Some people think squirrels are pests, while others find them fun to watch. No matter what you think about squirrels, you’re probably here to find out if squirrels are hurting your trees…
Squirrels harm trees when they strip too much bark off a tree. This exposes the tree to diseases and insects, which can kill parts of the tree or even the entire tree. When squirrels strip off a little bark, bite off twigs, or live in holes in tree trunks, they don’t do any serious harm or permanent damage to the tree.
There are two kinds of squirrels in this world: ground squirrels and tree squirrels. The first kind lives on the ground and the other lives in trees, but both can reach the trees in your backyard. Let’s take a look at three things squirrels do to trees and how much harm they really cause.
Squirrels strip tree bark
Source: Todd Watson, Texas A&M University, Bugwood.org
The hard bark around a tree’s trunk and branches protects the tree from the weather, pests and disease. Tree bark also covers an important layer inside, called the phloem, where food and water are carried around the tree.
Squirrels like to strip the bark off trees. They pull the bark off with their teeth and chew on it or take it back to their nest. Tree squirrels strip bark from a tree’s branches or higher up the tree trunk, and ground squirrels take bark from lower on the tree trunk, close to the soil.
Squirrels often enjoy eating the sweet sap that runs under the bark, which carries sugars and nutrients around the tree.
Sometimes squirrels pull off small pieces of bark, sometimes they strip a large patch off a single branch, and other times they girdle the tree. Girdling is when a squirrel strips the bark in a full circle around the trunk.
A tree can survive some bark stripping, especially if it’s only here and there on a few branches. But if squirrels strip too much bark from the tree trunk or if a squirrel girdles the tree, the tree loses its important protective layer and is more likely to get diseased or damaged. Over time, everything above the girdle line usually dies.
If a branch is girdled then the branch may fall off. If the main trunk is gridled, the tree may die and eventually fall over.
Source: Terry S. Price, Georgia Forestry Commission, Bugwood.org
How to tell if a squirrel is stripping the bark on a tree
You can usually tell that an animal is stripping bark from a tree if you see patches of bark disappearing from the tree’s trunk or branches. There may also be girdling, with a ring of bark missing from around the tree trunk.
If there is a branch or tree trunk that has been girdled, you may want to chop off the branch or cut down the tree below the girdle before it dies and the branch or tree falls onto something valuable in your yard.
The only way to be sure that squirrels are stripping the bark is to see them do it. There are many animals that like to strip bark from trees, such as porcupines, rabbits, beavers, and rats. Click here to find out how to tell the difference between a squirrel and a rat.
If you want more information about girdling, this video has a lot of information about the long-term damage squirrels cause through bark stripping:
Squirrels nip off branches
Squirrels bite off young branches or twigs in trees, probably to keep their front teeth short. Squirrels are rodents, like mice, so their front teeth never stop growing. Gnawing on things like twigs helps to grind down a squirrel’s teeth, so the teeth don’t grow too long for the animal’s mouth. If their teeth get too long, they can’t eat and they starve to death.
Even though squirrels break off many twigs on trees, this doesn’t usually harm the tree. In fact, it’s nature’s way of pruning the tree and can even make your tree bushier over time.
Trees are hardy and can survive some damage to their leaves, buds, and twigs. It would take an army of squirrels eating the twigs on one tree for a long time before any permanent damage occurred.
How to tell if a squirrel is biting off twigs
When squirrels chew on twigs, they break off the twigs or small branches from the tree and drop them to the ground. They don’t chew on the leaves or the stem. The twigs are usually small healthy new twigs with leaves on them, scattered on the ground under the tree.
Pick up a few and inspect them: They will have a slanted or clean cut on the end, where the squirrel’s teeth chopped them off.
Source: USDA Forest Service – North Central Research Station , USDA Forest Service, Bugwood.org
Squirrels can make tree holes bigger
Although squirrels sometimes strip bark, they cannot chew holes in trees to build their nests.
Quite simply, squirrels don’t make holes in trees.
So, what does make holes in trees?
According to the University of Connecticut, the following birds and insects make holes in tree trunks and branches:
- Wood-boring insects, such as bark beetles, emerald ash borers, and longhorn beetles
- Woodpecker birds
- Sapsucker birds
But not all tree holes are made by these insects and birds. Sometimes a tree gets a disease called heart rot. This disease is caused by a fungi that eats the tree from the inside out, making the inside of the tree soft and crumbly, with a hole in in it.
Squirrels like to find holes made by birds, insects, or fungi. The squirrels then make a nest in the hole or store food in there. They often choose to sleep in these tree cavities during cold winters to stay warm.
Source: Randy Cyr, Greentree, Bugwood.org
If squirrels spend a lot of time in their hole, they might strip bark near the hole or gnaw on the trunk inside and around the hole to grind down their teeth. Sometimes this makes the hole larger than what it was, but not always.
A squirrel living in a hole isn’t harmful and does no real damage to the tree, unless the squirrel strips too much bark near this hole or gnaws too much inside the hole.
A squirrel hole won’t kill a tree. But the cause of the hole, such as heart rot, insect infestations, or other diseases may kill the tree.
How to tell if a squirrel is using a hole in your tree
If there is a hole in one of your trees, the only way you can be sure there’s a squirrel in there is by seeing it coming and going.
You can also look for stripped bark near the hole as a sign that you have squirrels.
A hole in your tree is not made by squirrels. If you see a hole and you’re concerned, take a closer look to see if your tree has heart rot or is infested with wood boring beetles. If not, then there may be woodpeckers or sapsuckers flying in to eat treats from your tree when you aren’t looking.
Preventing squirrel damage to trees
You’ll never get rid of all the squirrels in your backyard. Even if you could, new ones would move into the vacated trees anyway.
Here are some things you can try to prevent squirrel damage in your yard:
- Use non-toxic repellent sprays, like this mace spray from Amazon, to keep them out of your yard or away from certain trees.
- Sprinkle cinnamon or capsaicin on the parts of your trees where squirrels hang out, but be careful as these can be harmful to birds and some plants.
- Protect seedlings and other small trees with PVC, aluminum, or some type of cloche.
- If you don’t mind the sight of galvanized aluminum in our yard, wrap your trees in aluminum as seen in this YouTube video:
Final thoughts
Squirrels debark trees and nip off twigs as they grow. Trees are most vulnerable when they’re young, so if you have lots of squirrels on your property, you should take steps to protect your growing saplings.
