Why woodpeckers don't need helmets but footballers do

If a human hammered away with his head the way this male red-bellied woodpecker does, his brain would soon turn to mush.

According to Random Animal Facts, woodpeckers have a:

[R]elatively thick skull with relatively spongy bone to cushion the brain; there is very little cerebrospinal fluid in its small subarachnoid space; the bird contracts mandibular muscles just before impact, thus transmitting the impact past the brain and allowing its whole body to help absorb the shock; and its relatively small brain is less prone to concussion than other animals.

Incidentally, there are occasional glimpses of the red feathers on the belly, which is why it gets its name. That's not quite as much as a "duh" as you might think because it's rare to see the belly feathers.