I rode my bike to work this morning and heard the oddest sound. Several blocks later I found a hairy woodpecker showing off for the girls. He would drum a little then stop to look around and see if anyone noticed. I am sure that he wasn't just hungry as he was drumming, not on a tree but on the aluminum flashing that capped a telephone pole. He had chosen a spot where the metal pulled away from the wood to form a hollow drum. No wonder the sound carried so far.
Clever little birdbrain.