Hammer Time

Woodpecker study reveals the secret behind the birds' astonishingly hardy skulls

They’ve simply evolved to take frequent blows to the head.

Robert Shadwick & Erica Ortlieb (University of British Columbia)


Cars and bike helmets are designed to crumple during crashes.

Without these shock-absorbing properties, our bodies would be crushed on impact.

But woodpeckers, on the other hand, effortlessly withstand repeated impacts without bashing their skulls.

One prevailing explanation is that their skulls absorb shock, like a helmet, to help the birds avoid concussions and other injuries.

Hal Beral/Corbis/Getty Images


But researchers writing this week in the journal Current Biology demonstrate that the bird’s head bones actually don’t work the same way that a helmet does.

Instead, the researchers compare woodpecker heads to solid hammers, which give them the power to penetrate trees with considerable force.

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Erica J. Ortlieb (University of British Columbia)

For the study, they recorded three species of woodpeckers hammering away at hard surfaces in the laboratory to get a closer look at their head motions.

Here’s a pileated woodpecker slamming its beak into the wood in slow motion.

Robert Shadwick & Erica Ortlieb (University of British Columbia)

Christine Böhmer (Christian-Albrechts-Universität zu Kiel) and Anick Abourachid (Muséum National D'Histoire Naturelle)

Then, the researchers wanted to get a closer look at the spongy bone between woodpecker beaks and skulls — a prime candidate for shock absorption.

Erica Ortlieb & Robert Shadwick (University of British Columbia)

So the research team made some computer models of woodpecker heads where the center was squishy and others where it was more solid.

The top animation shows a solid woodpecker head, and the bottom shows one with a shock-absorbing center. Notice how the bottom one doesn’t penetrate the wood as deeply.

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Hal Beral/Corbis/Getty Images

In order for woodpeckers to efficiently peck into wood, the whole head has to remain pretty solid during impact, the researchers observed.

So, that spongy bone isn’t absorbing shocks as much as previously thought.

Instead, it appears woodpeckers just evolved to take blows to the head much more easily than humans.

Robert Shadwick & Erica Ortlieb (University of British Columbia)

Their tiny skulls and brains can withstand much more pressure than ours, meaning that it's harder for the birds to give themselves concussions.

Sam Van Wassenbergh (Universiteit Antwerpen)

This could also explain why woodpeckers the size of chickens or ostriches don’t exist.

Larger head and neck muscles might give the birds the ability to pound trees with greater force, but too much force could backfire and damage the brain.

André Gilden/Moment/Getty Images

The hardness of a surface and the speed of pecking could also influence how much force a bird could take, researchers write.

But as for everyday drilling and drumming, woodpeckers seem to have evolved to take the pressure unlike any other group of birds.

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