Rare water voles are flourishing against the odds in England’s highest freshwater lake following a reintroduction programme by the National Trust last summer.
More than a hundred water voles, which were the inspiration for Wind in the Willows’ Ratty, were released onto streams around Malham Tarn in the Yorkshire Dales in August last year. It was the first time water voles had been seen on the lake in 50 years.
And, in an adventure worthy of Ratty, Mole and Toad from the Kenneth Grahame classic, the water voles are spreading across the lake – in ways that National Trust rangers could never have dreamed.
Survey work has shown that the water voles – which are the UK’s fastest declining land mammal – have spread up to a kilometre from the original release site. Almost a year on from the original release, rangers will be reintroducing 100 new water voles to Malham Tarn.
Roisin Black, National Trust ranger at Malham Tarn, said: “With a mild, wet winter, we were worried that the water levels around the tarn may rise too high and flood the burrows. But it turns out that the voles have spread out across one side of the tarn.”
One vole has even been caught on camera in a favourite haunt for one of the tarn’s otters – one of the predators that will occasionally target water voles.
“An opportunistic otter might go for a water vole, but generally the can live very happily side by side,” Roisin said. “The presence of the otter helps deter the mink – which are behind water voles’ shocking declines.”
A hundred new water voles will be released onto the fenland surrounding Malham Tarn over the course of this week (starting 29 May). The water voles, which have been specially bred by expert ecologists at Derek Gow Consultancy, will be released in sibling groups and breeding pairs.
The release will be staggered over seven days due to the different needs of the groups and pairs. The animals will spend three or four days in large cages, placed on the fringe of the tarn. On the fourth and fifth day the cage doors will be opened. Food placed just outside the cage entrances will encourage the voles to leave the cages and build burrows. After the seventh day the cages will be removed.
The reintroduction is part of a plan by the National Trust to restore wildlife in the Yorkshire Dales. The charity cares for 8,000 hectares of woodland, meadows and moor in the Dales – England’s second largest National Park.
The water voles are helping to restore Malham Tarn’s sensitive lowland fen fringe – one of fifty ‘priority’ habitats handpicked by government as in need of support. The National Trust aims to create 25,000 hectares of new ‘priority’ nature habitats by 2025.
Ranger Roisin Black added: “The water voles area already changing the look of the tarn-side streams. The banks used to be straight-sided, almost like canals.
“But by burrowing into the banks, the voles have created much more natural-looking streams with shady pools that should be really good for invertebrates and small fish.”
National Trust rangers will spend the coming months surveying water voles, looking for signs like the animals’ ‘litter’ (excrement), burrows and nibbled grass ends.
“It will let us estimate the number of water voles we have here at Malham Tarn,” Roisin added.
How do you reintroduce a water vole? Six questions with Malham Tarn ranger Roisin Black.