How Woodpeckers Turn Their Entire Bodies Into Peck Machines

These birds’ drilling approach is more like a game of extreme tennis than weightlifting

By Rohini Subrahmanyam edited by Sarah Lewin Frasier

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The picks operate at an extreme level, piercing solid wood with forces more than 30 times their own weight and drilling up to 13 times per second. How do they never miss a beat during hit your head so hard?

It turns out that the birds strain their entire bodies to break the wood, letting out short, explosive grunts with each strike, report Nicholas Antonson, a biologist at Brown University, and his colleagues. in the Journal of Experimental Biology. “In a sense, woodpeckers really are nature’s hammer,” Antonson says.

To study how birds tap, researchers first humanely captured eight wild downy woodpeckers and carefully inserted electrodes into their muscles in the laboratory. The electrodes powered a small, fitted backpack that recorded electrical signals from muscle contractions when the birds pecked. They also tested whether woodpeckers held their breath during exercise (as weightlifters tend to do) or exhaled (like tennis players) while hitting wood by examining the flow of air through the birds’ air sacs, small balloon-shaped structures that help them inhale and exhale. By matching these measurements with high-speed videos, the scientists tracked the woodpeckers’ hits every four milliseconds.

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Instead of using a single muscle to control the action, the woodpeckers activated “all the muscles from head to tail,” Antonson says. The birds used their powerful hip flexors to move forward, tightened their tails and abdominals to prepare for the attack, and stiffened the back of their head and neck upon contact, the same way you might stiffen the back of your wrist when driving a nail. They then engaged a different set of hip and neck muscles to move backwards.

The birds also perfectly paired their beaks with sharp exhalations “as another way to stabilize their core muscles and resist these strikes,” says Antonson. “Being able to exhale 13 times per second and inhale in the order of 40 milliseconds is truly impressive.” Songbirds, which are not closely related to woodpeckers, are the only other birds known to so precisely time their breathing, which they do while singing.

“Pecking is a whole-body exercise,” says Nicole Ackermans, a biologist at the University of Alabama who studies brain damage in woodpeckers and headbutting sheep. Coordinating “micro-breaths” with muscle contractions and creating “this hammer-like structure throughout their body is such a unique approach,” she adds.