Northern water vole, Water rat
European water voles > (Arvicola amphibius) are semiaquatic rodents. They are often informally called water rats, though they only superficially resemble a true rat. Their dark color allows them to blend in well in the densely vegetated areas and stay unnoticed.
European water voles are a uniform dark brown, 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.
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. In Britain, Water voles live in burrows excavated within the banks of rivers, ditches, ponds, and streams. Their burrows are usually located adjacent to slow moving, calm water which they seem to prefer. They also live in reed beds where they will weave ball-shaped nests above ground if no suitable banks exist in which to burrow.
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 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 (graminivores, folivores). 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 the 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 to 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.
The main threats to European water voles are habitat loss, water pollution, predation by the 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.