Contrary to popular belief, woodpecker skulls do not act as shock absorbers, but rather as hammers, so as not to suffer brain damage when drilling holes in trees.
In fact, new calculations from research published in Current Biology show that any shock absorption would impede peak-pecking abilities.
“By analyzing high-speed video of three woodpecker species, we found that the woodpeckers do not absorb the shock of impact with the tree,” says Sam Van Wassenbergh from the University of Antwerp.
No risk of concussion
Van Wassenbergh and colleagues first quantified impact decelerations during pecking in three woodpecker species. They used the data to build biomechanical models, which led them to conclude that any impact absorption of the skull would be disadvantageous to the birds.
But if their skull doesn’t act as a shock absorber, are the repeated furious pecks putting their brains at risk? Turns out not. While the deceleration shock with each peck exceeds the known threshold for concussion in monkeys and humans, the small brains of woodpeckers can withstand it.
Van Wassenbergh says woodpeckers could make a mistake, for example, by pecking at metal with all their might. But their habitual pecking of tree trunks is usually well below the threshold to cause a concussion, even without their skulls acting as hard hats.
“The lack of shock absorption does not mean that their brains are at risk during seemingly violent impacts,” says Van Wassenbergh. “Even the strongest blows of the more than 100 pecks that were analyzed should be harmless to woodpecker brains, as our calculations showed lower brain loads than concussed humans.”
Demystify the myth
The results refute the long-held theory of shock absorption, which has been popularized in the media, books, zoos and more, Van Wassenbergh says. “When filming woodpeckers in zoos, I’ve seen parents explain to their children that woodpeckers don’t get headaches because they have a built-in shock absorber in their heads,” he says. “This myth of shock absorption in woodpeckers has now been disproved by our findings.”
From an evolutionary perspective, he says the results may explain why there are no woodpeckers with much larger heads and neck muscles. While a Pileated Woodpecker might be able to peck more powerfully, concussions would likely cause it significant problems.
The findings also have practical implications, he adds, given that engineers have already used the anatomy of the woodpecker’s cranial skeleton as inspiration for the development of helmets and shock-absorbing materials. New findings show that this is not a good idea, given that the peak anatomy minimizes shock absorption.
ee (Europa Press / Science Daily)