Pounding a tree with your head 12,000 times a day would tend to give one a headache, but for woodpeckers, it’s all in a day’s work. How do they manage? Corey Binns on Live Science interviewed Ivan Schwab (UC Davis) who explained some of the specialized adaptations in a woodpecker head: thick muscles, spring-like bones, a third eyelid, a compressible bone in the skull, a firm outer eyeball, and a rigid brain without cerebrospinal fluid. “Along with their straight-as-an-arrow strikes at the tree, which safeguards against head trauma, birds” bodies are designed to absorb the impact,” he said. The whole bird participates in the act. The third eyelid, for instance, closes a millisecond before impact, preventing the eyeball from popping out as the woodpecker hammers its beak into the wood up to 20 times a second. Specialized claws hold the bird in the vertical position, and tail feathers brace it against the trunk. Schwab explained that without these adaptations woodpeckers would not advance. The excuse, “Not tonight, honey, I’ve got a headache” would quickly bring an end to the woodpecker heritage. Either they are very tolerant of headaches or the systems work as “designed.”
It was nice of Corey and Ivan to spare us evolutionary tales in this short but fun look at a natural wonder. For a more complete look at the wonders of woodpecker anatomy, learn from Job Martin in the delightful films Incredible Creatures that Defy Evolution.