"Believe me, my young friend, there is nothing - absolutely nothing - half so much worth doing as simply messing about in boats”
Rat, Chapter 1 ...
Kenneth Grahame, The Wind in the Willows
The European water vole, Arvicola amphibius, Linnaeus (1758), formerly A. terrestris, is widespread across Europe where it lives in the well-vegetated banks of slow moving streams, rivers, dykes and other waterways. It is found throughout Britain where it is generally confined to low ground. It is absent from Ireland. The extensive waterside burrows of these strong swimmers have many levels that help to prevent flooding, as well as chambers for nesting and food storage. Burrow systems are typically located in the steepest parts of the bank and usually have underwater entrances to give the animals a secure escape route if danger threatens.
A. amphibius has a diet of grasses and waterside vegetation, though other broadleaved plants are also eaten. Where blades are bitten off the imprint of the two large incisors is both prominent and diagnostic. It is not uncommon to see "lawns" of closely manicured grass, occasionally with piles of chopped food, around burrow entrances. A. amphibius tend to be more active during the day than at night. The males range along about 130 metres of water bank, while females restrict their range to about 70 metres. Ranges of both sexes and all age classes are reduced during the winter period. They deposit their distinctive black, shiny faeces in latrines, which occur throughout and at the edges of their range and wherever they leave or enter the water. Three or four litters a year are typical. In mild springs the first of these can be born as early as March or April; though adverse conditions will delay breeding until May or even June. There are about five young in an average litter, which are born below ground in a nest lined with finely shredded grasses and reeds. Although blind and hairless at birth, the young develop quickly and are weaned at 14 days. On average, water voles only live about five months in the wild.
Their most important predators are mink and stoats; though other predators are known to take them. They have sadly experienced one of the most severe declines of any wild mammal in Britain during the 20th century. Changes in farming practices during the 1940s and 1950s caused the loss and degradation of suitable habitats but the most rapid period of decline was undoubtedly during the 1980s and 1990s when the American mink (Neovison vison) spread rapidly across the country having been released from fur farms. Between 1990 and 1998, the population dropped by a staggering 90%.
Arvicola amphibius is an excellent flagship species and one which we should endevour to protect. Their presence reflects a healthy aquatic environment and associated waterside communities.