Whenever I let my chickens free-range, I leave the door of my tractor coop open so that they can go in to eat, drink, lay an egg, etc. whenever they like. However, my neighborhood birds have recently gained enough courage to go in my tractor coop to eat the chickens' food whenever the door is open. I don't mind if they eat some food, but am concerned that my chickens could catch some disease from these wild birds. I'm not sure what kind they are - small, brown, possibly sparrows(?) I could close the coop door and leave water outside for my chickens, but would much rather let them go in and out as they please. Thoughts, anyone?