the UK for 2004 is around 220,000 individuals. Currently, European water voles are classified as Least Concern (LC) on the IUCN Red List and their numbers today are stable.