Last year I put up a new bluebird house. I saw a BB comming and going early on, but then nothing. I didn't realize that the wasps had taken it over until fall when I went to clean it out. This year a cute little chickadee has laid claim to it. I always put the dogs' hair out in spring so the birds can use it for lining their nests. This morning I had fun watching chickadee going back and forth between the hair (I put it in an old sunflower seed feeder) and the house...it's amazing how much hair it could cram in it's beak