For tree owners, noticing things out of the ordinary hopefully comes once in a blue moon. If you’ve noticed a weird-looking hole in your tree, you may feel that there is some cause for concern, but how much concern?
Many trees develop holes (also known as hollows) due to animals, natural events like storms, or human interference. These holes on your tree will likely not significantly hinder it, but they will change the appearance and maybe even attract more critters that prefer to live in tree hollows.
Often, you may not even notice smaller holes caused by insects or man-made borers, but take note of larger holes caused by animals and after storm damage. Stick around for a while to learn about the causes of holes in your tree, as well as the likelihood that it will survive!
Why Are There Holes In Your Tree?
As we talk about the holes that can be found in trees, it is important to mention that these holes can be caused by three primary culprits: weather, animals, and humans.
Not so surprising, right?
Holes have been made in trees for as long as trees have been around. While the man-made component of holes in trees has evolved over time from tapping sap to tree testing, most of the natural formations of tree holes and hollows have remained the same over time.
If your tree has some small holes, likely the cause is a group of insects or testing that was done on your tree. Larger holes, however, are thanks to the weather and larger critters like birds.
So, are holes a problem to a tree and, if so, what types?
Are Holes An Issue For Trees?
There are many outcomes of having a hole in your tree, and the size of the hole tends to be a big factor.
Smaller holes will have a lesser impact on the well-being of trees, especially those that are healthy and stable, to begin with.
If you are working with a tree that has already been damaged in some way, be it an infestation, weather, decay, or malnourishment, even small holes may begin to cause problems.
When it comes to larger holes, you’ve no doubt seen tree hollows before. They are those large holes in trees that look like the tree is almost fallen in on itself.
Tree hollows are a great example of the way that holes do not necessarily mean that a tree is damaged permanently. These can be caused by holes that then were able to heal and recover, growing new tree bark around all edges of the wound to incorporate this hole as a new part of a healthy, living tree.
According to the University of Florida, cavities and hollows do not mean that a tree is going to fall down, but there is a chance of that happening if the amount of wood near the trunk is not enough to hold up the rest of the tree.
So often, deadwood will decay while living wood can remain and give the tree a fighting chance at continuing on with a cavity.
The success of trees so often comes back to structural integrity above all else, since they can frequently overcome damages like local decay, insect infestations, and lack of water.
All of these things can be managed on their own, but structural integrity puts a tree into a whole different category of concern.
7 Reasons Your Tree Has Holes
There are multiple reasons your tree might have holes, including interference from humans and animals.
In these cases, there might be less cause for overall concern.
The holes that may pose a larger threat are holes that are, well… larger themselves. These types of holes are going to most commonly be the result of a big storm or some other natural disaster.
If the bark is already weak or damaged, there is a higher chance that any of the following causes of holes may lead to a more intense issue.
Strong trees can withstand a greater deal of damage, including holes before the effects begin to show up.
1. Holes From Tree Testing
Increment boring is one of the least damaging ways that a tree can get a hole. This is actually designed to cause the least amount of harm to a tree.
This specialized tool works to take out a small sample of tissue from a living tree so that it can be tested.
Most commonly, an increment borer is used by researchers, foresters, and other scientists to determine a tree’s age.
However, an increment borer can be purchased if you are ever curious to learn the age of your tree. Products like the JIM-GEM 12” 3 Thread .200 Increment Borer can be obtained by anyone willing to learn to use one.
If you are not someone that has a background in science, namely forestry or dendrology, please do not try to bore a hole in your tree by yourself. While this can be a great way to learn more about your tree and its age, boring a hole when untrained could be potentially dangerous to your tree.
Wait, didn’t we just say that this is one of the least problematic ways that a tree can end up with a hole?
It is, but only when bored by a trained professional who knows how to use the tool. Keep that in mind with most things regarding your tree, something that can be done with minimal harm by a trained professional could be quite detrimental when done by someone with no experience.
That’s why you should always reach out to a professional in your area if you have concerns!
Speaking of things that we do as individual tree owners, let’s discuss tapping your tree.
2. Holes From Tapping For Sap
Tapping a tree is something that tree owners can do relatively easily, and you can learn more about how to tap trees for maple syrup before you get started.
When tapping a tree, the hole should be at least 2 to 4 feet off the ground so that the base of the tree is not over-exerted. Your spile should be placed at a bit of an upward angle to ensure that sap properly drains.
To allow the sap to easily reach your bucket, the spile should go a few inches into the tree. This way, the sap will easily flow and while you’ll certainly have a hole in your tree it will not go in far enough to cause undue damage to the tree itself.
When tapping a tree, similar to increment boring, the hole should not be big enough to cause any damage to the tree. The issue is more about how far in the spile goes or if the tree is bored or tapped incorrectly.
Again, when in doubt, look around- do some extra research, talk to someone at your local nursery, or call a professional to help you.
3. Holes From Woodpeckers
Woodpeckers are a bird that you are likely familiar with, and one that you may have expected to see in this article.
