Why Do Woodpeckers Peck Wood? Feeding, Nesting, Drumming

1. Pecking to find food

Most woodpeckers are insect hunters, and the richest food in a forest is hidden inside the wood: beetle larvae, carpenter ants, termites and other insects that tunnel through dead and dying trees. A woodpecker taps along a trunk, probably listening and feeling for hollow galleries, then chips away bark and wood to open them up.

Once a tunnel is exposed, the bird reaches in with its long tongue, which can be sticky, barbed or both, and pulls out the prey. The tongue is so long that it wraps around the skull when pulled back, as explained in how long is a woodpecker’s tongue?

Feeding holes vary a lot between species:

Feeding pecking is usually irregular: a series of taps and harder blows, with pauses to look and listen, rather than the steady roll of drumming.

2. Pecking to make a home

Almost all woodpeckers nest in holes they dig themselves. In spring a pair, often mostly the male, chisels out a round or oval entrance and then a deeper chamber below it, tossing out the chips. Big species can take several weeks to finish a nest; small species work faster in soft, rotting wood.

Most woodpeckers dig a fresh nest each year and also carve separate roost holes to sleep in, especially in winter. Excavating is slower and more deliberate than drumming, with the bird working steadily at one spot, and it often goes on for hours a day.

These holes matter far beyond the woodpecker family. Old woodpecker cavities become nests for owls, ducks such as wood ducks and goldeneyes, swallows, bluebirds, nuthatches and chickadees, and dens for squirrels and bats.

3. Drumming to send messages

Drumming is the woodpecker version of birdsong. Instead of singing, a woodpecker hammers rapidly on something resonant, such as a hollow branch, a dead trunk or a metal gutter, producing a rolling burst that can be heard a long way off. It is not trying to make a hole; it is trying to make noise.

Drumming tells rivals that a territory is taken, attracts and keeps in touch with a mate, and helps pairs coordinate around the nest. Both sexes drum in most species, and drumming is most frequent in late winter and spring.

Each species has its own drumming pattern, defined by the number of beats, the speed, the length of each roll and whether it speeds up or fades. Birders can often identify a woodpecker by its drum alone. The pileated woodpecker’s drum, for example, is deep, loud and relatively slow, while smaller species produce faster, higher rolls. Research suggests these rhythms are remarkably consistent across each species’ range.

Special cases: sapsuckers and acorn woodpeckers

Some woodpeckers peck for more unusual reasons.

Sapsuckers, such as the yellow-bellied sapsucker of eastern North America, drill rows of small, shallow holes called sap wells in living trees. They return again and again to lap up the sap and eat the insects attracted to it. Other animals benefit too: ruby-throated hummingbirds often feed at sapsucker wells in early spring.

Acorn woodpeckers of the western United States, Mexico and Central America drill hundreds or even thousands of small holes in a single tree, called a granary, and wedge an acorn into each one. A family group stores its winter food supply this way and defends the granary year after year, adding new holes as it goes. The same trees, and sometimes utility poles and fence posts, are used for generations.

Why do woodpeckers peck on houses?

Woodpeckers sometimes peck on buildings, and the reason is usually one of the three above:

• Drumming: gutters, downspouts, chimney caps and metal vents make wonderfully loud drums, especially in spring.
• Feeding: wooden siding can hide insect larvae, and the birds may dig after them.
• Nesting or roosting: cedar siding, eaves and wooden boards can look like a soft dead tree.

Repeated drumming in one spot early in the morning is almost always a territorial or courtship display, and it usually stops once the breeding season is under way.

How can woodpeckers peck without getting hurt?

All this hammering puts big forces on the head. Woodpeckers have a compact skull with stiff yet spongy bone, a small, tightly fitting brain and a strong, chisel-like bill. Pecks are very short impacts, and the bird closes a protective third eyelid, or nictitating membrane, just before each blow to shield its eyes from flying chips. Bristly feathers cover the nostrils to keep out dust.

The details are still being studied, and some popular explanations turn out to be wrong. The full story is in why don’t woodpeckers get headaches?