The rapid, percussive striking of a woodpecker’s bill against wood is one of the most recognizable sounds in nature, but this action, commonly called pecking, is not a single behavior. It is a versatile technique that serves three biological purposes. The meaning of the pecking depends entirely on the rhythm, location, and force the bird applies to the tree. Observing these subtle differences reveals whether the woodpecker is hunting for food, communicating a territorial message, or constructing a home.
Foraging for Meals
The most common reason for a woodpecker to strike wood is to locate and extract prey hidden beneath the surface. These birds are insectivores, using their strong, chisel-like bills to access wood-boring larvae, grubs, and ants that live in the bark or decaying wood. Foraging pecking is typically a slower, more deliberate, and erratic series of strikes focused on a small area, often resulting in irregular, chipped-out holes.
Woodpeckers detect food in two primary ways: they may visually search for small insect entrance holes, or they may use auditory cues, listening for the faint sounds of invertebrates moving within the timber.
Some species, such as sapsuckers, drill small, shallow, organized holes to reach tree sap. The sticky fluid provides energy, and the birds also consume insects trapped in the sap wells. Acorn Woodpeckers use their pecking ability to create storage sites, drilling holes in trees to cache hundreds of nuts. The goal is always to create an opening that allows the bird to use its long, barbed tongue to spear or lap up the meal.
Drumming for Communication and Territory
When a woodpecker produces a loud, rapid, and rhythmic burst of strikes, it is engaged in drumming. Drumming is a form of auditory communication used to attract a mate and declare territorial boundaries. This behavior is seasonal, occurring most frequently in late winter and spring during the breeding season, and is performed by both male and female woodpeckers.
The bird selects a highly resonant surface to amplify the sound, which can travel a distance through the forest. Woodpeckers frequently choose dead limbs, hollow trunks, or man-made structures like metal gutters and utility poles. For example, a Downy Woodpecker may strike a surface 16 to 17 times per second, creating a distinct, rapid roll that can be used to identify the species. This rapid, consistent rhythm differentiates drumming from the slower pecking used for finding food.
Excavating Cavities for Shelter
A third purpose for pecking is the excavation of cavities. Woodpeckers are classified as primary cavity excavators because they create these homes, unlike other birds that must rely on existing holes. These cavities are distinct from foraging holes, being much larger and deeper, often extending 45 centimeters into the tree for a nesting chamber.
The birds select dead or dying trees, known as snags, or parts of live trees where the heartwood has softened from decay, making the excavation process easier. A pair of woodpeckers will construct a new nest cavity each year, an effort that can take several weeks. These abandoned cavities are ecologically important because they provide shelter for numerous other wildlife species, called secondary cavity users, such as owls, squirrels, and various smaller birds that are unable to excavate their own homes.