Our 6 chicks are only 7 weeks old. We use a long bamboo pole to herd them back to the coop. I remembered seeing a picture once of a child herding geese with a long pole. I didn't know if it would work with chickens, but it does. For some strange reason they will not go past the bamboo pole, so we just have to switch it from side to side to steer them in the direction we want them to go. It helps to do it slowly. If you get moving too quickly it spooks them and they try to make a break for it. A couple of times they have gone back to the coop on their own, so maybe eventually, they will do that all the time.