If you hit your head against a tree trunk all day long, you probably wouldn't feel too great and neither would your brain!
But, woodpeckers hammer their heads into trees with a force of 15 mph, 20 times a second. So why don't they have a constant headache?
Unlike the human brain, the woodpecker's brain is tightly confined by muscles in the skull and a compressible bone. This keeps the woodpecker brain from jiggling around when the bird is stabbing away at a tree trunk.
Along with their straight-as-an-arrow strikes at the tree, which safeguards against head trauma, birds' bodies are designed to absorb the impact.
One millisecond before a strike comes across the bill, dense muscles in the neck contract, and the bird closes its thick inner eyelid.
Some of the force radiates down the neck muscles and protects the skull from a full blow. A compressible bone in the skull offers cushion too.
Meanwhile, the bird's closed eyelid shields the eye from any pieces of wood bouncing off the tree and holds the eyeball in place.
Ivan Schwab, an ophthalmologist (someone who examines and treats diseases and injuries in and around the eye) from the University of California said: “The eyelid acts like a seat belt and keeps the eye from literally popping out of the head, otherwise, acceleration would tear the retina!”
So overall, we now know that a woodpecker’s skull is just like an internal bike helmet to keep its brain from getting hurt.
Some scientists even think that some of the things they found out about woodpeckers can be used to make better bike helmets!