Why don't woodpeckers get brain damage?  Research presents an intriguing new hypothesis

Why don’t woodpeckers get brain damage? Research presents an intriguing new hypothesis

Forced to spend their days banging their tiny skulls into the sides of trees in search of buried bites, woodpeckers should have developed a trick or two to avoid brain damage. That’s how you would think.

A new study of the woodpecker’s biomechanics has cast doubt on speculation that the tiny chisel-headed bird avoids turning its brain to pulp with fancy shock-absorbing adaptations.

Rather, his brain might just be too small to care.

“By analyzing high-speed videos of three species of woodpeckers, we found that woodpeckers do not absorb the impact when hitting the tree,” says Sam Van Wassenbergh, biomechanics researcher from the University of Antwerp in Belgium.

Anyone who has ever seen or even heard the machine gun fire of a woodpecker’s distinctive knock will appreciate the physics involved.

With a staggering 20 head movements per second, members of some species can experience forces of up to 1400 g. Compare that to the meager 90 to 100g that can cause a human concussion and it’s easy to imagine the kind of trauma that could occur in this tiny skull.

Previous research has pointed to a variety of body modifications that could help reduce the effects on the woodpecker’s brain tissue, such as: B. spongy, shock-absorbing bones and neck muscles.

While these features appear to be engineered to absorb a blow, proving that they successfully reduce forces when the woodpecker’s head is rapidly accelerated and decelerated is a challenge.

The question also arises as to whether woodpeckers even bother with security features. Their small brains and tight skulls leave little room for rattling around.

More than a hundred high-speed videos of six woodpeckers representing the species were used in this study Dryocopus martius, Dryocopus pilatusand Dendrocopos majorVan Wassenbergh and his team carefully measured the delay in their eyes when their beaks struck wood.

Since the eyeball is a fairly adequate proxy for the squishy interior, the researchers were able to calculate the physics of a slowing skull.

The entire head turns out to move as a unit, with small variations in peak delay between the eye and the beak.

“Their heads basically work like stiff, solid hammers when they’re pecking,” says Van Wassenbergh.

Biomechanical models built on data gathered from frame-by-frame analysis of their videos only further confirmed that there was not much shock absorption between the tip of the beak and the contents of the skull.

All these specialized bone structures in this case do not even deform and absorb the energy of each impact, but resist fracture.

This makes the birds’ work more effective and efficient. “If the beak absorbed much of its own impact, the unfortunate bird would have to hit even harder,” the researchers explain.

While one study suggests the birds can suffer the effects of lifelong headbanging, simulations performed by Van Wassenbergh and his team on the intracranial pressure of the woodpecker’s skull suggest that constantly squeezing and shoving at such small brains isn’t enough to do anything Seriously anyway.

Woodpeckers just don’t need to bother with all those safety features.

“The lack of shock absorption doesn’t mean their brains are at risk during what appears to be violent impacts,” says Van Wassenbergh.

“Even the strongest shocks from the more than 100 analyzed picks should still be safe for the woodpecker’s brain, since our calculations have shown that the brain load is lower than that of people who suffer a concussion.”

The results help explain why woodpeckers never grew much larger than about half a meter (about 22 inches) in length. While a muscularly feathered jackhammer could drill out larger meals, their heavier brains wouldn’t take the pressure.

This means that although woodpeckers have small brains, they are not that dumb.

This study was published in Current Biology.

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