Woodpeckers are distinctive birds known for striking wood with extreme force, sometimes reaching speeds of 20 kilometers per hour. This rapid action is not random but serves multiple biological functions, allowing them to access resources and communicate in ways few other species can. Understanding the complex reasons behind this constant hammering reveals their unique ecological role.
Drilling for Food
Foraging is a primary driver for pecking. The bird uses its sharp, chisel-like beak to excavate holes through bark and into the wood, hunting for wood-boring insects and larvae. Once a meal is located, the bird employs its long, barbed tongue to extract the prey. Different species have unique feeding methods. Downy or Hairy species create irregular, deep holes as they drill for insects. In contrast, sapsuckers, such as the Yellow-bellied Sapsucker, drill neat, horizontal rows of shallow holes to access the tree’s flowing sap and trapped insects.
Excavating Nests and Roosts
Pecking provides shelter by creating cavities for both roosting and raising young. These larger holes are typically excavated in dead or decaying wood, which is softer than living timber. The process often takes several weeks of sustained drilling to complete a suitable nest cavity. The resulting cavities are unlined, and the bird lays its eggs directly onto wood chips. Woodpeckers generally create a new nest hole each breeding season, but they utilize existing holes for nightly roosting. Once abandoned, these old cavities become important habitat for secondary cavity-nesting animals, including owls, squirrels, and bluebirds.
Drumming for Territory and Mates
“Drumming” is the woodpecker’s primary form of long-distance communication, distinct from foraging or nesting. It involves rapid, rhythmic bursts of pecking on highly resonant surfaces to create a loud, carrying sound. This behavior is analogous to a songbird’s song, used to establish territory and attract a mate, usually during the spring breeding season. The rapid staccato can reach speeds of up to 16 to 17 strikes per second in species like the Downy Woodpecker. To maximize sound, birds select surfaces like metal gutters, utility poles, or dead limbs, which amplify their message. The rhythm and duration of the sequence vary between species, helping birds recognize rivals and partners.
The Anatomy That Prevents Head Trauma
The force generated during pecking subjects the woodpecker’s head to extreme deceleration, sometimes reaching 400 times the force of gravity. A key protective feature is the skull, which is designed for stiffness and rigidity, not shock absorption. The brain is small and tightly fitted within the skull, reducing movement upon impact. The robust hyoid bone, which supports the tongue, wraps completely around the back of the skull. This arrangement acts like a natural seatbelt, bracing the braincase before impact. Additionally, the outer layer of the upper beak is slightly longer than the lower beak, promoting optimal force transmission. This specialized anatomy ensures that the impact force is efficiently transferred through the body, preventing traumatic brain injury.
Keeping Woodpeckers Off Your Home
Woodpeckers sometimes target human structures, either detecting insects beneath the siding or seeking a resonant surface for drumming. Mitigation begins by checking for underlying insect infestations, as eliminating the food source can resolve the issue. If the damage is caused by drumming, the bird is usually seeking a mate or defending territory. Humane deterrents focus on visual or physical exclusion. Hanging reflective Mylar tape, aluminum foil strips, or old compact discs near the affected area can visually startle the birds, especially when the objects move in the wind. Physical exclusion, such as installing lightweight bird netting from the eaves down to the ground, is highly effective as it prevents the bird from making contact with the structure. Finally, filling and painting existing holes immediately can discourage repeat visits to that site.