Woodpeckers are common birds recognized for their distinctive interactions with trees. Their activities involve pecking, drilling, and drumming on woody surfaces. These behaviors serve various purposes, from seeking food to establishing territories. Understanding these interactions clarifies why woodpeckers engage with trees.
Reasons Woodpeckers Interact with Trees
Woodpeckers engage with trees primarily for sustenance. They actively forage for insects like beetle larvae, ants, and other wood-boring invertebrates found beneath bark or within wood. Some species, known as sapsuckers, drill small wells to access tree sap, also consuming insects attracted to the liquid. Their diet can also include fruits, nuts, and seeds depending on seasonal availability.
Another significant reason for their tree activity is nesting and roosting. Woodpeckers excavate cavities, typically in dead or decaying wood, to create sheltered spaces for their young and for roosting. Both male and female woodpeckers participate in this excavation, which can take several weeks. The excavated wood chips often form a soft bed for their eggs within the cavity.
Woodpeckers also use trees for communication through drumming. This involves rapidly striking their bills against resonant surfaces, including hollow tree trunks, branches, or man-made structures like utility poles. Drumming primarily functions as a territorial display and a means to attract mates, similar to how songbirds use vocalizations. Different woodpecker species exhibit unique drumming patterns, which can aid in their identification.
Understanding Woodpecker Marks on Trees
The physical marks woodpeckers leave on trees provide clues about their activities. When foraging for insects, woodpeckers create irregular, scattered holes or excavated patches where they extract prey. These holes vary in depth, from shallow pecks to deeper excavations, depending on insect location within the wood.
Sapsuckers produce a distinct pattern of holes on tree trunks and branches. They drill small, precise holes arranged in neat horizontal or vertical rows, creating a grid-like appearance. These “sap wells” are used to collect sap, and the birds return to these sites repeatedly. These patterns differ from the more random holes made by wood-boring insects.
Nesting cavities are larger, often oval or circular holes leading to an excavated chamber within the tree. These are usually found in softer wood, such as dead or diseased portions of a tree. The size and shape of these entrance holes can vary by woodpecker species.
Marks from drumming are generally less visually distinct than foraging or nesting holes. They may appear as slight indentations or wear on the bark or wood surface. These marks result from rapid striking used for communication.
The Impact on Tree Health and the Ecosystem
Much woodpecker activity is benign or beneficial for tree health and the broader ecosystem. When woodpeckers forage for insects, they often target trees already infested with destructive pests like beetle larvae, acting as natural pest control. For instance, they can remove a significant percentage of emerald ash borer larvae from infested ash trees.
The cavities created by woodpeckers also serve an important ecological role. After woodpeckers abandon their nests, these excavated holes become homes for many other wildlife species, including squirrels, owls, and birds that cannot excavate their own cavities. These abandoned cavities are used for nesting, denning, roosting, or food storage, making woodpeckers important “ecosystem architects.”
However, certain woodpecker activities can lead to tree damage. Extensive sap-drilling by sapsuckers, especially on young or thin-barked trees, can girdle the tree, interrupting water and nutrient flow, potentially leading to weakening or death. The holes created can also provide entry points for wood-decaying fungi and bacteria, making the tree more susceptible to secondary issues. Woodpeckers frequently target trees already compromised by disease or insect infestations, so their activity can sometimes exacerbate existing problems.
Protecting Trees from Significant Damage
For homeowners concerned about extensive woodpecker activity, assessing tree health is a practical first step. Woodpeckers are often attracted to trees that are unhealthy or infested with insects. Addressing underlying issues like pest infestations can reduce woodpecker interest.
Various deterrents can discourage woodpeckers from specific trees. Visual deterrents, such as reflective tape, shiny objects, or reflective pinwheels, can be hung near affected areas to scare birds away. The movement and flashing lights from these objects mimic potential threats. Physical barriers, including netting, hardware cloth, or burlap, can be wrapped around vulnerable tree trunks to prevent access.
Habitat management can also mitigate damage. Ensuring trees are healthy and vigorous reduces their attractiveness to insect-foraging woodpeckers. Providing alternative food sources, such as suet feeders, or maintaining dead snag trees as alternative nesting or foraging sites, may redirect woodpecker activity. If woodpecker damage is severe or persistent, consulting a certified arborist is advisable for tailored solutions and tree care.