THE water vole, famed since the novel The Wind In The Willows, is among the country's rarest animals, having come close to being wiped out 15 years ago.

But a leading wildlife charity has discovered plenty of evidence the vole is fighting back and thriving in areas of Scotland.

The experts have identified colonies of the elusive semi-aquatic rodents, epitomised for generations of children by the character Ratty (though actually a water vole) in Kenneth Grahame's enchanting tale, in Glasgow, Stirling and the Highlands.

James Silvey, nature recovery officer with RSPB Scotland, who has carried out a major study on the creatures, said he hoped their numbers would continue to grow.

He said: "It is extremely difficult to estimate numbers as their population can vary from season to season. However, this year we have had numerous reports of water voles returning to areas where they haven't been seen for over 30 years, so in some areas water voles seem to be doing very well."

Mr Silvey said now is the best time of year to see water voles at first hand as their numbers are at their highest following the end of the breeding season.

He added the creatures were particularly thriving in Cardowan Moss Woodland in Glasgow, and the Loch Ard forest near Aberfoyle in the Loch Lomond and Trossachs National Park, where a project to reintroduce the animals began in 2008.

A report this month by Scottish Natural Heritage found eight colonies at the Beinn Eighe National Nature Reserve in Torridon, while in July RSPB Scotland recorded two colonies in a part of the Highlands for the first time in 20 years. The population was spotted at the charity's Insh Marshes reserve in Strathspey, near Kingussie.

Eoghain Maclean, manager at Beinn Eighe national nature reserve, said: "It is very seldom you see water voles, but there ­definitely seems to have been an upturn in their number. In our study we saw them living at 900 feet which was especially exciting."

Water voles live along the grassy edges of burns, rivers and ditches, creating extensive systems of burrows, tunnels and nesting chambers which provide refuge from predators and floods. They were once common throughout Britain but their population has plummeted by 94 per cent since the 1950s. By 2000 they were close to being extinct in many areas.

It is believed the main causes was the drainage and destruction of wetlands, changes in land management with the removal of field-edge ditches and dykes as well as the establishment in the wild of the invasive American mink.

Mink were introduced into Scotland in the 1920s for fur ­farming, but following escapes and releases they began living in the wild in the 1950s, when they began to kill and eat the smaller water voles.

Scientists believe water vole numbers have soared after moves to conserve their habitats and following the introduction in 2011 of the Scottish Mink Initiative, a charitable conservative programme to reduce the voles' main predator. However, despite the upturn in voles' numbers in some parts of Scotland, the mammals are still rare.

Mr Silvey added: "While there are these hot spots where water voles seem to be doing well, the bigger picture across the UK is that we have seen a 90 per cent decline. It is still Britain's fastest declining mammal."

Yet, water voles have legal protection. This provides for their shelters, making it an offence to intentionally damage their homes and disturb the creatures.

The Scottish species is genetically distinct from its English and Welsh cousin and usually has black, rather than brown, fur.