Why don’t woodpeckers get a headache?
It’s a triumph of adaptation involving muscles, bones, physics and brains. Firstly, they’re a sure shot – the angle of impact is all important, and woodpeckers always deliver a blow ‘straight on’, greatly reducing the stress caused. Woodpecker’s bills (beaks) are ‘reinforced’ and particularly strongly built, with a thick, horn-like covering, and a specially adapted hinge to the skull, further reducing the effects of impact. Their skulls consist of a spongy yet extremely strong bone, which helps cushion and protect their brains from the effect of the blows.
Woodpeckers’ brains are also specially adapted – where we would suffer trauma as our brain ‘rattles around’ in cerebral spinal fluid, a woodpecker’s has virtually none, and with the brain being so small (proportionately as well as actually), the force of each impact is spread over a much greater area. To aid this further,specialised muscles in the bird’s neck are like highly evolved shock absorbers, distributing the effects of impact throughout the entire body. And then there are the specially adapted eyelids and nostrils…
Mark Pearson, Cockney Sparrow Project Officer, London Wildlife Trust