About fifteen years ago, the local electrical company hired a crew of subcontractors to cut and trim any trees that were deemed a threat to powerlines. The crew gave the sugar maple in our front garden a lop-sided haircut, slicing away all the branches on the south side. Regrettably, the equipment they used must have carried spores from a diseased tree: fungus swarmed over the cut branches, then killed the whole maple.
The dead tree stood next to the house, so its upper trunks had to be cut down. We left the lower ten feet standing, though. This part, even if it fell, presented no danger to the house. Ever since, the stump has gradually rotted away, occasionally calving chunks of bark, but mostly turning slowly, slowly to punk and duff.
The birds love to perch atop the tall stump, as have two generations of housecats. Woodpeckers also include the rotting maple on their rounds and this week a pileated woodpecker made a stop. I poked a microphone out of the cat-flap and recorded the bird’s hammering and the powerful sound of its thirty inch wingspan as it took flight.
As you listen, imagine the slamming impact of beak on wood. Human brains are concussed by forces ten times weaker than those that pileated woodpeckers experience. They’d make a fine mascot for a football team. The woodpeckers’ heads attain speeds of 6-7 meters per second before impact, they then hit the trunk and decelerate at 13,000 meters/second^2 or 1000 g (see Wikipedia for interesting comparative examples of “g”). The birds tolerate this pounding because their multi-million dollar contracts specify that they must. And because they are protected by the angle of beak to brain, the shock-absorbing design of the skull, the tightness of the brain in its case, and the elasticity of muscles.
The spectrogram gives a visualization of the sound, with time moving left to right, and frequency (pitch) shown on the vertical:
These two clips show short segments, one from the beginning and one from the end of the recording: