Hi - I've got 5 pullets who are about 17 weeks old. They were obviously raised inside as they had to be encouraged to go out of the coop into the chicken run on their first day - once outside they appeared to be very happy, however we have to physically put them back in the coop at night - when will they eventually get the message? Any tips appreciated. Also we don't have food in the coop at night - only water - is that ok?