Any suggestions on how to keep sparrows and other small flying birds out of my chicken coop? They fly in through the little chicken door and fly all around, hitting the walls and upsetting my chickens. I do feed in the coop because when I was feeding outside in the run, the food would get wet and sour. Horrible smell. I am having to go out several times a day and open the bigger door that I walk through so they can fly out. Any suggestions appreciated!