There are three species of vole in Britain: the short-tailed or field vole, the bank vole and the water vole, which is the largest of the three and by far the rarest. Water voles (Arvicola amphibius) have experienced one of the most rapid and serious declines of any British wild mammal ever…
Habitat loss during the 20th Century and predation by the non-native American mink led to the disappearance of more than 90% of our water voles by the end of the 1990s. Mink, both fur-farm escapees and those released by well-meaning but misguided activists, were first reported as breeding in the wild in the UK in 1956; their presence has been devastating for our native river-side wildlife.
 Wild mink, an alien species in part responsible for falling water vole numbers;  water vole.
Research in the first decade of this century has recorded another 30% loss of water vole habitat in England and Wales. The situation is serious.
Water voles are uniformly dark brown and easily mistaken for brown rats but they are chunkier and rounder than rats with smaller ears and every bit of them is furry, including their tail. They are sometimes called water rats; Ratty from the Wind in the Willows was a water vole. They live in burrows in the banks of rivers, ditches, ponds, and streams. They like still or slow moving, water among lush and dense vegetation to provide them with cover.
Water voles are prolific breeders, raising up to five litters of an average six pups in a year. In sound and protected habitat, their populations can recover quickly but fragmentation of the wider habitat makes it difficult for the recovery to spread. Streams are interrupted by urban development, which also brings its own predators; industrial scale agriculture does not have time for lush and dense bank-side vegetation.
 the lush vegetation of Lambrok Stream;  water vole swimming
We have been aware of the park’s water voles for four years; they are shy and elusive so it is difficult to make any more than a guess at their population. The Lambrok, running slowly between clay banks, through reeds and bulrushes, willow herb and loosestrife is just the right place for them; let’s hope they stay.