There are a few different types of birds that are known for pecking holes in trees. The most common culprits are woodpeckers, sapsuckers, and northern flickers.
Woodpeckers
Woodpeckers are likely the first bird that comes to mind when thinking about birds that peck holes in trees. They use their strong, chisel-like beaks to hammer away at tree bark to get to insects and larvae hiding underneath. This pecking behavior creates the characteristic holes and cavities that woodpeckers are known for.
There are over 200 species of woodpeckers worldwide. Some of the most common North American species that create holes in trees include:
- Downy Woodpecker
- Hairy Woodpecker
- Red-bellied Woodpecker
- Northern Flicker
- Pileated Woodpecker
Woodpeckers peck holes in both live trees and dead trees. They tend to favor trees that are already infested with insects that they can feed on. Certain species prefer different types of trees – oaks, maples, aspens, and conifers like pines and spruces are all common targets.
Sapsuckers
Sapsuckers, like the yellow-bellied sapsucker, also drill holes in trees. However, they have a different motivation than woodpeckers. Rather than excavating prey from under the bark, they drill orderly rows of shallow holes called sap wells to access the nutrient-rich sap that flows through the inner bark (phloem) of the tree.
Sapsucker holes are usually small (1/4 inch diameter) and are closely clustered together in horizontal or vertical rows. These sap wells allow them to lap up sap using their brush-tipped tongues. Preferred tree species include birches, maples, hemlocks, and hickories.
Northern Flickers
The northern flicker is a type of woodpecker that also drills holes in search of food. They forage primarily on the ground for ants but occassionally peck into trees for larvae and other insects. Flickers create large rectangular holes, typically in dead trees or on recently dead branches.
Flickers are unusual among woodpeckers because they mainly feed on ants harvested from the ground. They use their long, barbed tongue to lap up ants. When flicker holes are present, it usually means the tree already had carpenter ant or termite infestations.
Why Do These Birds Peck Holes in Trees?
Woodpeckers, sapsuckers, and flickers all create holes in tree trunks and branches for food. The holes provide access to:
- Insects and larvae living under the bark or inside the tunnels they create
- Sap in the case of sapsuckers
- Cavities for nesting and roosting
In addition to feeding, woodpeckers also excavate holes for nesting and roosting. They typically roost in tree cavities overnight. Many species also use tree hollows to raise their young. The holes provide protection from predators and insulation from weather.
Identifying the Holes
To figure out what kind of bird might be making holes in your trees, look for these identifying signs:
- Woodpeckers – irregularly shaped holes, often with ragged edges; holes may be deep and lead to long tunnels under bark
- Sapsuckers – neat, shallow, round or rectangular holes, arranged in horizontal or vertical rows
- Northern Flickers – large rectangular holes, 2-3 inches tall and several inches wide; holes tend to be in dead trees or branches
Woodpecker holes are often surrounded by “sap rings” – discolored bark stained by the sap that oozed from the hole. Flicker holes have very smooth edges and cylindrical inner walls, while woodpecker holes have irregular, jagged edges.
The size and shape of the holes can indicate what species may have made them. Larger holes are more likely pileated woodpeckers. Very small holes may be from downy woodpeckers. Checking for these clues can help identify the bird responsible.
Damage or Benefits to Trees?
There’s debate over whether woodpeckers help or harm trees when they peck holes.
Potential benefits:
- Feed on tree-damaging insects like beetle larvae
- Create habitat for other wildlife when they excavate nesting cavities
Potential drawbacks:
- Can allow decay fungi into the heartwood of the tree
- Create entry points for insects that can lead to more decay
- Cause sap flow that attracts insect pests
Most experts agree that healthy trees can withstand limited woodpecker damage. But trees already under stress from disease, insect infestations, or other wounds may suffer decline and dieback when woodpeckers peck holes in them. Keeping trees healthy is the best defense.
Preventing Woodpecker Damage
To stop woodpeckers from damaging trees, try these tactics:
- Wrap trunks with burlap, hardware cloth, or mesh
- Install plastic owls or shiny ribbon to scare them off
- Apply repellent pastes with capsaicin pepper or polybutene
- Attach Mylar balloons or aluminum pie pans near holes
- Plug existing nest holes to discourage reuse
- Use loud sounds, clapping, or water spray to frighten them away
The only permanent solution is to identify and eliminate any underlying insect infestations in the tree that are attracting woodpeckers. Otherwise they are likely to persist in pecking holes. Maintaining healthy, vigorous trees is the best deterrent.
Conclusion
When it comes to mysterious holes pecked into tree trunks, woodpeckers and their relatives are usually the culprits. They create these cavities mainly in search of food – either insects beneath the bark or sappy sap in the case of sapsuckers. Their pecking can occasionally cause damage, but healthy trees with intact bark typically survive limited woodpecker damage. Deterring them and improving tree health are the best ways to prevent problematic woodpecker pecking.