Bird brains: Smaller is better for preventing woodpecker concussions

Having a tiny brain is an advantage in life. At least if you’re a woodpecker.

While impolite humans throw around the word “birdbrain” as an insult, it seems that in the case of woodpeckers, it’s an evolutionary advantage.

It was commonly believed that brain damage in woodpeckers was prevented by the shock-absorbing properties of the creature’s skull. But a new study published in Current Biology suggests otherwise.

“They do not absorb the shock of the impact with the tree. Their heads basically function as stiff, solid hammers during pecking,” says the study’s lead author Sam Van Wassenbergh from the University of Antwerp, Belgium.

That, the research says, makes sense. If the skull had shock-absorbing properties, it would dissipate the head’s kinetic energy. And that would mean our poor woodpecker had to work much longer to drill into a tree trunk.

Instead, the forces exerted on the brain by this repeated motion and impact are insufficient to cause damage.

That’s good news for these birds which have an incredibly high, repetitive pecking output, as anyone who’s heard the clamour can attest.

How they worked it out

Van Wassenbergh’s team performed their analysis by calculating the impact decelerations from black (Dryocopus martius), pileated (D. pileatus) and great spotted (Dendrocopos major) woodpeckers and applying the data to build biomechanical models.

From this, they were able to debunk the idea that shock-absorption was a factor in play.

“I have witnessed parents explaining to their kids that woodpeckers don’t get headaches because they have shock absorbers built into their head,” Van Wassenbergh says.

“This myth of shock absorption in woodpeckers is now busted by our findings, and the absence of shock absorption does not mean their brains are in danger during the seemingly violent impacts.

“Even the strongest shocks from the over 100 pecks that were analysed should still be safe for the woodpeckers’ brains, as our calculations showed brain loadings that are lower than that of humans suffering a concussion.”

Woodpecker research ongoing

Van Wassenbergh’s team has been studying the properties that allow woodpeckers to efficiently chip away at tree trunks for several years, including recently publishing detail on how the birds avoid getting stuck in trunks.  

This is possible despite their hammer-and-nail approach to wood penetration thanks to their ability to move their upper and lower beaks independently.

They’re no slouches either – this process of “walking” their chisel-like beaks out from tree wood takes place within 70 milliseconds.

The Antwerp team is now investigating how their beaks’ shapes are optimised for woodpecking.

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