‘Woodpecker does not have a shock absorber’

The woodpecker’s head acts more like a hard iron than a soft rubber mallet, according to research from the University of Antwerp.

Bam bam bam! Just looking at a throbbing woodpecker gives you a spontaneous headache. Still, the birds themselves are fine. It was long thought that it was due to a built-in shock absorber. But a new study in Current biology by a Flemish research team from the University of Antwerp shows that this is not the case.

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Safety helmet?

Woodpeckers crash their sharp beaks against a tree trunk with a g-force of about 50 g. They do this to make holes and then scoop up insects with their long, narrow tongues. They also use the ability to make nests, lure a mate and mark a territory.

For a long time, scientists thought the birds would have some sort of resilient safety helmet to absorb the blows. To prevent knocking leading to brain damage. The team from Antwerp, led by Sam van Wassenbergh, decided to test this hypothesis by using a high-speed camera to capture six beating woodpeckers of three different species.

A CT scan of a woodpecker’s head. According to one hypothesis, the yellow part would serve as a kind of shock absorber. This now appears to have been refuted by the current investigation. (C © hristian-Albrechts-University in Kiel) and Anick Abourachid (National Museum of Natural History)

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The researchers calculated the impact delay on more than a hundred choices. This is a measure of the head that comes to rest against the tree trunk immediately after an acceleration (leading the head to the tree). Analyzes of those recordings showed that the beak slowed just as fast as the skull with the brain. In other words: there is little or no shock absorption.

However, the woodpecker does not get brain damage. How? A biomechanical computer model – which the researchers built on the basis of the above data – could provide an answer: the power of the bird’s brain (the so-called brain loads) by this delay in exposure turned out to be only half of what would cause brain damage in monkeys and humans. Apparently, the woodpecker’s brain is simply good at hammering on a tree.

woodpecker
Camera images of a beating black woodpecker (© Sam van Wassenbergh / University of Antwerp)

Chops effectively

“Finally, it has now been shown that there is no shock absorption in beating woodpeckers,” says biologist and bird skull expert Sander Gussekloo (Wageningen UR). “The results are actually quite logical. It is harder to strike a nail in wood with a soft rubber hammer than with a hard iron hammer. And because woodpeckers depend on felling trees, it is likely that they are adapted to cut as efficiently as possible rather than shock absorption. ”

A bigger head and stronger neck muscles would make hammering even better, but it also means more power to the brain. And it can lead to brain damage, the authors write further in the publication. In fact, the head and beak have evolved quite right.

New materials

“It may be that some adjustments will be made to the conclusions in the future because the researchers’ opportunities for admission to zoos were limited,” Gussekloo continues. “In addition, the authors use the limit values ​​for concussion for humans and great apes, while the limit values ​​for birds may be elsewhere. Although there is a good chance that these values ​​are higher for woodpeckers because there is less room for brain movements in the skull. In addition, woodpeckers may have a brain damage repair system. “

According to Gussekloo, the results may also be of interest to materials researchers. “The woodpecker’s skull is very strong, light and also agile. Further analyzes may therefore lead to the development of new materials or structures. “

Sources: Current Biology, University of Antwerp via EurekAlert!

Photo: © Sam van Wassenbergh / University of Antwerp

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