'Ratty' under threat as water vole numbers 'down by a fifth'
Water voles may have declined by as much as a fifth in just a few years, a new study mapping their presence across the UK has suggested.
The mammal immortalised as Ratty in Wind In The Willows is still thriving in strongholds from the uplands of Snowdonia to the wetland habitats of the eastern England fens and the Somerset Levels.
But elsewhere, populations are disappearing in the face of habitat loss, being eaten by invasive American mink and suffering weather extremes, the Environment Agency and Wildlife Trusts said.
Water voles were once widespread, but saw numbers crash by 90% in the 1990s as a result of predation by mink – which have established themselves in the countryside after escaping from fur farms – and loss of riverbank habitat.
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Data published in 2010 indicated populations in some parts of the country were making a comeback, but new information from the national water vole database and mapping project paints a more gloomy picture.
The mapping shows the number and extent of key areas for water voles had shrunk, and across large parts of the country, populations appear to be small, isolated and vulnerable, conservationists said.
In such areas, water vole populations are at risk from the arrival of American mink and the impacts of drought, when falling water levels expose underwater burrow entrances to other predators, or flooding.
The latest data, which collates and maps figures from surveys conducted around the UK, suggests the presence of water voles is down by 22% for the period 2007-2011 compared to 2004-2008.
Between 2004 and 2008 they were recorded in 874 10km squares, but for the period 2007-2011 they were present in 683 such areas.
Some of the fall is down to a reduction in surveying in recent years as the recession has reduced conservation funding, and experts said it was hard to assess what was happening to the UK-wide water vole population as there had not been a national survey since 1998.
But Paul Wilkinson of the Wildlife Trusts said the latest data was a real cause for concern, and warned: “Not enough is being done to secure this charismatic species’ future.”
There was clear evidence from some areas such as the south of England that water voles were disappearing fast, he said.
“Strongholds do remain, and these are often located in areas which support more extensive wetland habitats, such as the fens, or head streams in upland areas.
“We must ensure these strongholds persist and renew efforts to save this much-loved species, through targeted conservation action and sustained monitoring programmes,” he urged.
Conservationists called for more resources to support water vole surveying and conservation projects, saying a clear benefit could be seen from efforts to create and protect suitable habitat and control mink numbers.
Alastair Driver, Environment Agency national conservation manager and chairman of the UK water vole steering group, which produced the analysis, said: “Creating new habitat helps protect our native species, like water voles and otters, and helps tackle climate change.
“The Environment Agency has created nearly 5,000 hectares (12,400 acres) of wetland and river habitats in the last 10 years and we hope to double this in the next 10.
“Added to this, our rivers are at their healthiest for over 20 years, but control of the American mink is essential if water voles are to benefit from these healthier rivers and new habitats.”
Successful reintroductions of water voles, along with controlling mink, have also resulted in new populations in places such as the River Axe in Devon and London Wetland Centre, the experts said.