The European Water Vole (Arvicola amphibius formerly called A. terrestris) is a semi-aquatic mammal that resembles a rat. In fact, the water vole is often informally called the water rat.
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 2 years on average; most do not survive a second winter. In captivity, they normally start to deteriorate in condition as they approach their third year becoming thinner and losing much of their fur, nearly all die during their third winter.
AppearanceEditWater voles reach 140–220mm in length (5–9 inches) plus a tail of 55%–70% of this. Adults weigh from 160–350 g (6–12 ounces), juveniles weigh less but must reach around 140–170 g (5–6 ounces) to be able to survive their first winter.
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 live in reed beds where they will weave ball shaped nests above ground if no suitable banks exist in which to burrow.
Water voles prefer lush riparian vegetation which provides important cover to conceal animals when they are above ground adjacent to the water body. Areas of heavily grazed and trampled riparian habitats are generally avoided Water voles may be displaced by the introduction of riparian woodland and scrub as they prefer more open wetland habitats away from tree cover.
As well as frequenting typical lowland wetland habitats dominated by rank marginal aquatic vegetation, water voles are also just as at home in areas upland 'peatland' vegetation where they utilise suitable small ditches, rivers and lochs surrounded by moorland.
The mating period lasts from March into late autumn. The female vole's pregnancy lasts for approximately 21 days. Up to 8 baby voles can be born, each weighing around 10 g (one fifth 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 do not usually live in large groups. Adult water voles each have their own territories, which they mark with faecal latrines located either near the nest, burrow and favoured water's edge platforms where voles leave or enter the water. Latrines are known to be a good survey indicator of this species, and can be used to gauge abundance of animals They also scent-mark by using a secretion from their bodies (a flank gland), however this is not normally detectable during a field survey. They may attack if their territory is invaded by another Water Vole.