Thanks for the suggestions. I wish I could simply blast them out of the sky (they are protected, and I'm also in a residential area). I have partially tackled the bee problem by having the house sprayed, but unfortunately it's not 100%.

I like the idea of a motion activated sprinkler system. Also the suggestion to string up some clear fishing line might help as they only peck at the wood they can reach when sitting on the edge of the roof.