No Armor! Instead, Woodpeckers Mimic a Hammer to Avoid Injuring Their Heads

Some animals possess armors to defend themselves against enemies such as pangolins, hedgehogs, and armadillos.

Others have armors for protection against their own deadly weapons, such as the bigclaw snapping shrimps. These shrimps wear orbital hoods to safeguard their eyes and brain from the shock waves they produce by snapping their claw in order to easiy catch their prey.

Photo: YouTube/miOttawa

This kind of protective mechanism was what a team of European and Canadian researchers expected to find on woodpeckers.

“What this bird has to do during the entire day is dig holes into the wood. It’s very important that this business be very efficient,” said Sam Van Wassenbergh, an evolutionary biomechanicist at the University of Antwerp in Belgium and lead author of this new study.

However, in his point of view, if the woodpecker has a protective mechanism that makes the bird absorb some of the force it applies on a tree trunk, it would mean that the bird must peck more energetically in order to create holes. “So the more you think about it, the less it made sense that there was any shock absorption going on,” added Van Wassenbergh.

Photo: YouTube/miOttawa

And so, he and his colleagues decided to test three species of woodpeckers to find out the secret of these birds’ formidability. Using high-speed video, they tracked the motion of the various parts of these woodpeckers’ heads. Based on their hypothesis, there should be a slower deceleration of the birds’ braincases compared with their beaks upon impact with the wood they were pecking.

None! This means woodpeckers have no protective armors to protect their heads from concussions and other injuries even though they spend their lives pecking holes on tree trunks like a stiff hammer.

So, what is the secret behind this armorless, hammer-like pecking?

The researchers made use of simulations to measure the impact on the woodpeckers’ brains as they peck on tree trunks like a stiff hammer. Then, they used the data to compare with the human thresholds for concussion-causing forces.

Photo: YouTube/miOttawa

They found out that since the length of a woodpecker’s brain is 7 times smaller than that of a human being, it can withstand 7 times the force that causes human concussions.

Nevertheless, repeated subconcussive shocks can still inflict injuries such as chronic traumatic encephalopathy (CTE), which football players in offensive lines usually suffer.

Hence, the researchers were inclined to think that woodpeckers may have some physiological mechanisms that protect their brains from repeated subconcussive shocks. According to the study, steroid hormones like estrogens and androgens may have a protective influence on the woodpeckers’ brains.

Well, it’s another woodpecker mystery that we’ll be excited to get unraveled!

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