Four to six foot tall white spruce growing in the yard of rural residents near Roseau in Roseau County were damaged by voles gnawing off bark from the underside of branches both near the ground and in other parts of the crown. Trees that were near the woods edge and elsewhere where some kind of ground cover exists were especially hard hit. Voles and mice will chew the bark off trees or whatever that looks edible to them during the winter when other food is not available to them.
The best way to prevent voles and mice from chewing up your trees is to eliminate ground cover or nesting materials around the base of trees. Placing cinders around the base of trees or encircling the base with hardware cloth (screen) may also be helpful. The best long term and natural control of voles and mice damage is through predatory species such as weasels, skunks, hawks, owls and snakes.