The European water vole or northern water vole (Arvicola amphibius), is a semi-aquatic rodent. It is often informally called the water rat, though it only superficially resembles 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. In the wild, on average, water voles only live about five months. Maximum longevity in captivity is two and a half years. Appearance Water voles reach in length, plus a tail which is about half the length of the body. Weights reported for adults are variable. It is possible for large, optimal adults to weigh as much as However, these are peak weights. Elsewhere, the mean body mass has been reported as , although this figure includes immature water voles. The minimum weight to successfully breed as well as to survive winter is reportedly in females and in males. As a species the mean body mass is claimed as . 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. Taxonomy The binomial applied to the European water vole is Arvicola amphibius; it was formerly known by the junior synonym A. terrestris. The confusion stems from the fact that Linnaeus described two species of water vole on the same page of the same work. Those two forms are now universally considered the same species. It has been recognized as A. amphibius (Linnaeus, 1758) because the first source to unite the two forms, which Linnaeus had treated separately, into a single species chose A. amphibius as the valid name. The species is widely known by the synonym A. terrestris, which for many decades was treated as the valid name. Some authorities consider the southwestern water vole (Arvicola sapidus) to be the same species, but it is now generally considered distinct. Range The European water vole (Arvicola amphibius) is found in most of Europe, Russia, West Asia and Kazakhstan. Habitat In Britain, water voles live in burrows excavated within the banks of rivers, ditches, ponds, and streams. Burrows are normally located adjacent to slow moving, calm water which they seem to prefer. They also