Vole trapping fences - a new approach to migration barriers

To control problematic vole species in organic orchards farmers can choose between different measures. Some methods like gassing, trapping and even the support of natural vole antagonists target to reduce vole population by killing individuals. Other methods like protective guards or migration barriers exclude voles from single trees or whole orchards. Recent combinations of the two approaches worked well but had some drawbacks in practice. Nevertheless, efficiency of migration barriers can be improved by attracted natural predators. Here we present first practical experiences and field observations of a vole-trapping-fence prototype. The new construction consists of prefabricated recyclable polypropylene pieces which are mounted to modules and assembled to fences of any length. It has a H-shaped profile with the horizontal line at ground level. The two „legs“ are pushed into the ground and the two „arms“ building a double wall fence above ground. Through one-way doors voles can enter the space between the walls they are trapped in. In contrast to wire mesh fences it allows the seasonal use in annual cultures due to its fast mounting and dismantling features. For the long term protection of orchards, however, an additional wire mesh to prevent deep tunnelling is still recommended. The above ground construction has shown some additional advantages as maintenance is easier with a decreased risk of penetration by mowing devices. Most important the new construction improved the accessibility by predators as not only terrestrial but also avian predators were attracted and were able to take the captured voles.