When you hammer a nail into a tree or a block of wood, it stays there. That's how nails are useful to us. Now consider the woodpecker. A woodpecker drives its beak into a tree with the force of a hammer, but then immediately pulls the beak out to hammer again. You've probably never thought about that before, but scientists have, and by slowing downside close-up footage of a woodpecker in action, they've figured out how they do it.
Once the tip of the woodpecker’s bill hits the wood, the bird’s head rotates to the side ever so slightly, lifting the top part of the beak and twisting it a bit in the other direction, the videos reveal. This pull opens the bill a tiny amount and creates free space between the beak tip and the wood at the bottom of the punctured hole, so the bird can then easily retract its beak.
-via Boing Boing