From recent experience, I can confidently answer: A LOT.

We live in a fairly wooded area. Every morning for the past 6 weeks, we are startled awake by a beak jackhammering into a bit of tree trunk. It has a rhythm and resonance than can only be described as irritating. Being the appreciative sort, Miles and I throw our pillows atop our heads and wish it away.

You have to wonder where the joy in wood-pecking is derived, don't you? Or maybe the bird kingdom doesn't have the aversion to launching their heads toward solid material as does mankind. Or most of mankind...can't forget the inebriated!

I just read this: "Some species drum on trees to communicate to other woodpeckers and as a part of their courtship behavior." I imagine a swinging bachelor armed (winged) with a slew of really terrible jokes. Brings all new meaning to the cheesy reminder to laugh, knock on wood, I'd say. Do they ever bark up the wrong tree? That probably goes without saying....it's the hard-knock life.