All you need to do to create a vole barrier is to pack snow down around susceptible trees and shrubs. Ill.: http://www.slideshare.net & webstockreview.net, montage: laidbackgardener.blog
Voles are short-tailed, small-eared mice that are rarely seen, but that have the annoying habit of gnawing the bark of shrubs and young trees during the winter.
They especially like fruit tree bark and will often kill young trees by ringing them entirely (removing a full circle of bark). It’s in years when snow is abundant that they’re the most harmful, as they dig tunnels under the snow to their favorite plants and can do their damage out of sight of their usual predators (owls, foxes, cats, etc.).
One easy way to discourage voles is to walk all around susceptible plants to pack the snow down. This will create a barrier of hardened snow they won’t be able to penetrate.
All you need to carry this treatment out is a good pair of winter boots!