Water vole

An underground grafter

Water vole. Eero Haapanen.

The water vole is the largest Arvicolinae species in Finland; water voles may be as long as the hand span. They are excellent swimmers, and they make visible paths and holes in ditch banks. They live on the outer islets of Helsinki and sometimes even in very dry spots. They cause trouble in gardens, as they may pilfer potatoes or gnaw at apple tree roots.

Owls consider water voles to be excellent nutrition, and the northern goshawk may be on the lookout for them while sitting on fenceposts in Viikki.