Woodpeckers can hear insects under the bark and through the wood of a tree thanks to their impeccable hearing. They use their long beaks to tap through the wood and get access to insects that are below the surface.
While these birds can peck through solid, healthy wood and bark, they also tend to seek out sections that have a bit of decay already making it easier to peck through weakened wood.
Older trees, dying, or that have any sort of significant damage are always first on woodpeckers’ list of places to easily obtain their food.
Not only do woodpeckers peck myriad little holes into trees, but they also utilize larger holes and create nests where they can live.
4. Holes From Other Birds
Woodpeckers are not the only kind of bird that creates holes in trees. Chickadees and nuthatches are songbirds that like to rest and make their nests in cavities and hollows of trees.
Though they do not peck in the same way that woodpeckers do, they utilize tree decay in a very similar way.
Since these two types of birds also have pointed, thin beaks, they may peck away at the decayed area that they choose to nest in. They may also find other weakened areas of a tree and opt to get their meal of insects in a way quite similar to their counterpart, the woodpecker.
5. Holes From Boring Insects
Aside from the birds that peck away through trees to get insects, those same insects also have to get below the bark and into the wood of the tree.
So, insects that are borers like beetles, wasps, moths, and some other species will be another culprit for causing these tiny holes in trees.
Though their direct impact may be the smallest of these all, they begin a chain reaction that can cause a tree the most harm in the end, which is why we recommend using a product like this BioAdvanced 701900B 12-Month Tree and Shrub Protect and Feed Insect Killer and Fertilizer, to ensure that bugs don’t cause harm to your tree.
Picture this, you don’t spray for insects and they bore into your tree. Next, a woodpecker, nuthatch, or chickadee comes along and creates a bigger hole, then there is a storm and there are already some weakened areas that are more susceptible to damage.
This can lead to an array of very serious issues.
On the note of storms, though, let’s talk about storm damage and its consequences.
6. Holes From Storm Damage
A limb or branch that is broken off in a storm and leaves a hole can cause the most damage of any of these reasons that your tree might have a hole.
Because of the intensity of the way that a hole is created, when a limb is broken or ripped off, the size of the hole and the distressing nature of the damage can lead to a longer recovery time, if the tree can recover at all.
You may remember from above that trees can survive with holes as long there is a certain amount of structural integrity remaining. This integrity is created by having enough living, secure wood at the bottom of the tree’s trunk that can support the weight and functions of the rest of the tree.
So, in situations where a limb is ripped off and the decay begins to spread, or that lack of a limb causes an imbalance in the tree itself, the tree is at a greater risk.
That being said, trees survive storm damage all the time and helping your tree to recuperate by giving it fertilizer, water, spraying for insects, and more can be the difference between losing your tree and helping it back to stability.
7. Holes From Outdoor Projects
Doing outdoor projects is another way to cause some holes in the exterior of your tree and, while these warrant mention, they should be the most minuscule out of any holes you have on your tree.
Things like stapling or drilling into your tree’s exterior will cause slight distress, but as long as your tree is healthy and mature, you should not have to worry.
We don’t recommend creating holes in trees that are still young or appear to be old and brittle as this could cause your project to fall down if the bark cannot hold the weight of what you may be trying to connect to your tree.
One of the most common holes in your tree will come from tapping it for syrup.
Can A Tree Survive With A Hole?
Trees can survive with a hole. In fact, there is a greater chance that your tree will survive than not, especially when it comes to small holes like boring, tapping, and outdoor projects that will not cause much harm to your tree.
When it comes down to it, trees are resilient and can adjust to many hardships. Often, if the structural integrity of the tree has not been compromised, there will not be a reason for much concern.
Things change when a storm has broken off of a limb that was in some way vital to the structure of the tree.
This would be less a result of having a hole in the tree and more a result of the other part of the problem, which is that there is now a large limb missing and causing the tree distress.
Should You Take Action If Your Tree Has A Large Hole?
According to Oregon State University, the once-common practice of filling holes with cement can cause problems down the road, while doing nothing is also a solution.
While you may want to fill a hole or add some sort of caulking to avoid water damage, using cement is not something that most professionals recommend nowadays as it actually causes more harm to a tree.
So, unless you are deeply concerned and need help determining if your tree is still viable, your best course of action is to take steps to keep your tree as healthy as possible and see if it bounces back more naturally.
Your tree may have holes big or small, caused by an array of sources, but the most important thing to know is that your tree is very likely to recover from most of these incidents.
For now, we thank you for sticking with us as you work to continue your personal tree journey.
Until next time, friends!
Helliwell, D. R. (2007). A short note on effects of boring holes in trees. Arboricultural Journal, 30(3), 245-248.
Malone, C. (1976). Tapping the Sugar Maple–Learning and Appreciating. Communicator.
Wesołowski, T. (2011). “Lifespan” of woodpecker-made holes in a primeval temperate forest: A thirty year study. Forest Ecology and Management, 262(9), 1846-1852.