Woodpeckers also have, well, a head for pecking.
For one, woodpeckers have tiny brains—just 0.07 ounce. The bigger the brain, the higher the mass, and thus the higher the risk of brain injury, says Lorna Gibson, a professor of materials science and engineering at MIT who has studied woodpecker brains.
“Size is the most important thing,” says Gibson, an avid birdwatcher who documented her results in a video series.
Another factor that protects woodpecker noggins is the limited time the tree and their bill are in contact, she says. It’s brief—just one-half to one millisecond. By comparison, a typical human head injury happens between about 3 and 15 milliseconds.
The outside of woodpecker skulls made of dense bone, while the inside is porous bone, Gibson says.
The force applied during pecking are “distributed around the skull to the sturdy bone at the base and the back,” keeping the pressure off the brain, says Richard Prum, evolutionary ornithologist at Yale University via email. (Related: “Woodpeckers are Pros at Protecting Their Brains.”)
Woodpecker brains also fit snugly in those skulls, preventing the organ from banging around. The orientation of the brain is also important, MIT’s Gibson says: It sits at an angle toward the back of its head, like a half orange with the flat side facing the front. That creates more surface area to absorb those exacting blows.
A 2011 study suggested that the hyoid apparatus, a bone-and-muscle structure that wraps around the woodpecker skulls, also keeps the brain safe.
“The bottom line,” Prum says, “is good evolutionary design.”