Keep mulch pulled away from the base of the tree, and examine it frequently for the presence of mice. In many home and commercial plantings, placing poison bait in their runways controls mice. These poisons and complete directions on how to use them may be obtained from many spray material dealers. Mice may also be controlled by trapping. This can be successful where only a few trees are involved.
Rabbits can also be responsible for the loss of young trees each year.
Where rabbits are a common problem, a satisfactory method of preventing damage is the use of a mechanical guard. Roll or bend the strip around the trunk of the tree so that the long side is up and down the trunk and the edges overlap. Twist a small wire loosely about the center to prevent the strip from unrolling. Push the lower edges well into the ground. This metal guard will last indefinitely and can be left in place all year.