HEADBANGER!

Woodpeckers smash their beaks against hard trees more than 10,000 times a day. If a person did this even once, it could cause an injury to their brain. So why don’t woodpeckers’ brains turn to mush? 

For years, scientists assumed woodpeckers had cushioning in their skulls. It would absorb and lessen the force of each impact. This idea was repeated in articles, textbooks, and information at zoos. 

Even though this idea was communicated as a fact, “there haven’t been any real tests to prove it,” says Sam Van Wassenbergh. He’s a biologist at the University of Antwerp in Belgium. He studies biomechanics­, or how animals move their bodies.

The shock-absorber theory doesn’t make sense, says Van Wassenbergh. A woodpecker drills into wood to find insects. As its head speeds forward, the movement produces energy. A cushioned skull would absorb some of the energy. That would decrease the force of the peck. 

Woodpeckers survive by pecking. So why would they evolve to peck less effectively? Van Wassenbergh decided to see what was really happening.

First, the researchers took videos of woodpeckers’ heads in motion. Each peck lasts less than a second. The scientists used high-speed cameras to record this rapid movement. The team studied the videos of the birds. 

The scientists made an informed guess called a hypothesis: If the birds’ skulls had shock absorbers, the skull and beak would appear to squish in the videos. They would act like a spring compressing. But that’s not what the researchers saw. The birds’ heads and beaks didn’t squish together.  

Then the team created a computer model of skulls with and without shock absorbers. They found that the force created by a skull with a shock absorber was much less powerful than one without it. 

The team concluded that woodpeckers’ skulls don’t absorb shock. So why doesn’t constant pecking damage the birds’ brains? 

The scientists believe that pecking isn’t dangerous because the birds’ brains are so small. “Small masses can tolerate stronger impact forces without being damaged,” says Maja Mielke, a biologist who worked on the study. “A housefly can hit a window over and over again without injuries, while a human would suffer quite a bit if they ran into a window.” 

The team helped bust a well-known woodpecker myth. “This experiment just shows that it is still worth having a closer look at things we think we already understand,” says Mielke.