We had a pair of adults that spent a few days taking turns at seemingly trying to enlarge a bird house opening that had a metal opening guard. One would peck for about 15' and then they would switch off and the other one would work on it. They were relentless, and seemed to be pecking at the wood behind the edges of the guard.
I thought about taking the guard off, but was hoping they would move to a box with a larger opening on the other side of our yard. No such luck. After a few days, they gave up. I would have loved it if they nested in our yard!
