Water Vole

Water voles’ tunnels help to erode the islands.

In many places the ground can be completely undermined by water vole tunnels and this can be a significant contributory factor in the erosion of the lowest lying islands. The water vole is herbivorous and does not therefore trouble the breeding birds, as the rat does. Any predators that come to the islands can have a devastating effect on water voles. Foxes, stoats, minks, martens and rats can make major inroads in the population. This can sometimes lead to the complete eradication of water voles on the island concerned.


Seed bed formed by soil dug up by water voles.

Water voles have a significant effect on plant life on the islands, partly because they eat the plants, but just as much because the earth thrown up from their tunnels provides a seed bed for annual and biennial plants.


Greater musk-mallow grows in soil cast up by water voles.

When a stoat eradicated water voles on Langholm in Lejre Vig in 1985 there was an abrupt decline in greater musk-mallow and other annuals and biennials, which were outcompeted by grasses etc. The same stoat also had a huge impact on the breeding birds. A good example of how little it takes to disturb the balance of nature in these small isolated biotopes. Water voles are excellent swimmers and it is therefore rarely long before they return to places where they have been eradicated.