The woodpecker’s head acts as a hammer and not a helmet

July 15 () –

Contrary to popular belief, woodpecker skulls do not act as shock-absorbing helmets, but rather as hammers, so as not to suffer damage to their brains by drilling holes in trees.

In fact, new calculations from research published in Current Biology show that any shock absorption would hamper the pecking abilities of woodpeckers.

“By analyzing high-speed video of three species of woodpeckers, we found that woodpeckers do not absorb the shock of impact with the treesays Sam Van Wassenbergh of the University of Antwerp.

Van Wassenbergh and colleagues first quantified impact decelerations during pecking in three species of woodpeckers. They used the data to build biomechanical models, which led them to the conclusion that any impact absorption of the skull would be disadvantageous for the birds.

But if their skulls don’t act as shock absorbers, does repeated furious pecking put their brains at risk? Turns out not. While the deceleration shock with each peck exceeds the known threshold for a concussion in monkeys and humans, the smaller brains of woodpeckers can withstand it.

Van Wassenbergh says that woodpeckers could make a mistake, for example, by pecking at metal with all their might. But their habitual pecking at tree trunks is generally well below the threshold for causing a concussion, even without their skulls acting as protective helmets.

“The absence of shock absorption does not mean that their brains are in danger during seemingly violent impacts,” Van Wassenbergh says. “Even the strongest blows out of the more than 100 pecks that were analyzed should be safe for woodpecker brains, as our calculations showed brain loads that are lower than those of concussed humans.”

The findings refute the longstanding theory of shock absorption, which has been popularized in the media, books, zoos and more, says Van Wassenbergh. “While filming woodpeckers in zoos, I’ve seen parents explain to their children that woodpeckers don’t get headaches because they have a shock absorber built into their heads,” she says. “This myth of shock absorption in woodpeckers has now been disproved by our findings.”

From an evolutionary standpoint, he says the findings may explain why there are no woodpeckers with much larger heads and neck muscles. While a larger woodpecker might be able to peck more powerfully, concussions would probably cause them major problems.

The findings also have some practical implications, he adds, given that engineers have previously used the anatomy of the woodpecker’s cranial skeleton as a source of inspiration for the development of helmets and shock-absorbing materials. The new findings show that’s not a good idea, given that the woodpecker’s anatomy minimizes shock absorption.

Van Wassenbergh notes that another recent study by his team showed that woodpeckers’ beaks often get stuck, but the birds quickly free themselves by alternating the movement of the upper and lower halves of their beaks. They are now studying how the shape of the beak is adapted for pecking.