As spring burgeons, our back-garden field voles are busy with new life. They breed all year, but as April swells, reproduction reaches new peaks. Nests are appearing under the pond liner and the long grass at the foot of our apple tree. Carefully domed with grass stalks, these maternity nests are well camouflaged. They have to be – field voles are prey to just about every predator: barn owls, kestrels, weasels, stoats, foxes and snakes. Even the mighty buzzards, nesting in our neighbour’s ash tree, will eat them.