Woodpeckers are unique birds well known for their high-impact lifestyles. When these small birds smash their beaks against trees, they subject themselves to forces to would typically knock a person unconscious.
Ornithologists have long assumed that the shape and composition of the bird's skulls have evolved to dampen the shock. However, a recent analysis suggests that the birds do not have, nor do they need, this kind of protection.
Why Don't Woodpeckers Need Shock Absorbent Skulls?
In a recent study published in the journal Current Biology, titled "Woodpeckers minimize cranial absorption of shocks." researchers filmed three captive woodpecker species pounding away. The team found that the bird's heads behave like stiff hammers to peck efficiently. If the birds had shock-absorbing skulls, the hardware would get in the way.
The authors conclude that because the woodpecker's brain is small, they do not sustain the kind of damage that humans would endure during similar impacts.
Wesley Hochachka, a Cornell Lab of Ornithology ecologist who was not involved in the research, says that it seems that the impacts suffered by the woodpeckers in their high-impact lifestyle are not as severe as people have long assumed.
Woodpeckers drum their beaks onto trees in search of food, build shelters, and communicate during their breeding seasons. Hochachka says that this is basically what the birds do to survive. Hence if the birds aren't sleeping or resting, they are likely pecking on something.
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Understanding Woodpecker Anatomy and Behavior
Sam Van Wassenbergy, a University of Antwerp biomechanist and co-author of the paper, explains that when woodpeckers strike their beaks into tree bark, their head abruptly decelerates. With this kind of impact, brain tissue at the front of the skull tends to compress while tissue at the back is pulled from the braincase, reported PopSci.
He adds that it's logical to expect that the birds have adapted to not getting headaches or concussions during their daily activities.
Many believe that woodpeckers have developed cushioning in their skulls to serve like helmets or airbags. Some proposed that the spongy bone between the bird's braincase and beak could minimize the shock from the impact.
To understand the mystery, researchers captured more than 100 high-speed videos of six birds from three species pecking as fast as roughly 16 feet per second. The birds covered a range of geographies and body sizes. The team then tracked the movements of several points on the bird's beak, eye, and skull to understand how their braincase moves.
Van Wassenbergh explains that for humans, we know roughly when a concussion can be expected, with the team using this as a reference to compare the pressure loaded onto the birds—adding that the woodpeckers needed to hit the wood twice as fast and stiffer than usual to encounter any injury.
John Bates, a curator of birds at the Field Museum of Natural History, Chicago, says that the data looks convincing but still does not rule out the possibility that the woodpecker's routine pecking could give rise to brain damage over time.
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