When woodpeckers go to work ‘drilling’ for the insects they rely on for food, we can clearly see that they do significant damage to the tree trunks they peck. Observing this behavior, it’s a reasonable question to ask: “Do Woodpeckers Kill Trees?”.
In this article, we’ll be answering this question using data that biologists and arborologists have discovered. Hopefully, in learning more about the ‘true’ damage that woodpeckers cause, you can develop a newfound appreciation for these fascinating and resourceful birds.
So, do woodpeckers kill trees? Woodpeckers do minor damage to individual trees but are extremely critical in helping a forest stay healthy. So, overall, woodpeckers are highly beneficial for trees as a whole. Let’s take a closer look at why!
Why Are Woodpeckers Pecking On Trees?
To understand the impact of woodpeckers on trees it is important to understand why they peck. Pecking activities typically fall into three categories:
Let’s look at each of these activities to understand how trees are impacted.
Do Woodpecker Feeding Activities Hurt Trees?
When a tree becomes damaged or diseased it can become infested with ants, tree borers, beetles, etc. These insects will eat the healthy portions of the tree from the inside and will often eventually cause the tree to die.
Many varieties of woodpeckers (Pileated, Red Bellied, Red Headed, etc) feast on these insects and will tear the bark off the tree and drill down into the wood in an effort to find more bugs to eat.
Watching a woodpecker tear into a tree to eat insects looks incredibly damaging but you have to remember, the only reason that the woodpeckers are there is because the tree was already in trouble. It is not a stretch to imply that the woodpeckers are doing the tree a favor by removing the parasites that will eventually kill it.
There are Reports of Sapsucker Woodpeckers Killing Trees
There is a class of woodpeckers known as “sapsuckers” (Yellow Bellied, Red Breasted, Red Naped) and there are mixed answers about their impact on trees.
Sapsuckers drill small holes into the bark of the tree from which they drink the flowing sap. The holes are not deep but the sapsuckers create a LOT of them.
It’s easy to spot the woodpecker damage from Sapsuckers because the holes are almost always regularly spaced in straight vertical or horizontal rows. Sapsuckers like trees with thin bark such as apple or paper birch.
The general consensus is that these small “woodpecker holes” do not impact the health of large trees. However, if the birds aggressively feed on small trees then the holes can potentially “girdle” the tree and kill it. The video below provides a more detailed discussion.
The information in the video is supported entirely by a publication from the Pacific Northwest Pest Management Handbook (source). While an interesting study for the US Forestry Service in 1969 indicated that sapsuckers were indeed capable of killing trees when they fed aggressively on particular trees current arborologists agree that it is rare for them to damage trees that severely (source).
[Fun Fact Related to Tree Sap and Woodpeckers: One species of woodpecker in particular—the Red-Cockaded Woodpecker—has developed a curious tactic to stop hungry rat snakes from climbing the trees it uses to feed and nest. This clever bird will intentionally drill into a tree enough to release just the right amount of sap required to thwart the snake from being able to slither up the tree. Fascinating!] (source)
Does Woodpecker Drumming Hurt Trees?
Woodpeckers are unable to produce birdsong and as a replacement will often “drum” on a tree as a form of communication (source). Below is an excellent example of what drumming sounds like.
Drumming helps woodpeckers establish and defend territories, attract mates and deter predators (source). To accomplish these goals the woodpecker wants the drumming to be as loud as possible.
When a woodpecker is drumming on a tree it likes to find a dead, hollow branch to use as the empty cavity makes more noise. Check out that video above again and you will see the woodpecker is drumming on a hollowed out dead branch.
This type of activity does no damage to trees.
Do Woodpecker Nesting Activities Hurt Trees?
Here is where things get interesting!
Intuitively one might think that when a woodpecker creates a cavity inside a tree to create a nest that it must be harmful to the tree. However, there are two aspects about this activity that not only minimize the harmful impact but actually make it beneficial.
The first thing to realize is that the wood on the INSIDE of a tree, called “heartwood”, is already dead (source). The only parts of the tree that are living and growing are the outer portions knows as “sapwood”.
When a woodpecker excavates a cavity for a nest it makes a small hole in the living sapwood and a huge cavity in the heartwood. The whole in the sapwood is not large enough to cause any meaningful damage and the cavity in the dead heartwood goes unnoticed by the tree!
The second thing to realize is that while it takes woodpeckers weeks to create a cavity nest they typically only use it to raise a single clutch of babies (source). Once the woodpeckers abandon their cavities these nests are provide desperately needed shelter for squirrels!
Woodpeckers are vitally important in providing shelters for all types of cavity nesting animals, squirrels included. Squirrels use these cavities for winter shelter and to raise their pups. In turn, squirrels are vitally important in spreading acorns and other nuts which helps create new trees and a healthy forest!
What Do Woodpeckers Eat?
What are woodpeckers drilling for in trees? Besides communicating, woodpeckers are looking for their next meal.
Woodpeckers eat a variety of foods such as ants, beetles, bees, sunflower seeds, carpenter ants, insect larvae, fruits, and more.
So, Are Woodpeckers Harmful to Trees?
The interaction between woodpeckers and trees is complex. While woodpeckers do incur some damage to trees the impact is minimal and rarely fatal to the tree.
In the bigger picture, woodpeckers are an essential part of a healthy forest as they provide nesting sites for squirrels and other animals that transport and store nuts, some of which eventually become new trees!
Photo Credit: Paul Stein on Flickr