MALHAM Tarn is set to become even more popular after around a hundred water voles - the inspiration for Ratty in Kenneth Grahames' Wind in the Willows - were re-introduced back into its waters.

The re-introduction of the charismatic wild mammal - which are a tasty snack for other struggling predators, the barn owl and otters, even made it onto Radio Four's Today programme, with presenter John Humphrys welcoming back Ratty to the Yorkshire Dales.

Water voles, the country's fastest declining wild mammal, have not been seen at Malham Tarn for 50 years - believed to have been wiped out by mink, which escaped from nearby fur farms.

Once a common sight, their numbers have dropped by almost 90 per cent in recent years.

Now, the re-introduction back into England's highest freshwater lake is believed to be the highest number brought back into an area carried out in the country.

The National Trust is reintroducing the water voles, which have been bred in captivity, as part of its major new vision for land management in the Yorkshire Dales.

The conservation charity is taking a nature-first approach to managing the 8,000 hectares of moorland, farmland and woods that it cares for in the Yorkshire national park.

And the water voles will play an important part in the ecosystem at Malham Tarn, grazing and burrowing into areas of the riverbank and providing the space for rare plants like scarce mosses and liverworts that need patches of open habitat to grow.

The voles are also set to become food, as they act as a food source for struggling predators including barn owls and otters.

Roisin Black, National Trust Ranger at Malham Tarn, said: “In the rest of Europe, water voles are common. In Britain, the creatures are incredibly rare. We know water voles have thrived at Malham Tarn in the past and thanks to work by the National Trust, the habitat here is perfect for water voles again.

“By reintroducing water voles to the tarn, we hope to give these rare animals the chance to re colonise the streams in the high Yorkshire Dales.”

It is planned that a further hundred voles will be release in the fen area of the tarn in June next year.

This year's animals have been specially bred for the charity by the Derek Gow Consultancy, an ecological consultancy with 18 years’ experience working on wildlife reintroduction projects.

Their release took place over five days, with the animals spending two days in large cages, placed on the edge of the tarn.

On the third day, the cage doors were opened and the voles were tempted out by food placed on rafts in the water and encouraged to bujild their own burrows.

The cages were removed on the fifth day.

National Trust rangers will monitor the health of the water vole population over the coming years, and it is hoped the animals will once again become a common sight at the tarn and its surrounding streams.

Peter Welsh, ecologist for the National Trust in the Yorkshire Dales, said: “Water voles once played an important part in the ecosystem at Malham Tarn. Reintroducing them to the tarn is just one of the ways we are working alongside our farmers and other partners to restore wildlife and natural processes in the Yorkshire Dales landscapes we care for.”

Water vole (Arvicola amphibius) facts

Water voles are about 12 inches long, including the tail, and weigh about the same as a half size tin of baked beans.

They live in burrows, dug into banks of slow moving rivers, streams, ditches and in wetlands.

They are mainly herbivores, eating grass and other waterside vegetation, and will eat around 80 per cent of its body weight every day.

Water voles love sweet treats. During the release at Malham Tarn the water voles were fed apples and carrots, and will together be fed 50 apples a day by the rangers as treats.

Depending on their age and sex, they have a territory of between 30 and 300 metres.

Water voles will produce between two and five litters every year, with each litter comprising up to eight pups

Young voles are weaned at two weeks of age. They live for up to three years in captivity, while in the wild they can make an easy meal for predators and have a life expectancy of just five months

Threats to water voles include being eaten by mink, industrialisation of agriculture, housing development on floodplains and pollution of waterways