Woodpeckers "strain and quack" like athletes to intensify the beak strike

A new study published in the Journal of Experimental Biology has shown that these birds literally turn their body into a living hammer, tensing the muscles of the head, neck, abdomen and tail to keep the body stationary and direct all the energy of the blow into the beak.

Scientists from Brown University (USA) and the University of Münster (Germany) studied eight woodpeckers and found that for a powerful blow, the birds not only tense their muscles, but also synchronise their breathing with the movement, as professional tennis players do, emitting a short "sigh" or "lurch" when hitting. This breathing helps to stabilise the body and increase the power of the stroke.

A team of researchers led by Nicholas Antonson and Matthew Fuchsjager used high-speed cameras and sensors to record the activity of muscles in the neck, head, abs, tail and legs during beak strikes on hard wood. Variations in airway pressure and the volume of air passing through the vocal cleft were also measured.

The results showed that the muscles of the front of the neck and hip flexors play the main role in the "striking motion" - they give the woodpecker's body a forward acceleration when it strikes. The other muscles maintain stability: the muscles at the base of the skull hold the head in position, the abdominal muscles stabilise the torso, and the tail muscles act as shock absorbers, helping the body to rest on the tree trunk at the moment of contact.

Essentially, the woodpecker turns itself into a one-piece structure that works like a hammer mechanism.

Scientists have also noticed that woodpeckers regulate the force of the blow. When they drill into the wood, the muscle contractions are stronger and the energy of the blow is higher. And when there is a slight "knock" - for example, when the birds exchange signals - the muscle force decreases.

The most surprising discovery was the breathing of woodpeckers: each blow is accompanied by a sharp exhalation - "quacking", which increases the contraction of the muscles of the body. This helps increase the force of the blow, similar to the way athletes exhale when performing heavy movements.

"This breathing increases trunk stability and impact efficiency," explains Antonson.

The researchers also found that when chiselling more gently, woodpeckers take mini-breaths of about 40 milliseconds between beats, reaching a frequency of up to 13 beats per second. This breathing is perfectly synchronised with each beak movement.

In this way, woodpeckers use their entire body - from the tip of their beak to their tail- to maximise power and precision. But, unlike tennis players, we can't hear their "quacking" - it is drowned out by the characteristic drumming.