|Red-Bellied Woodpecker- MDC|
Our brains are suspended in fluid within the skull. If we were to hammer our head against a tree, the sudden stop of the head cause the brain's forward momentum to bang it against the inside of the skull. This is the mechanism of football player's concussions.
Woodpeckers avoid this because their brains fit tightly inside the skull with no room to slosh around. Their brains are small without a lot of mass to build up momentum and their skull is made of somewhat spongy bone which helps cushion the blow. Finally, they tense their mandible muscles just as they strike, letting the body absorb much of the shock.
Another adaptation which is fascinating is their tongue. Hiltonpond.org has pictures showing the barbs at the end of the tongue and a red-bellied woodpecker's fully extended tongue which is three times as long as its beak. If we had the same tongue to head ratio, our tongue would be 2 feet long! The barbs allow them to extract beetle larvae and other prey from deep inside the tree. You could say that woodpeckers speak with forked tongue, a positive attribute in the bird world.