Re-introduction of water voles at Malham Tarn

THE reintroduction of water voles to Malham Tarn in the Yorkshire Dales National Park is a good news story that has been discussed by many at college. All see it as a positive achievement but few are aware of the hard work and months of planning that preceded their release.

In 2008 I was lucky enough to be involved with the first dormouse (Muscardinus avellanarius) release scheme in Wensleydale, a second release took place this summer. In both, the actual release marked the culmination of years of hard work and this work continues today with volunteers monitoring nest boxes and managing habitats. For a release to work ecologists need to be sure that the original causes of decline, such as predators or habitat loss are no longer an issue. Then the animals need to be carefully sourced; their genetics should be as diverse as possible, you don’t want to start a population from closely related individuals but equally you want the animals to have genetics close to other UK populations. In this case the dormice were part of a captive breeding programme coordinated by the Peoples Trust for Endangered species. With the reintroduction of birds of prey the genetics can be an issue as remaining numbers might be so low that birds have to be sourced from abroad. The initial UK red kite releases used birds from Spain and Scandinavia although those released at Harewood House came from a reintroduction programme in the Chilterns.

Once selected animals are quarantined to check for diseases before being electronically tagged (for monitoring) and brought to the release site where staff and volunteers have already prepared release cages and nest boxes. In Wensleydale each nest box was carefully mapped so that their locations could be found in the future (unfortunately the GPS bounced off the trees so being able to read a map was essential). The dormice were then placed into the release cages, and checked for ten days before a small hole was cut into the cage to allow the dormice to escape. The release cages were then left in place for several months so that the dormice became accustomed to the wood and had a safe place to return to.

Dormice and water voles are cute and popular with the public and it is easy to gain funding and support for their release. Campaigns are often run using a “cute and cuddly” to front them whilst the habitat work on the ground aims to help a range of less charismatic creatures – there are few if any funds for the reintroduction of a rare midge or wasp! More controversial is the release of predators such as wolves and lynx and in a Moorland region birds of prey. The Red Kite released at Harewood are a familiar sight and this year 36 breeding pairs were recorded in West Yorkshire and 41 in North Yorkshire, however, despite their success there are cases of the birds being shot and I think it unlikely that this release will be followed by other birds of prey.

Plants are less controversial and although planting rare species is not seen as a release scheme, the genetics and habitat management requirements are just as important. The replanting of Lady’s slipper orchid Cypripedium calceolus is one local example. In the 1700’s the orchids were so common around Clapham that bunches were gathered for sale, now we are down to one remaining wild site in the National Park. It has taken years of research at Kew to develop the micro – propagation techniques needed to produce the viable seedlings that are now being replanted around the Dales. The original wild site is still carefully protected but the reintroduced plants can be viewed at a range of sites including Kilnsey Trout farm. This points to a further benefit that reintroduction can bring to a region, that of ecotourism. Many tourists visit sites in Scotland hoping to see released Beavers, and White tailed eagles and although some fear that we might be putting our wildlife into the “tree museums” foretold by Joni Mitchel in Big Yellow Taxi I hope that the success of ecotourism shows that the public value their surroundings and with luck the reintroduced species will spread out from their “museums” for all to enjoy.