Water voles 'decline by a fifth'
6 September 2013 Last updated at 03:16 BST
Water voles have declined by a fifth in the UK since 2011, a survey suggests.
Conservationists say that habitat loss, predation by American mink and changeable weather are to blame.
The research was carried out by the Environment Agency and Wildlife Trusts.
Alastair Driver, the National Conservation Manager from the Environment Agency, explains what has happened to this creature.