Our local bird store is trying out a new concept that seems to be catching on. Bluebird houses with a plexy glass sunroof. He drills a nice sized hole in the roof allowing sunlight in and covers it with plexy glass. The sparrows do not like the sunlight protruding in where it does not seem to bother the blues. He’s running a test cycle this year in several parks around the area. So far so good. Thought I would share.