Voles are short-tailed mice of the genus Microtus who have the very bad 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 are 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 push the snow down. This will create a barrier of hardened snow they won’t be able to penetrate. Note that, photo aside, it is permissible to wear winter boots to accomplish this task.