When we started raising chickens, we had four of them that would always run out of the yard and on the street. We tried everything to keep them in, including fishing wire over the fence, a bamboo privacy to cover our other fence (the dogs would scratch it up though, leaving big holes.) One day, as we were driving up the road, we saw four little things scratching around in the middle of the road. When we got closer, we saw that it was the chickens. We got them in and everyone was fine.
Another time, we were all inside when the neighbor called saying our chickens flew into his garden. He wasn't upset, he actually said they could come over more often.