A project to help boost numbers of the water vole, one of the fastest-declining mammals in the UK, has been completed in mid Wales.
Water voles are finding it hard to maintain their population
Three new pools have been dug at a reserve in Ceredigion to encourage the local water vole population.
Once a familiar sight, numbers have fallen by 90% in the past century, according to a recent report.
The decline is being blamed on the loss of riverside habitats and predators such as the American mink.
Water voles tend to live in streams, ditches and ponds on agricultural land.
In Ceredigion, there is a thriving population at the Cors Ian reserve, near Lledrod, which is run by the Wildlife Trust of South and West Wales.
Lizzie Wilberforce of the trust has been assessing the strength of the reserve's population.
She has also been working with the Environment Agency's flood defence team and its biodiversity team on the pool digging project.
"The water voles were sticking to the western half of the reserve where there is a stream and the lack of a suitable habitat in the eastern half was keeping them away," said Dr Wilberforce.
"So with help of the Environment Agency and its five-tonne digger, we have dug three new pools for the water voles in the hope that they will disperse. This may provide an opportunity for the population to grow."
The water vole is finding it harder than ever to maintain its population. The State of Britain's Mammals Report 2005 said the rodent was "a contender for the UK's most rapidly-declining mammal".
Monitoring along 436km of watercourses in 2004 showed that in three-quarters of the areas surveyed, evidence for water vole presence had become scarcer.
But conservationists believe they can turn the species around by 2010.
Another significant factor in the downturn has been the introduction of the American mink, many of which escaped from fur farms.
The alien invader has driven out the water vole in many areas.
Other predators include stoats, owls, herons, large fish, foxes and domestic cats.