How a woodpecker drills without becoming hopelessly dizzy?


A woodpecker drilling a tree.

The sound of rapid tapping catches your attention as you walk past a clump of trees.

Sure enough, there is a woodpecker drilling on a tree trunk, probably in search of insects or insect larvae. Or, it may be chipping out a hole for a nest.

This is a familiar sight and sound in many parts of the earth, for woodpeckers are found in all lands except Madagascar and the region of Australia.

In less than three seconds a woodpecker may bang its chisel-like bill some forty-four times against a tree trunk or a limb.

How can the bird endure all this pounding without becoming hopelessly dizzy?


The answer seems to lie in the design of the woodpecker’s head.

The space between the bird’s brain and the tough outer brain membrane is very narrow and, therefore, contains less fluid than the wider gap found in related birds that do not tap or drum.

This feature apparently serves to reduce fluid shock waves resulting from impact and vibration. Then, too, comparatively dense but spongy bone encases the. brain, preventing the movement of this vital organ.

Also, the spongy, elastic connective tissue joining the bones between the skull and the beak absorb shock, as do the large muscles that extend over the woodpecker’s head and behind each of its ears.

Besides controlling the movement of the tongue, these muscles act much like a shock absorber, cushioning the head and preventing it from rotating.

Other parts of the woodpecker’s body are likewise marvelously designed for activity—the legs, the feet, the tail and the tongue.

Take a look at the legs. They are short and strong, ideally suited for climbing in a vertical position.

The foot consists of four toes, with the second and third toes pointing forward and the other two facing backward.

The fourth toe can also be moved to the side and front. Each toe is equipped with a sharp curved claw.

Thus each foot can function as a pair of tongs, enabling the woodpecker to get a firm grip as it climbs on tree trunks, branches, cliffs or even on the walls of buildings.

The tail also contributes its part to the bird’s successful existence. It works well as a prop or a brace while the woodpecker hammers away.

The twelve strong feathers making up the tail are arranged like shingles, with one lying on top of another.

During the molting process, the unusually strong two central feathers are not lost until the others have grown back and are able to provide needed support for the woodpecker.

The tongue is yet another noteworthy feature of the woodpecker.

 It is attached to the hyoid, an apparatus of bone and elastic tissue that loops around the skull.

Certain muscles pull on the hyoid loops and thereby push the tongue out of the beak for a considerable distance.

In the case of the green woodpecker, the tongue may protrude up to four inches (10 centimeters) beyond the bill.

Flicking in and out of the beak, the extended tongue, covered with a thick layer of sticky mucus, can reach insects and larvae hidden away in intricate passageways.

In many varieties of woodpeckers, the tip of the tongue is horny and equipped with bristles.

With these bristles, larvae readily are impaled.

There are also woodpeckers with spoon-like tongues that terminate in a broad cluster of bristles, just the right design for scooping up ants and termites.

How does a woodpecker determine whether a meal is concealed beneath the bark of a tree?

Commonly, this is attributed to its keen sense of hearing.

After tapping and then pausing for a moment, the bird may be able to detect whether any insects have been disturbed.

Also, galleries made by insects doubtless produce a difference in sound in the woodpecker’s tapping.

The internal structure of its head may provide humans with the inspiration for better safety headgear in the future.

For the woodpecker, however, its excellent equipment is essential for life.