Wednesday, 11 November 2009

On the merits or otherwise of head banging

After a head-bangingly frustrating couple of weeks without the means to recharge my camera battery I am at last back in business. The charger had not in fact disappeared off the planet. Rather, it was in the first place I looked, if only I had seen it.  Its reappearance coincided with that of a great spotted woodpecker in the back garden.  I watched it hop up the poplar tree banging away at the bark, chips flying in all directions. You can see the individual chisel marks on the left hand side of the gash as it worked away looking for edibles.

It reminded me of a gannet.  Yes, I know that gannets don't climb trees but the link is to do with how both birds protect their brain against the force of an impact - the gannet as it hits the water and the woodie as it thumps the tree.  I pontificated on the gannet a couple of posts ago but what about the woodpecker?

Some research done with high speed cameras showed that the pecker's beak hitting the wood generates forces one thousand times that of gravity. If that was you you'd be in trouble. Apparently, the bird survives because it has a small smooth brain, tightly fitted into a skull cavity with very little fluid filled space around it, unlike us, and a more spongey bone structure.  Also key apparently is that it always pecks in a straight line thus avoiding twisting or rotational forces that brains don't like.

The piece I read about the high speed camera research explained that the bird closes its eyes a millisecond before each and every hit (up to 20 times a second), going on to ponder whether that's to keep the wood chips out or the eyeballs in!  Nice one.

1 comment:

  1. Amazing thought, that, closing their eyes 20 times per second - their vision must floicker like those old hand-cranked movies!