[Tweeters] A woodpecker's brain takes a big hit with every peck: study

[Nadine Drisseq]

https://www.npr.org/2022/07/14/1110581385/a-woodpeckers-brain-takes-a-big-hit-with-every-peck-study

https://www.cell.com/current-biology/fulltext/S0960-9822(22)00855-7

The brain of a woodpecker experiences a seemingly catastrophic impact every
time beak meets wood.

"When you see these birds in action, hitting their head against a tree
quite violently, then as humans we start wondering how does this bird avoid
getting headaches or brain damage," says Sam Van Wassenbergh
<https://www.uantwerpen.be/en/staff/sam-vanwassenbergh/>, a researcher at
the University of Antwerp in Belgium.

In the past, scientists have suggested
<https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(76)91477-X/fulltext>
the
bird's brain is protected from the impacts, perhaps by a skull that acts as
a cushion
<https://www.jstage.jst.go.jp/article/jsmea/49/3/49_3_390/_article>, or a
beak that absorbs some of the force, or a tongue that wraps around the
brain.

But Van Wassenberg wasn't convinced.

"Nobody has ever explained it very well, in my opinion," he says.

So Van Wassenbergh led a team that set out to settle the issue using high
speed video of woodpeckers in action.

"We went to four different zoos in Europe where they had woodpeckers and we
recorded them at very high frame rates, while they were pecking," he says.

The videos, part of a study published
<https://www.cell.com/current-biology/fulltext/S0960-9822(22)00855-7> in
the journal *Current Biology,* revealed some remarkable details.

For example, "they close their eyes at the moment they impact the wood,"
Van Wassenbergh says, to protect their eyes from splinters.

The videos also showed that woodpeckers' beaks often get stuck in the wood.
But they break free almost instantly, thanks to a clever beak design that
provides independent motion of the upper and lower beak.

What the videos did not show is any sign that the woodpecker's brain is
somehow cushioned.

"The way we see the head behaving is very rigid, like you would use a
hammer hitting wood," Van Wassenbergh says.

That means the organ repeatedly experiences deceleration that would cause a
concussion in a human brain. Yet the woodpecker brain emerges unscathed,
even after thousands of impacts in a single day.

That is possible because a woodpecker's brain *is* protected — not by
cushioning, but by its tiny size and weight, Van Wassenbergh says.

"An animal that has a smaller size can withstand higher decelerations," he
says. "That's a biomechanical law."

That idea was suggested
<https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.2006.00166.x>
in
2006 by Lorna Gibson, a professor of biomechanical engineering at MIT. Now,
it has been confirmed by Van Wassenbergh's high-speed video.

A woodpecker's brain is about 700 times smaller than a human brain. "So
that is why even the hardest hits we observed are not expected to cause any
concussion," Van Wassenbergh says.

Or even a headache.
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