I have three crested polishes that love to roost at the opening to the coop at night. There is a tiny lip to the door that they think is a perfect perch. There is enough space for two at a time, so the third rests on top of the racks I built inside the coop with the other chickens. I want for them all to get up there, however. Is there something I can do to easily dissuade them from perching there?