Q: When I was outside the other day, I saw several tree branches missing big pieces of bark. They are in an area deer can’t reach. What could have caused this? Will the branches recover?

A: It is likely squirrels. They tend to remove large pieces of bark from thin-skinned trees in late winter, usually on horizontal branches. They might be doing this to get material to line their nests or just because they want it for food or they like the feeling of chewing.

Most stripping goes all the way around the branch, or nearly so. This kills that branch. Without the green layer just under the bark the branch will have no way to get nutrients from the tree and so it dies. It may leaf out normally in the spring, but only because it already formed the leaves back when it had bark. These branches are basically zombies.

Even if the damage goes only half way around the branch, you may want to prune back to an untouched area. With much of its support system missing, it will struggle and never really look right, so it is best to remove it before it dies and potentially causes problems in high winds. Pruning information can be found at: extension.umn.edu/planting-and-growing-guides/pruning-trees-and-shrubs.

Squirrel nests are quite large, and one squirrel may have more than one nest. They are either built in tree cavities or high up in trees, at least 20 feet up, and in a fork. They are formed of bark, small branches, leaves and moss. If you look around now before the trees leaf out, you may be surprised how many squirrel nests you see.

Written by U of M Extension Master Gardeners in St. Louis County. Send questions to features@duluthnews.com.