Woodpeckers have special foam linings in their skulls that cushion their brains, right?
WRONG. This onetime ornithological hypothesis has become so popular that it’s now a birding myth, repeated online so often that people accept it as proven science.
The truth—as I discovered in a fascinating video from the Cornell Lab Birding Academy — is at once much simpler and more difficult to explain. The researcher who leads us through this video is an MIT Materials Scientist. She specializes in protective foam and says there is no evidence of cushioning foam in the woodpecker skull.
She then walks you through a rapid sequence of physics and math, leading you to the deceptively simple answer.
It all starts with a beautiful Acorn Woodpecker, injured and unable to fly, who was rescued by a park ranger. Over time, the ranger found the Woodpecker would respond to the clicking of his keyboard by pecking on a board.
This provided the ideal setting for a team of Stanford neurologists to help solve this puzzle. They found the bird was banging away at velocities averaging 15 mph. The decelerative force that was registered upon impact was -1500x the force of gravity (-1500g) which is enough to knock a human into the next life on first blow. (Human brains can tolerate -100g.)
Fortunately for Woodpeckers, however, they aren’t people:
- For starters the Acorn Woodpecker brain is ⅛ the mass of our human brain, making the bird able to tolerate 8x what we can endure.
- Secondly, Woodpecker brains are positioned in the skull very differently from human brains. The effect of this is to dilute the decelerative force over a relatively greater area, giving the bird’s brain an additional 2x advantage over our own.
- Thirdly, the duration of impact for a Woodpecker’s peck is much shorter than for a typical human incident, such as a car accident or a football tackle. It’s actually about ¼ the duration of a human impact, giving the bird an extra 4x edge.
- Finally, if you multiply all three factors, you’ll find the Acorn Woodpecker has an 8x2x4 advantage, making the bird able to tolerate 64x the human limit, or -6400g.
This provides the ranger’s pal with a very healthy margin to handle his -1500g pecks, with no need for protective foam. Results will naturally vary for each Woodpecker species, but we should expect the same three factors to protect the bird: mass of brain, area of exposure and duration of impact.
For more detail and a highly entertaining presentation, I warmly recommend the MIT Scientist’s demonstration, one of many free videos provided by the Cornell Lab Birding Academy.
NOW, ON TO MY PHOTOGRAPH. Donny here is the male child of a female Downy Woodpecker who became a cherished friend two years ago. I remember when she took him to my suet feeder and left him there to puzzle it out — which he eventually did, after providing me with a very cute photograph of a bewildered adolescent Downy!
Now Donny’s all grown up, and still visits now and then. I love how he positions his red cap to catch the golden hour sunlight — and lingers long enough to to give me a sequence of photographs. It looks to me as if he’s crowned with flames!
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