One of my former neighbors were raising chickens in their backyard. The chickens would get out of the yard almost daily and there would be a hen parade wandering down the street. Eventually someone would chase them back into their own yard. It was comical the first few times it happened, but after a while it became a bit annoying to have avoid hitting a chicken with your car on the way to work in the morning.
Maybe if they had a coop like the one below those chickens would have had less of a reason to leave their yard.