the largest British vole; often mistaken for a rat, they grow up to 20 centimetres long. They have dark fur and a long furry tail. They live in the banks of streams and ditches.

The Water Vole, Microtus richardsoni, is the largest North American vole. It is found in the northwestern United States and southern parts of western Canada. This animal has been historically considered a member of the genus Arvicola, but molecular evidence demonstrates that it is more closely related to North American Microtus (Conroy and Cook, 2000).