I have 6 2-3 month old girls and I have just recently started letting them out in the yard. They stay pretty close to the coop but they NEVER GO BACK IN ON THEIR OWN! My neighbor has maybe 25 full grown hens and she literally yells "go home girls" and they all go home, meanwhile I'm catching each one to put them back inside. I heard they would start to go in once it began getting dark but so far that's not the case. Any suggestions?