Excellent! Maybe they'll chase away your robin attacking the windows.
Or perhaps ... ever watch Hitchcock's "The Birds"?
Speaking from experience, the robin attacking the window isn't bothered in the slightest by the woodpecker attacking the aluminum. About the only thing I didn't try to deter the robin was a cat, because I'm allergic to them.
The woodpecker, I thought that meant that they could hear insects inside. Which is quite possible under our aluminum fascia. But on a chimney cap?