I have four 16 week old cochins, two red sex-links, and four 10 week old silkies. At night, they go into the coop and huddle in the corner. I have only found them on the roost by themselves two times and that was when the cochins and reds were about 10 weeks old. I have put them all on the roost each night and they immediately fly down. When will their instincts kick in and/or how can I train them?