The critically endangered water vole is showing signs of a comeback, according to a UK survey.
Water voles were once common on waterways across the country, but their numbers began to decline in the 1990s and, by 2005, 90% had disappeared.
The Environment Agency, which carried out the survey, said this makes it the UK's fastest declining mammal.
The agency added that its recovery had been stimulated by an improvement in river water quality.
It also cited success in the control of the water voles' main predator - mink.
The national survey identified 30 "vole hotspots", including grazing marshes and ditches in Yorkshire and Lancashire, moorlands in the Pennines and wetlands on the east coast of England.
But it also showed that the species is faring badly in many areas. "Water voles are extinct in Cornwall and the remaining two populations in Devon still very small," said the agency.
"The species continues to decline in many areas, including over much of the south east of England and in parts of south and west Wales."
In order to help the species recover in areas of decline, the agency's project workers are releasing hundreds of voles across England and Wales this year.