Cranial kinesis facilitates quick retraction of stuck woodpecker beaks.

Much like nails that are hammered into wood, the beaks of woodpeckers regularly get stuck upon impact. A kinematic video analysis of pecking by black woodpeckers shows how they manage to quickly withdraw their beaks, revealing a two-phase pattern: first a few degrees of beak-tip-down rotation about the nasofrontal hinge causes the tip of the upper beak to be retruded while its proximal end is lifted. Next, the head is lifted, causing beak-tip-up rotation about the nasofrontal hinge while the lower beak starts retruding and initiates the final freeing.