I can picture your mockingbird barking, lol. We had one that would sing for us every night at 5 pm sharp. He would go through all of the other birds' songs, singing faster and faster with each round. One night he perfectly mimicked the sound of the siren of a passing firetruck.
I wonder if birds start to build their nests in unsafe places when they are around humans a lot. Our robins nest too low to the ground and on exposed branches, and I think it may be that they have a false sense of security with us being in the backyard so much.
We have large holly balls next to our patio and we have to stop birds from nesting in them every spring, otherwise we will have angry momma birds attacking us. You could try doing the same. Once you see them start building, start pulling the nest out. They will take the hint and move elsewhere.