Woodpeckers are amazing birds that can hammer away at trees thousands of times per day without causing any damage. However, there has been some debate around whether extensive woodpecker damage can actually cause trees to fall. In this article, we’ll examine the evidence and arguments on both sides of this issue.
Quick Answers
Can woodpeckers cause healthy trees to fall? Generally no, woodpeckers cannot directly cause healthy trees to fall down through drumming alone. However, woodpecker damage can weaken trees over time, making them more susceptible to other factors like wind, disease, and rot that ultimately lead to tree failure.
Do woodpeckers make trees unsafe? Extensive woodpecker damage may compromise the structural integrity of trees, but does not necessarily make them unsafe. Arborists can assess trees for risks and provide recommendations for pruning or removal if they pose a hazard.
Should woodpecker holes be repaired? Filling woodpecker cavities is usually not necessary, but may be done for aesthetic reasons or to prevent further damage. Holes can be patched with wood filler, but woodpeckers may continue to excavate the repaired area.
The case for woodpeckers causing tree falls
There are some documented instances where woodpeckers appeared to directly contribute to tree failures. Here are some of the main arguments that extensive woodpecker activity can bring trees down:
- Woodpeckers can drill large, deep cavities that significantly weaken tree structure. In one case, a woodpecker nest hole was implicated in the collapse of an 80 foot tall pecan tree.
- Feeding holes from sicklebill woodpeckers were determined to be the primary cause of failure in a eucalyptus tree that crashed into a house.
- Woodpeckers often focus their feeding on trees that are already distressed or beginning to decay. This exacerbates structural weaknesses.
- The constant hammering from woodpeckers can loosen soil and shake roots, making trees more prone to blow-over.
- Woodpecker cavities allow water and fungal rot to get inside the tree, accelerating hollowness and decay.
In trees that are especially weakened, woodpecker damage may be the tipping point that leads to structural failure. Arborists recommend checking for signs of extensive woodpecker activity and monitoring compromised trees carefully.
The case against woodpeckers as a primary cause
While woodpeckers can certainly damage trees, most experts argue that they rarely directly cause tree failures on their own. Here are some of the counterpoints:
- Woodpeckers generally choose trees that already have internal decay and structural issues.
- Even large woodpecker holes account for minimal loss of wood strength relative to total tree biomass.
- Woodpeckers inflict surface damage, but don’t degrade the critical inner heartwood that provides key support.
- Drumming dissipates the hammering force and does not impart intense localized stress.
- Failed trees attributed to woodpecker damage typically have other factors like fungus, rot, and cavity nesters that led to greater weakening.
While woodpeckers may hasten the process, most trees would eventually fail even without woodpecker damage present. Healthy trees can generally tolerate extensive drilling, while woodpecker damage on unhealthy trees is more an effect than a cause of structural instability.
Documented cases of woodpeckers contributing to tree failures
There are documented instances where woodpecker damage has been implicated as a contributing factor in tree failures. Here are some notable examples:
- A 175 foot tall pine tree that crashed into an occupied condominium in Florida showed extensive pine beetle damage that woodpeckers had focused on, leading to catastrophic weakening of the trunk.
- A security camera captured footage of a utility pole that broke and fell following heavy woodpecker drilling activity in the preceding days.
- An 80 foot pecan tree collapsed suddenly in Tennessee, with arborists identifying substantial structural decay around large woodpecker nesting cavities as the primary cause.
- A massive eucalyptus tree crashed into a home in California after being extensively excavated by sicklebill woodpeckers feeding on beetle larvae.
These examples lend some credence to the idea that woodpecker damage can be the final blow to already vulnerable trees. However, it is difficult to definitively prove the woodpecker damage alone triggered the failure in otherwise healthy trees.
Factors that influence woodpecker tree damage
Not all woodpecker activity and tree damage carries the same risk for contributing to tree failure. Here are some key factors that affect the severity and consequences of woodpecker damage on trees:
- Tree health – Woodpecker damage has greater impact on trees that are old, diseased, or already structurally compromised.
- Size and location of cavities – Large, deep holes in critical parts of the trunk present more risk than smaller shallow holes in limbs.
- Species of woodpecker – Larger woodpeckers like pileated can do more damage than smaller ones like downy woodpeckers.
- Purpose of holes – Feeding holes tend to be shallower than nesting and roosting cavities.
- Presence of decay – Existing fungus and rot exacerbate the weakening from cavities.
- Fill in holes – Filling cavities prevents water collecting and further decay inside the tree.
Understanding these factors can help arborists assess the severity of woodpecker damage on a tree and whether preventive actions like pruning and reinforcement are warranted.
Protecting trees from woodpecker damage
If woodpecker damage is extensive, here are some methods that may stop additional woodpecker activity and prevent further degradation of tree structure:
- Installing bird netting or wrapping on affected areas
- Filling cavities with foam or wood putty
- Hanging shiny ribbons or aluminum pie pans near holes
- Applying insecticides if woodpeckers are feeding on beetles or larvae
- Using noise deterrents like clackers, banging pans, or ultrasonic devices
- Pruning away damaged limbs or branches
- Consulting an arborist about assessment, prevention, and risk reduction
However, it is important to note that deterring all woodpecker activity is difficult and usually not necessary. Limited superficial damage generally does not put a healthy tree at risk. Preventive measures should focus on discouraging further excavation of existing vulnerable areas.
When to be concerned about woodpecker damage
Most woodpecker activity does not require intervention. But it is prudent to be concerned if you observe these signs:
- Sudden increase in the number or size of holes
- Deep holes with substantial inward cracking in the trunk
- Holes located near the base, root collar or other critical support structures
- Liquid seeping from holes, indicating internal fungal decay
- Multiple large cavities in close proximity creating severely weakened areas
- Leaning, cracked or sagging limbs near damaged areas
If the tree already has issues like fungus, carpenter ants, cracks, or deterioration then even minor woodpecker damage warrants closer inspection. Check for any changes after major storms as well.
Professional tree risk assessment
In cases of extensive woodpecker damage, it is wise to have a certified arborist conduct a detailed tree risk assessment. This will check for:
- Presence of disease, fungus, rot, and hollowing in the trunk or branches
- Structural defects like cracks, weak branch unions, and cavities
- Insect infestations that can accelerate interior decay
- Degree of lean and root compromise that make blow-over more likely
- Options for cable bracing, bolts, or supports to reinforce weak areas
- Whether pruning of damaged branches or removal is recommended
The arborist can provide a report on the current condition of the tree and actions needed to reduce the risk of failure. This expert assessment gives peace of mind about whether the tree can be retained safely.
Conclusion
There is no definitive evidence that woodpecker damage alone directly causes otherwise healthy trees to fall down. Woodpeckers are likely drawn to trees already declining due to disease, age, and structural defects. Their cavity excavation can speed the progression of decay and weakness in compromised trees. So while extensive woodpecker activity is not necessarily fatal to trees, it should be viewed as a potential warning sign for further assessment and prevention. With proper actions guided by arborist evaluation, even significantly damaged trees can often be retained as safe features of the landscape.