Water voles were once widespread across the UK, inhabiting streams, rivers, canals, and wetlands.
However, their numbers have declined dramatically since the 1970s due to habitat loss and predation by the American mink.
Mink were brought to the UK in the last century for fur farming, but those that escaped and others that were deliberately released by animal rights activists established themselves in the wild.
Now there are projects underway to bring water voles back and control the mink.
Paul Whitfield, chief executive of Wildwood Trust, said: “Water vole captive breeding and reintroduction projects are incredibly important for the species.
“This is a species that has declined by 90%. We’re really losing these animals. They’re endangered.”
He added: “They don’t travel very far so it’s really essential that when we find good habitat we are able to put the water voles back to establish a population.”