For the last couple of weeks, the co-homeowner and I have been hearing the sound of a woodpecker pounding holes in the siding near our bedroom window. When we yell at him (and it is a him according to our bird book) he leaves, but he's managed to create 2 significant holes, the largest of which is about 2 inches wide and 1 1/2 inches deep. A little research showed that woodpeckers can be deterred by shiny objects, especially if they're blowing in the wind. I decided to make a zero cost bird deterrent out of an unused aluminum roasting pan, some twine, and short nails. Hope it works!